Imagine how overly advanced his engine is with the low end of the advance curve starting at the full advance point... doubly advanced. Just another bad video by the YouTube Certified Techs
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Rebuild of my English CB175K6, 1972
- Thread starter 911hillclimber
- Start date
Imagine how overly advanced his engine is with the low end of the advance curve starting at the full advance point... doubly advanced. Just another bad video by the YouTube Certified Techs
Richard Pitman
Veteran Member
Just illustrates the point that there is so much ill informed rubbish on YouTube …
Those unmarked lines are used with a strobe light, to dynamically check timing at full advance.
Those unmarked lines are used with a strobe light, to dynamically check timing at full advance.
Yes, and in the first 20 comments below the video there are at least 5 people telling him he did it wrong despite having the manual in front of him. And someone asked what qualifies the bike to be a race bike... LOL
In fairness, that index to mark alignment would be correct on a race bike that had the units fly-weights pinned or welded fully open (advanced), which also meant the lowest sustainable engine speed would be about 2800/3K......NOT street-able at all......
True, if only the video poster actually knew what constituted a race bike... stock scrambler exhaust is the first clue that he had no clue. Doubt the guy was smart enough to know how to lock the advancer at full advance, or even that it could be done
mike in idaho
Veteran Member
Like they say: "a little knowledge is a dangerous thing".
911hillclimber
Veteran Member
: "a little knowledge is a dangerous thing".
That will be me then!! LOL
Never seen those marks referred to before, and I think he got the bike in that condition and says it runs so well, so left it.
Will chase the re-bore next Tuesday (machinist works 3 days a week, long weekends) as I'm itching to press-on and have another pop at getting the thing to work.
With the fresh bores, new Honda rings and pistons, oil seals on all 4 valves the motor should be sweet as can be, so if this effort is less than perfect, it will be new carbs, those ebay Chinese copies they apparently have sold 280 sets of.
For a 4 stroke to work (well) it needs ignition (tick), fuel (maybe) and compression (doubt it until the rebore)
I think the compression was 110 psi warm (not hot) and I'm expecting far better this time.
Might even find 1200 rpm!
That will be me then!! LOL
Never seen those marks referred to before, and I think he got the bike in that condition and says it runs so well, so left it.
Will chase the re-bore next Tuesday (machinist works 3 days a week, long weekends) as I'm itching to press-on and have another pop at getting the thing to work.
With the fresh bores, new Honda rings and pistons, oil seals on all 4 valves the motor should be sweet as can be, so if this effort is less than perfect, it will be new carbs, those ebay Chinese copies they apparently have sold 280 sets of.
For a 4 stroke to work (well) it needs ignition (tick), fuel (maybe) and compression (doubt it until the rebore)
I think the compression was 110 psi warm (not hot) and I'm expecting far better this time.
Might even find 1200 rpm!
911hillclimber
Veteran Member
Cylinder block back today from Readspeed and the bores look perfect.
Despite starting from standard size to +0.75mm over, the one barrel only just cleaned=up (of top ring located corrosion) with the hone, so a close call.
This was not the sleeve off Richard but the one from the breakers.
Before painting the block, checked the new Honda '0.75 over' rings in the bores.
2 x top rings, gap is 0.008", oil ring is 0.010".
Piston clearance is 0.002" on diameter.
The engine paint takes a few days to cure, so I hope to build the engine up on Sat or Sunday. Progress at last.
Despite starting from standard size to +0.75mm over, the one barrel only just cleaned=up (of top ring located corrosion) with the hone, so a close call.
This was not the sleeve off Richard but the one from the breakers.
Before painting the block, checked the new Honda '0.75 over' rings in the bores.
2 x top rings, gap is 0.008", oil ring is 0.010".
Piston clearance is 0.002" on diameter.
The engine paint takes a few days to cure, so I hope to build the engine up on Sat or Sunday. Progress at last.
Slowly but surely it'll get there
911hillclimber
Veteran Member
Indeed, and today was just like that, slow n easy, but progress.
I felt this was going to go well when the last wrist pin clip popped into place in a few seconds, now, that never happens to me, but did today.
After a bit of an effort because the rings now are tighter in the nice bores the cylinder block slipped down to the case with a bit of pressure, A few revolutions of the crank proved the movement to be really nice, so set the crank to TDC.
With the help of the wife to hold the cam chain tight and upright, the head went on.
And then came off.
The text in the Haynes manual forgets the 2 O rings on top of the block, so with them now in place the head was slipped down and the chain positioned TDC and 'O' on the cam gear @ 12 noon. The link clicked into place satisfyingly.
Released the chain tensioner and rotated the crank a few times, all baby-bum-smooth.
Assembly lube all over the cam lobes and the head on and progressively torqued to 13 lbft. Checked the timing AGAIN, and satisfied with the work.
With the engine still on the stand did the tappets. The small square screw head is a pain to turn and hold with a small adjustable spanner, so in a rare moment of inspiration found a Schuco tin plate toy wind up key has the very same square hole and makes a perfect adjuster/holder/and gives great access for the 8mm a/f spanner to nip the nuts up!
One of my other interests are post war Schuco racing cars and you can buy these keys for £3.
The car in the picture below I was given as a Xmas present 60 years ago, mega played with and a very cherished possession.
Put oil all over the tappets and put the covers on.
While on a roll, dropped the engine back into the frame! The thing just went in, all the mounting bolts slipped in (!) and tightened everything up. Wow, what a morning, even remembered to fit the earth ground cable too!
Hope to finish all the outer bits tomorrow.
I felt this was going to go well when the last wrist pin clip popped into place in a few seconds, now, that never happens to me, but did today.
After a bit of an effort because the rings now are tighter in the nice bores the cylinder block slipped down to the case with a bit of pressure, A few revolutions of the crank proved the movement to be really nice, so set the crank to TDC.
With the help of the wife to hold the cam chain tight and upright, the head went on.
And then came off.
The text in the Haynes manual forgets the 2 O rings on top of the block, so with them now in place the head was slipped down and the chain positioned TDC and 'O' on the cam gear @ 12 noon. The link clicked into place satisfyingly.
Released the chain tensioner and rotated the crank a few times, all baby-bum-smooth.
Assembly lube all over the cam lobes and the head on and progressively torqued to 13 lbft. Checked the timing AGAIN, and satisfied with the work.
With the engine still on the stand did the tappets. The small square screw head is a pain to turn and hold with a small adjustable spanner, so in a rare moment of inspiration found a Schuco tin plate toy wind up key has the very same square hole and makes a perfect adjuster/holder/and gives great access for the 8mm a/f spanner to nip the nuts up!
One of my other interests are post war Schuco racing cars and you can buy these keys for £3.
The car in the picture below I was given as a Xmas present 60 years ago, mega played with and a very cherished possession.
Put oil all over the tappets and put the covers on.
While on a roll, dropped the engine back into the frame! The thing just went in, all the mounting bolts slipped in (!) and tightened everything up. Wow, what a morning, even remembered to fit the earth ground cable too!
Hope to finish all the outer bits tomorrow.
Middletons
Veteran Member
One of the many reasons a lot of us around here do not use Haynes and Chilton manuals. Gotta use the factory manual. That said, sounds like you made great progress!
911hillclimber
Veteran Member
It also states the engine mounting bolts to be torqued to 3 to 4 lbft, should be 34 lbft I think..
Richard Pitman
Veteran Member
Roll cage in the Porsche ?
911hillclimber
Veteran Member
Yes, it is my old hillclimb car, owned it for 32 years now, and retired like me! It still has a lot of racing bits on it, I like to remember what it was like when I occasionally use it.
Have a 'real' racing car to scare myself in now....a Lola T492 with a 3.2 litre Porsche flat 6 in it.
Had another good 4 hours on the bike today.
Got the timing to 0.5mm either side of the generator pointer on the F mark, never got it that close before, and was more luck than judgement tbh.
The LHS of the engine is now all buttoned-up and the exhausts on, wires back in, just need to decide which carbs to put back on.
Battery will need a charge and then the 'fun' can begin again.
Will I get sub 1200 rpm? Will they balance, will they smoke, will both pipes have the same heat??
Have a 'real' racing car to scare myself in now....a Lola T492 with a 3.2 litre Porsche flat 6 in it.
Had another good 4 hours on the bike today.
Got the timing to 0.5mm either side of the generator pointer on the F mark, never got it that close before, and was more luck than judgement tbh.
The LHS of the engine is now all buttoned-up and the exhausts on, wires back in, just need to decide which carbs to put back on.
Battery will need a charge and then the 'fun' can begin again.
Will I get sub 1200 rpm? Will they balance, will they smoke, will both pipes have the same heat??
911hillclimber
Veteran Member
Day started well, or rather didn't in the end.
Decided to put the stock carbs on and start the engine.
It started well and ran EXACTLY as it did before all this engine work.
Engine itself sounds nicer, more 'tight' a sound, so pleased with that.
The RHS runs very hot and smoking, LHS quite the opposite, cool and smoke free.
With the carb slide screws fully in, max revs were 2000!
Somewhat disappointed, swopped the carbs to the Chinese units.
Exactly the same. RHS hot etc etc etc
Thus, standing back from this I feel I need to replace again the ignition system which is simply the coil, so ordered another for £14. The used ones I have have all be cut at the HT cable ends and are too short to reach the plugs (which are new).
The RHS is firing well (it's hot) and the LHS must be firing about 15% of the time.
The LHS plug looks new, the RHS looks slightly rich.
Really very tired of this bike now and when/if I get it going I think I will sell it, magic all gone.
Should I feel I fancy a nice classic, I will simply buy a Chinese AJS, £2500 all done and on the road, 100% reliable and great brakes etc and simply works. :frown:
Decided to put the stock carbs on and start the engine.
It started well and ran EXACTLY as it did before all this engine work.
Engine itself sounds nicer, more 'tight' a sound, so pleased with that.
The RHS runs very hot and smoking, LHS quite the opposite, cool and smoke free.
With the carb slide screws fully in, max revs were 2000!
Somewhat disappointed, swopped the carbs to the Chinese units.
Exactly the same. RHS hot etc etc etc
Thus, standing back from this I feel I need to replace again the ignition system which is simply the coil, so ordered another for £14. The used ones I have have all be cut at the HT cable ends and are too short to reach the plugs (which are new).
The RHS is firing well (it's hot) and the LHS must be firing about 15% of the time.
The LHS plug looks new, the RHS looks slightly rich.
Really very tired of this bike now and when/if I get it going I think I will sell it, magic all gone.
Should I feel I fancy a nice classic, I will simply buy a Chinese AJS, £2500 all done and on the road, 100% reliable and great brakes etc and simply works. :frown:
2K max revs might indicate a problem with the advance unit.....Just in case you decide against giving up on it......
Both HT cables must achieve a common connection for either to fire...This might mean spark jumping to ground somewhere before the plug......
Both HT cables must achieve a common connection for either to fire...This might mean spark jumping to ground somewhere before the plug......
911hillclimber
Veteran Member
Thanks for your input.
calmed down a bit now, but certainly a bit fed up with the thing.
Tomorrow, will restart it and swop the leads over to see if the current condition moves across the engine.
It is a new coil, leads caps etc etc so should be out of consideration, but worth combing through it all.
will check continuity across the gin system too.
Why is this so troublesome!
calmed down a bit now, but certainly a bit fed up with the thing.
Tomorrow, will restart it and swop the leads over to see if the current condition moves across the engine.
It is a new coil, leads caps etc etc so should be out of consideration, but worth combing through it all.
will check continuity across the gin system too.
Why is this so troublesome!
Richard Pitman
Veteran Member
Compression same on both sides now ?
Not something random, like a blocked exhaust pipe ?
Not something random, like a blocked exhaust pipe ?
911hillclimber
Veteran Member
Will check the comp tomorrow even though the parts are fresh.
Exhausts are new DS items and at times the heat difference has stopped over for no reason.
Time will tell....
Exhausts are new DS items and at times the heat difference has stopped over for no reason.
Time will tell....
That thing is certainly beating you up...
911hillclimber
Veteran Member
Indeed.
It will be something stupid I've done, or a faulty part.
My 76 cb175 was almost the same grief. Got that going and have no idea what I did but it worked. Richard may remember the chaos.
Me and old bike don't go together well, I love the restoration, but seem to fail at the last corner.
Tomorrow is another day, AND NEVER GIVE UP!
Coil arrives Saturday, but will try a few things tomorrow;
Start as it is, get it hot and note the 'hot' side.
Swap plug leads over, see if the hot side moves with it (= ignition)
If so, try to find out why. The one side of the engine is not cold, it is firing, just not every time as the other side does.
Bit of time on google will give me ways to check the coil.
If the hot side does not move then I presume not the coil but the grounding of the HT lead/plug.
Hard to thick what else.
It will be something stupid I've done, or a faulty part.
My 76 cb175 was almost the same grief. Got that going and have no idea what I did but it worked. Richard may remember the chaos.
Me and old bike don't go together well, I love the restoration, but seem to fail at the last corner.
Tomorrow is another day, AND NEVER GIVE UP!
Coil arrives Saturday, but will try a few things tomorrow;
Start as it is, get it hot and note the 'hot' side.
Swap plug leads over, see if the hot side moves with it (= ignition)
If so, try to find out why. The one side of the engine is not cold, it is firing, just not every time as the other side does.
Bit of time on google will give me ways to check the coil.
If the hot side does not move then I presume not the coil but the grounding of the HT lead/plug.
Hard to thick what else.
911hillclimber
Veteran Member
Yet more hours on this cb this morning with some results though.
any comments would be most helpful.
Swapped the ignition leads over and still the Right side is hot/smokey, left cool/cold, no smoke. right plug sooty, left side clear/new.
Found the coil off my previous gold cb175, and fitted that. The HT leads just about reach.
Got it going (bit reluctant, needs full choke) BUT both cylinders hot, though the left needed more time to 'catch-up' and the right got super hot, the down pipe is straw colour for about 100mm from the head yet the plug is sooty! Left side still looks new or super weak??
Still, both hot is a good move forward.
This afternoon I hope to find time to put the stock carbs back on and see what I have.
The new coil pack is obviously duff, so pleased to have a new one coming (different supplier) and also a new condenser just in case.
any comments would be most helpful.
Swapped the ignition leads over and still the Right side is hot/smokey, left cool/cold, no smoke. right plug sooty, left side clear/new.
Found the coil off my previous gold cb175, and fitted that. The HT leads just about reach.
Got it going (bit reluctant, needs full choke) BUT both cylinders hot, though the left needed more time to 'catch-up' and the right got super hot, the down pipe is straw colour for about 100mm from the head yet the plug is sooty! Left side still looks new or super weak??
Still, both hot is a good move forward.
This afternoon I hope to find time to put the stock carbs back on and see what I have.
The new coil pack is obviously duff, so pleased to have a new one coming (different supplier) and also a new condenser just in case.
As simple as these ignition systems are, it's hard to believe you could randomly buy a new coil and get a bad one. Seems you haven't had the best luck as of late
911hillclimber
Veteran Member
Yes, it has never run on both cylinders right from the start.
I changed it to new simply because I thought it was the best thing to do after the bike had been holed-up from 1986.
Got a permission to go back to the patient this afternoon for the carb switch.
Spanners crossed...
I changed it to new simply because I thought it was the best thing to do after the bike had been holed-up from 1986.
Got a permission to go back to the patient this afternoon for the carb switch.
Spanners crossed...
Richard Pitman
Veteran Member
Just out of interest, I have a pair of those Wincycles carbs on the way, ordered a little while ago now. Probably stuck in Customs or something. Intending to fit them to my SL175 test mule when they arrive, weather permitting. Might be the answer to your problem also ?
Are we SURE that you are getting a good seal between carbs, manifolds, and head?......
Had one that had a bad (hidden crack) insulator block that only ran on one cylinder until warm and above a quarter throttle......
Had one that had a bad (hidden crack) insulator block that only ran on one cylinder until warm and above a quarter throttle......
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911hillclimber
Veteran Member
After this afternoon it will get deeper...beware, this is a long story..
Got it going on the original carbs. Still the same, luke warm left, very hot right.
The left carb 'chugs' as the engine is running, the right carb is sweet. This sound is clear right at the mouth of the carb, the carb sometimes is wet with fuel.
I screwed the left carb's throttle screw right in and eventually the right carb's screw almost right OUT and got 1800 rpm AND heat even on both sides.
The engine just doesn't sound right to me and the throttle response is good but takes several seconds to fall to tick over. Tick over will stall after about 2 mins running.
At this stage the plugs were both sooty but the same.
Thus, the sparks are working (old coil) the fuel is there and so is the compression. I replaced the old coil with the new one I thought was faulty...same, both sides hot. (thus the coil is ok!)
Now it takes a deeper dive.
I read the Haynes book again looking for inspiration. It states to tune each carb separately by removing the spark plug on one side, tune the carb on the other. What I think it meant was to remove the spark plug, and ground it. Thus, no combustion on that side, but both plugs sparking.
So, I tried it.
I grounded the removed plug from the left side and started the engine. Ran well too, tick over down to a 'just' sustainable tick over of 1400 according to the tacho, and tweaked the idle mixture screw to rise the revs to 1600 (it would not rise further) and then eased the tickover back to a 1400 level. Throttle response nice, it even sounded quite good.
The temperature of the silencer at the rear peg position was about 30 deg C, hot shower if you will. Plug less sooty, looking good.
Changed over to the left side, grounded the right plug etc.
Set the carb to 1.24 turns out on the mixture and started the bike.
Except is would not start for many tries and then it barely caught and ran terribly, chuffing and farting like a scrap yard dog.
I decided to pack it in for the day and write this saga for you all to ponder.
Tomorrow I plan to remove the left carb. To replace it with the Chinese knock-off and see if anything changes. If it runs then the carb is at fault. I may well then buy some of the carbs Richard has bought even at £110.
If, however, and I think it will not run, there is a far deeper issue, but a learned (car geek) friend also suggests an air leak as has Sprint, so will look closely at the insulator when I swop the carb over. I have in the past sprayed all the interfaces with the engine running with carb cleaner and the engine note never changed, thus I presume there are no air leaks.
My mind turns to the camshaft or maybe sticky valves on the left side.
On the latter, this morning I did a compression test on a cold engine and got both sides @ 84 psi. If a valve was leaking the compression would be radically different I think.
When i first got the bike I realised the cam was a CD cam, no tacho drive, so I bought a 'cb175' cam off ebay in England and the tacho drive parts from the USA. I still have the CD cam which looks great.
I am pondering if the ebay cam is the problem, but certainly not sure. All the lobes look great when I built the engine up.
The ebay cam times out perfectly but the left side has this chuffing sound in rhyme with the rotation of the engine; in sync with the engine speed.
I can modify the CD cam to take the tacho drive peg, but will have to remove the engine which after all this fiasco is not the worst thing to do, 20 mins and it is on the bench.
Any comment most certainly welcome!!
Got it going on the original carbs. Still the same, luke warm left, very hot right.
The left carb 'chugs' as the engine is running, the right carb is sweet. This sound is clear right at the mouth of the carb, the carb sometimes is wet with fuel.
I screwed the left carb's throttle screw right in and eventually the right carb's screw almost right OUT and got 1800 rpm AND heat even on both sides.
The engine just doesn't sound right to me and the throttle response is good but takes several seconds to fall to tick over. Tick over will stall after about 2 mins running.
At this stage the plugs were both sooty but the same.
Thus, the sparks are working (old coil) the fuel is there and so is the compression. I replaced the old coil with the new one I thought was faulty...same, both sides hot. (thus the coil is ok!)
Now it takes a deeper dive.
I read the Haynes book again looking for inspiration. It states to tune each carb separately by removing the spark plug on one side, tune the carb on the other. What I think it meant was to remove the spark plug, and ground it. Thus, no combustion on that side, but both plugs sparking.
So, I tried it.
I grounded the removed plug from the left side and started the engine. Ran well too, tick over down to a 'just' sustainable tick over of 1400 according to the tacho, and tweaked the idle mixture screw to rise the revs to 1600 (it would not rise further) and then eased the tickover back to a 1400 level. Throttle response nice, it even sounded quite good.
The temperature of the silencer at the rear peg position was about 30 deg C, hot shower if you will. Plug less sooty, looking good.
Changed over to the left side, grounded the right plug etc.
Set the carb to 1.24 turns out on the mixture and started the bike.
Except is would not start for many tries and then it barely caught and ran terribly, chuffing and farting like a scrap yard dog.
I decided to pack it in for the day and write this saga for you all to ponder.
Tomorrow I plan to remove the left carb. To replace it with the Chinese knock-off and see if anything changes. If it runs then the carb is at fault. I may well then buy some of the carbs Richard has bought even at £110.
If, however, and I think it will not run, there is a far deeper issue, but a learned (car geek) friend also suggests an air leak as has Sprint, so will look closely at the insulator when I swop the carb over. I have in the past sprayed all the interfaces with the engine running with carb cleaner and the engine note never changed, thus I presume there are no air leaks.
My mind turns to the camshaft or maybe sticky valves on the left side.
On the latter, this morning I did a compression test on a cold engine and got both sides @ 84 psi. If a valve was leaking the compression would be radically different I think.
When i first got the bike I realised the cam was a CD cam, no tacho drive, so I bought a 'cb175' cam off ebay in England and the tacho drive parts from the USA. I still have the CD cam which looks great.
I am pondering if the ebay cam is the problem, but certainly not sure. All the lobes look great when I built the engine up.
The ebay cam times out perfectly but the left side has this chuffing sound in rhyme with the rotation of the engine; in sync with the engine speed.
I can modify the CD cam to take the tacho drive peg, but will have to remove the engine which after all this fiasco is not the worst thing to do, 20 mins and it is on the bench.
Any comment most certainly welcome!!
Richard Pitman
Veteran Member
Am I right in thinking, that to measure the cam shaft lobes for wear you use these figures (mm) ?
Inlet lobes 21 + 4.06, Exhaust lobe 21 + 3.87 ?
Inlet lobes 21 + 4.06, Exhaust lobe 21 + 3.87 ?
911hillclimber
Veteran Member
Food for thought Richard, but..
Put the chinese carb on the left/problem side and it almost didn't start at all. RHS spark plug sparking, so electrically ok.
Checked spark on the LHS and the sparks were huge in comparison (clue?)
Eventually is very reluctantly fired a bit and sounded terrible, popping and banging like everything was a mile off.
Checked all the timing mechanically and electrically, all of, but LHS inlet tappet tight so slackened it off to 2 thou. Tried again, just as bad, maybe worse, so bit the bullet and pulled the engine out, 20 mins so must be getting good at it..
Engine on the bench and slowly took the head apart and noted that the cam chain link was NOT on the '0' mark but 2 teeth off. Now, I am sure I put the link in with TDC and the 0 at 12 noon.
What can that mean?
1
I have it wrong, that link does not HAVE to be at the 0 mark for the engine to run just as long as the timing is right to the 0 and crank TDC.
2
If the chain slipped then both cylinders would be out of time, and neither would run, if at all?
Pulled the tappets out, all good. Removed the CB cam and compared it to the CD cam that was in this cb head when I bought it. All cam lobes measure the same across the peak of the lobe, 25mm +/- 0.1mm
The lobe positions ate the same and I have never read these cams ate different except for the tacho drive.
I'll check the cams to Richard's diagram tomorrow.
The inlet and the exhaust ports all look the same, Ex is a dry dark grey as you would expect.
Cylinder bores look perfect, both pistons are identical , clean and soot-free.
Will strip the LHS valves out tomorrow to see is something is wrong, BUT, so far cannot find anything wrong, just that cam position doubt.
Put the chinese carb on the left/problem side and it almost didn't start at all. RHS spark plug sparking, so electrically ok.
Checked spark on the LHS and the sparks were huge in comparison (clue?)
Eventually is very reluctantly fired a bit and sounded terrible, popping and banging like everything was a mile off.
Checked all the timing mechanically and electrically, all of, but LHS inlet tappet tight so slackened it off to 2 thou. Tried again, just as bad, maybe worse, so bit the bullet and pulled the engine out, 20 mins so must be getting good at it..
Engine on the bench and slowly took the head apart and noted that the cam chain link was NOT on the '0' mark but 2 teeth off. Now, I am sure I put the link in with TDC and the 0 at 12 noon.
What can that mean?
1
I have it wrong, that link does not HAVE to be at the 0 mark for the engine to run just as long as the timing is right to the 0 and crank TDC.
2
If the chain slipped then both cylinders would be out of time, and neither would run, if at all?
Pulled the tappets out, all good. Removed the CB cam and compared it to the CD cam that was in this cb head when I bought it. All cam lobes measure the same across the peak of the lobe, 25mm +/- 0.1mm
The lobe positions ate the same and I have never read these cams ate different except for the tacho drive.
I'll check the cams to Richard's diagram tomorrow.
The inlet and the exhaust ports all look the same, Ex is a dry dark grey as you would expect.
Cylinder bores look perfect, both pistons are identical , clean and soot-free.
Will strip the LHS valves out tomorrow to see is something is wrong, BUT, so far cannot find anything wrong, just that cam position doubt.
Yes. Richard you are correct in adding the numbers.
Odd number of teeth on crankshaft and even number of chain links means evenly positioned master-link will "Travel" as the engine rotates....Will only return to the "0" position momentarily at multiples of 15 (crank teeth) times number of chain links (82 IIRC) crank rotations since the two numbers are not divisible (into each other as whole numbers) ......
911hillclimber
Veteran Member
Thank you, never knew that or even expected that either!
At least that answers why the link is in a different position.
I will strip the LHS valves out to see if something is amiss, but doubt it is a sticking valve as the movement is complete and with the compression test giving identical results for both sides the chamber must seal at the right time.
I'm hoping something will present itself very soon, the engine looks so good so far.
At least that answers why the link is in a different position.
I will strip the LHS valves out to see if something is amiss, but doubt it is a sticking valve as the movement is complete and with the compression test giving identical results for both sides the chamber must seal at the right time.
I'm hoping something will present itself very soon, the engine looks so good so far.
Let's do one of the easy carb tests..... Remove both carbs.... Either disconnect the choke linkage and swap their positions (left carb to right cylinder, right carb on left cylinder) and see if cold side swaps as well, OR leave both off and start while spraying starting fluid (easy-start/ether) in the air space the carbs USED to occupy (NOT directly into the open ports) and see if both sides heat........
Either way you will have a definitive answer as to IF it is a carb related problem.....
Either way you will have a definitive answer as to IF it is a carb related problem.....
911hillclimber
Veteran Member
Thank you for all your help Sprint, most helpful.
I expect to re assemble the engine this afternoon, maybe back into the frame too.
I have found nothing untoward in the engine as I've taken it apart. I've removed the LHS (cold) valves and all ok.
Thus, i believe the basic engine is fine.
As to carbs:
When I did the side-by-side running and the hot RHS worked well (stock carb) the LHS was awful on the stock carb AND the Chinese knock-off carb which is why I pulled the engine. Those 2 carbs cannot be bad in the same way, but as you say, I do have one good one, the RHS.
Will try this swop over and see when all back in. I also have a can of Easy-Start...
I now have the new coil and condenser today. This will leave me with the carbs as suspects in this crime!
If it narrow down to the one carb, I will clean it and try, but probably buy the same carbs as Richard, but will wait for his 'report' on them. Thier ebay advert states over 280 sets sold.
Thanks again.
Graham.
I expect to re assemble the engine this afternoon, maybe back into the frame too.
I have found nothing untoward in the engine as I've taken it apart. I've removed the LHS (cold) valves and all ok.
Thus, i believe the basic engine is fine.
As to carbs:
When I did the side-by-side running and the hot RHS worked well (stock carb) the LHS was awful on the stock carb AND the Chinese knock-off carb which is why I pulled the engine. Those 2 carbs cannot be bad in the same way, but as you say, I do have one good one, the RHS.
Will try this swop over and see when all back in. I also have a can of Easy-Start...
I now have the new coil and condenser today. This will leave me with the carbs as suspects in this crime!
If it narrow down to the one carb, I will clean it and try, but probably buy the same carbs as Richard, but will wait for his 'report' on them. Thier ebay advert states over 280 sets sold.
Thanks again.
Graham.
911hillclimber
Veteran Member
Gasket set arrived 3 day early, so finished the engine build-up this afternoon.
Wife getting good at holding timing chain tight on wires!
This engine is as solid as I can make it now, I am confident there is nothing wrong in the undressed state, and the engine is back in the frame.
Installed my new coil which has different coloured wires from the coil block to the condenser to the one I took off which was different to the original wire colours from Honda...
No instructions came with the part.
Thus, before 12 volts goes on, is there any particular order for the two wires that go to power and the condenser etc? I cannot see a bias in the Haynes manual diagram, but I need to be sure.
Hope someone can help.
Will I damage the new coil if I have them the wrong way round??
Wife getting good at holding timing chain tight on wires!
This engine is as solid as I can make it now, I am confident there is nothing wrong in the undressed state, and the engine is back in the frame.
Installed my new coil which has different coloured wires from the coil block to the condenser to the one I took off which was different to the original wire colours from Honda...
No instructions came with the part.
Thus, before 12 volts goes on, is there any particular order for the two wires that go to power and the condenser etc? I cannot see a bias in the Haynes manual diagram, but I need to be sure.
Hope someone can help.
Will I damage the new coil if I have them the wrong way round??
Doesn't matter on the 175's as the coil is actually an isolation transformer...... Black (or Black/white) wire becomes coil positive......Points and condenser to coil negative Swapping the primary wires only determines in which direction the induced secondary current flows...... Effect is identical.....
911hillclimber
Veteran Member
Good to read, thank you very much for this and your continued help.
I really do not want to go through too many more hoops on this bike.
Wedding anniversary tomorrow, so no garage time I think, but hope to try the carb swop routine soon and get this thing cracked.
I really do not want to go through too many more hoops on this bike.
Wedding anniversary tomorrow, so no garage time I think, but hope to try the carb swop routine soon and get this thing cracked.
Haven't had much to contribute to this one but I'm wondering if your coil is seeing ground. Looking at images it appears the coil should be. The stand off sleeves for the mounting bolts should make ground to the frame and since you've painted the frame they may not.
Coil core does not require grounding in this instance......Spark-plugs don't even need to be grounded to the bike (or engine) they just require a common connection between them (which in this case, the "grounding" to the engine provides).......They will spark just as well with the plugs floating in mid-air IF you jumper across the bent electrodes to complete the "common" connection..... The points and condenser do however require a battery ground...(which is why Honda mounted the condenser on an engine stud)
911hillclimber
Veteran Member
I think all those parts are ground, ie the buzzer in my DVM sings when 'belled' through, but will check again.
I admit to NOT having the mounting tab of the condenser under a cylinder hear stud, but it is under the head cover/bracket/frame top mount plates, but will check the ground with the dvm tomorrow.
The reason for this is the stud with the condenser never seemed to torque up well on my gold cb a few years ago, all a bit 'soft' where the others clicked off solidly.
The circuit diagram does not show the coil to ground, but does for the for the breaker and condenser..
I have always had a good spark on each plug throughout this saga, so have presumed they are all down to ground.
I admit to NOT having the mounting tab of the condenser under a cylinder hear stud, but it is under the head cover/bracket/frame top mount plates, but will check the ground with the dvm tomorrow.
The reason for this is the stud with the condenser never seemed to torque up well on my gold cb a few years ago, all a bit 'soft' where the others clicked off solidly.
The circuit diagram does not show the coil to ground, but does for the for the breaker and condenser..
I have always had a good spark on each plug throughout this saga, so have presumed they are all down to ground.
911hillclimber
Veteran Member
I can say I am utterly exasperated by this pile of cr..
Got it all back together today and it will not start at all.
A recap:
Before all the engine disassembly, it ran on the RHS with the original carb, but not on the LHS.
So, today, put the RHS carb on the LHS of the engine, no carb on the RHS.
Nothing. Just the poor starter motor churning around.
Checked the points gap, checked the timing, checked the valve clearances, checked fuel is in the carb from dry.
Checked all wires in the ignition system for ground or 12v, all ok.
Checked the spark is there on both sides, there but rather weak, nothing like a car spark.
New coil, new condenser. If the coil is a 6V would that give a weak spark?
Questions:
Can anything in the bike's loom kill the ignition even though I have a spark (weak) and the neutral light is green and bright?
Is there ANYTHING I am missing?
Tomorrows plan is to put the RHS carb back to the RHS and see if that works as it did before. If not, then something has changed during the re-installation.
There is a 4 wire plug/socket from the loom to the generator, can those wires cause such grief?
As ever, any help appreciated.
Got it all back together today and it will not start at all.
A recap:
Before all the engine disassembly, it ran on the RHS with the original carb, but not on the LHS.
So, today, put the RHS carb on the LHS of the engine, no carb on the RHS.
Nothing. Just the poor starter motor churning around.
Checked the points gap, checked the timing, checked the valve clearances, checked fuel is in the carb from dry.
Checked all wires in the ignition system for ground or 12v, all ok.
Checked the spark is there on both sides, there but rather weak, nothing like a car spark.
New coil, new condenser. If the coil is a 6V would that give a weak spark?
Questions:
Can anything in the bike's loom kill the ignition even though I have a spark (weak) and the neutral light is green and bright?
Is there ANYTHING I am missing?
Tomorrows plan is to put the RHS carb back to the RHS and see if that works as it did before. If not, then something has changed during the re-installation.
There is a 4 wire plug/socket from the loom to the generator, can those wires cause such grief?
As ever, any help appreciated.
Jays100
Veteran Member
Out of curiosity and my apologies if this has been addressed but is there enough throttle cable so the slide is/are allowed to fully bottom at idle? The idle speed screw fully out (anti clockwise turn direction) until that cylinder stops running altogether, same for both sides.
Ive had more than one instance where the cable hangs up the idle speed adjustment. That is, with the carbs adjusted, the outer cable should be able to pulled up until restricted by the slide. If the outer being pulled changed isle speed, that’s a problem.
Ive had more than one instance where the cable hangs up the idle speed adjustment. That is, with the carbs adjusted, the outer cable should be able to pulled up until restricted by the slide. If the outer being pulled changed isle speed, that’s a problem.
Other than the neutral light signalling you that the engine is safe to start, the wires from the alternator area have nothing to do with the ignition (points, coil, plugs, etc)......
12V to a 6V coil would yield a hotter spark (although it might eventually burn it out).......
IF your sparks are occurring at exactly the T to index alignment, your problem is either compression or fuel/air supply........
911hillclimber
Veteran Member
Thank you, I'm setting the timing using the buzzer on my DMV to F, and the closest I can get is about +/_ 1 deg or less either side if the F mark to the generator mark.
compession must be ok, reborn, Pistons to 2 thou clear and new rings with gaps around 10 thou, about as tight as can be?
Just maddening, and never again will I touch a twin.
compession must be ok, reborn, Pistons to 2 thou clear and new rings with gaps around 10 thou, about as tight as can be?
Just maddening, and never again will I touch a twin.
mike in idaho
Veteran Member
I put a little gasolene in a spray bottle, and spritz a small stream into the carb throat while it's running, if if the revs pick up you know it's a fuel problem .
So you're going to sell it and be one of those non-twin-owning members? Trust me, it's only THIS twin... if they were all like that, Richard wouldn't have 3 of them and we wouldn't have a website.
911hillclimber
Veteran Member
I've lost my can of EasiStart, so will try some neat fuel, but I cannot fathom why with all I've done it behaves like this.
my gold cab was just the same!
doubt my wife will want to see one again!
maddening for me.
my gold cab was just the same!
doubt my wife will want to see one again!
maddening for me.
Richard Pitman
Veteran Member
If I was relying on one of these as daily transport I might also get frustrated. For me, the 175s are just a hobby, and the various issues that arise are all part of the fun. My wife often asks 'Isn't 'that bike' finished yet ?'
My reply is that none of them will ever be finished, always something needs doing, would be very boring otherwise.
Now, computers, there's something to get annoyed with ….
911hillclimber
Veteran Member
Yes, of course it is just this CB175 that is....teasing.
My first one was irritating too and all in the same area, ignition/carbs. Everything else was easy.
I will replace the small battery with a giant motorsport battery that will churn anything over, so will have that sorted.
I have read countless forum articles on timing the bike...
People talk about the bike static timed to the LHS on the compression/firing stroke, but I thought this bike released spark on the compression to one cylinder and a 'wasted' spark to the other so it does not matter if the timing is set on LHS compression as you also check the timing on the other side 360 deg later or is this the step I've missed?
thus:
Set crank at T and the cam timed with the peg for the advance device at 6 o'clock. The 'O' on the cam sprocket is at 12 noon.
Adjust tappets on the LHS to 2 thou, 360 later, set the RHS to 2 though, rotate 360 to get back to starting point, advance pin at 6 o'clock.
Set points to 14 thou. using either of the 2 cams lobes on the end of the cam shaft/advance unit. I turn the engine so the points heel is between the lob starting and dropping.
Set crank to T with LHS on compression cycle, both valves closed, checked by the tappets being clear by 2 thou. (RHS tappets lifting valves, so tight), so crank at TDC.
Set points plate about where i think is right for static timing.
With the buzzer set on my meter, one lead to ground on the engine, check it buzzes. Disconnect condenser wire.
Place other lead on the points screw head that fastens the points spring and condenser wire.
Turn the engine 360 and see, when the buzzing stops, where the F line is to the generator reference line.
Adjust the plate position a million times to get the buzzer to stop as close to the alignment of the F line/generator line as possible. Recently I manage the position about 1mm or 0.5mm either side of the generator line of the F line.
I check it all after fully tightening up the clamp screws on the plate.
I now consider the engine electrically timed.
Now, is any of the above wrong?
Sprint mentions compression above. This worries me.
After the precise rebore with a new set of +0.75 pistons, 2 thou clearance (or 1 thou radial clearance) and new 0.75 Honda rings which gave a ring gap of 6 thou the block should be 'factory' fresh and yet the feeling of compression is not very inspiring.
I expected a good resistance when spannering-over the engine with the plugs in. I used a bit of oil to help ease the rings in on re-assembly and a compression test only gave 80 psi, both cylinder the same, engine cold, no carbs on.
The valves do not pass cellulose thinners, chambers hold full after 30 mins.
So, with new coil, condenser etc the spark with the plug out and sitting on the head domed nut is not strong but is a steady stream using the starter mother for 10 seconds to check. This is the same both sides.
Fresh 99 octane fuel fed from a small reservoir at the height of the fuel tank, no bends in the supply tube.
What can possibly go wrong?
My first one was irritating too and all in the same area, ignition/carbs. Everything else was easy.
I will replace the small battery with a giant motorsport battery that will churn anything over, so will have that sorted.
I have read countless forum articles on timing the bike...
People talk about the bike static timed to the LHS on the compression/firing stroke, but I thought this bike released spark on the compression to one cylinder and a 'wasted' spark to the other so it does not matter if the timing is set on LHS compression as you also check the timing on the other side 360 deg later or is this the step I've missed?
thus:
Set crank at T and the cam timed with the peg for the advance device at 6 o'clock. The 'O' on the cam sprocket is at 12 noon.
Adjust tappets on the LHS to 2 thou, 360 later, set the RHS to 2 though, rotate 360 to get back to starting point, advance pin at 6 o'clock.
Set points to 14 thou. using either of the 2 cams lobes on the end of the cam shaft/advance unit. I turn the engine so the points heel is between the lob starting and dropping.
Set crank to T with LHS on compression cycle, both valves closed, checked by the tappets being clear by 2 thou. (RHS tappets lifting valves, so tight), so crank at TDC.
Set points plate about where i think is right for static timing.
With the buzzer set on my meter, one lead to ground on the engine, check it buzzes. Disconnect condenser wire.
Place other lead on the points screw head that fastens the points spring and condenser wire.
Turn the engine 360 and see, when the buzzing stops, where the F line is to the generator reference line.
Adjust the plate position a million times to get the buzzer to stop as close to the alignment of the F line/generator line as possible. Recently I manage the position about 1mm or 0.5mm either side of the generator line of the F line.
I check it all after fully tightening up the clamp screws on the plate.
I now consider the engine electrically timed.
Now, is any of the above wrong?
Sprint mentions compression above. This worries me.
After the precise rebore with a new set of +0.75 pistons, 2 thou clearance (or 1 thou radial clearance) and new 0.75 Honda rings which gave a ring gap of 6 thou the block should be 'factory' fresh and yet the feeling of compression is not very inspiring.
I expected a good resistance when spannering-over the engine with the plugs in. I used a bit of oil to help ease the rings in on re-assembly and a compression test only gave 80 psi, both cylinder the same, engine cold, no carbs on.
The valves do not pass cellulose thinners, chambers hold full after 30 mins.
So, with new coil, condenser etc the spark with the plug out and sitting on the head domed nut is not strong but is a steady stream using the starter mother for 10 seconds to check. This is the same both sides.
Fresh 99 octane fuel fed from a small reservoir at the height of the fuel tank, no bends in the supply tube.
What can possibly go wrong?
GAP points at the spot when the "points heel" (breaker cam follower) opens them to their widest opening........012" to .016".......
Your fingertips should be able to locate the points opening "corners" of the cam.......
Your fingertips should be able to locate the points opening "corners" of the cam.......
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