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CD175 engine

Cleaned and reringed the pistons this morning. Removing and refitting new rings does not get any less stressful, but got there in the end, rings right way up, in correct order. Pros make it look effortless, referring to the CB350 race engine video.

Some foreign body has presumably passed through the one cylinder at some point in the engines history, found this mark on one piston top. Obviously not life threatening, as it was filled and hidden by carbon layer, so must have covered a few miles in this state. Not ideal, but it's going back into the engine.

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A little spot like that will be fine, nothing that would compromise the piston's structural integrity. Slight carbon collector as you mentioned but not enough to cause issues in the future.
 
I love the refitting of CD pistons. The slope on the barrels makes it a doddle compared to some bikes.
Yes, Honda was brilliant in putting such a nice taper at the bottom of all their cylinders. A large overbore often eliminates them and then the need for a lot more patience or a quality ring compressor comes into play.
 
If that was the right piston, that mark would be at the plug hole. Maybe a prior helicoil job? Or a crude piston stop tool mark?
 
I was going to rebuild the clutch side of the engine this afternoon, in between dog walking and cooking dinner, but thwarted by oil pump gasket in aftermarket gasket set, it simply doesn't look remotely like the correct part. I have a sheet of gasket material, so I'll have to cut a new gasket. Hole punch somewhere in the shed.

Thinks - didn't someone once post printable patterns for all the 175 gaskets ? Just had a quick scout round, can't find them either here or saved locally.

Found them !

 
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Only problem with those gasket scans is that the oil pump gasket scan is same as the one in my gasket set ie completely wrong, so no help there. Went ahead and made my own gasket.
 
Only problem with those gasket scans is that the oil pump gasket scan is same as the one in my gasket set ie completely wrong, so no help there. Went ahead and made my own gasket.
Richard, Here is a gasket scan from the NOS kit I bought which is a little late now, yet for future reference. The kit was listed as a CD175 gasket kit on the package and only has the single carb paper gasket in the kit, so possibly correct for your application???img002.jpg
 
Thanks AD. I just checked and it does fit the CL175 correctly which I was now wondering, since there are different styles???
 
I've worked on so few 175s since leaving the Honda shops that I only know what I see in the parts fiches these days, so I'm no help.
 
Thanks, yes, that looks like the gasket that I've just made. I think I've ( and possibly other posters ) have come across this issue in the past, all the other gaskets in the set being correct, but the paper oil pump gasket wrong.
 
That oil pump gasket. One in the scan above is the same as the one in my 175 gasket set, so I guess he ran into the same problem. My photo shows a vertical 175 oil pump with the duff gasket. As I said, I've cut my own now, from some gasket sheet.

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Your pump is a little different design than the sloper one for the oil outlet and mounting point is different.

Moot point though. :)
 
Clutch side all assembled now. The oil pump lock tabs were fatigued beyond use, so I used a couple of generic locking washers. Not elegant, but they'll work. In fact, I do question why Honda bothered with lock tabs. When the chimps put this engine back together they'd used the oil pump lock tabs on the cam chain tensioner, and just did the oil pump bolts up very tight. Engine had clearly run like this for some time. Home made oil pump gasket visible around edges of oil pump.

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Should have taken a photo of the bottom end before closing the cases, but it is nice and clean in there now. Slightly excessive use of Honda Bond though :unsure:


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As an experiment, used this paint on the side cover. Just heated using my heat gun at present, still debating whether to try baking it in the domestic oven. Coating seems pretty scratch resistant already. Paint came out darker than expected, I chose Graphite because in the past I've found Silver paints too bright. Blurb states that they cannot vouch for long term adhesion to bare aluminium, just have to wait and see. Not the end of the world with easily removeable side covers, more of a pain if I'd painted the cylinders or main cases.

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Richard if you have DupliColor in Britain then this is a newer engine primer that I have used a few times on bare aluminum with great results before the top coat of your choice. Good for 500F which covers the heat range of a air cooled motor and then some.

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I painted the alternator side covers yesterday. Later in the afternoon I was cooking the dinner ( we tend not to go out on a Saturday night, so we have Sunday dinner on a Saturday night - too much information ? ), and popped the covers into the oven at 160c along with the roast.

And I got away with it ! SWMBO is usually very sensitive to the 'nasty smells' that I bring in from the shed, but this coating was surprisingly odour free, extraction on full of course.

Finished result looks just the same as the cover that didn't get baked, but coating seems tough, stands up to the fingernail test. Worth noting that that is a CD175 sprocket cover, different to the CB/CL/SL part, extended to meet the CD full chain case.

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Got the side covers fitted, just temporary on the alternator side. Keeps the dirt out of the engine, and reassures that I haven't lost any parts. I may scrounge the electric start parts off the other spare engine, but need to get the top end sorted first.

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Looking a bit tidier than before

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The clutch actuator return spring was missing, and appears to be NLA, using the CMNSL part number to search by. However, after looking at various photos and fiches, I took a gamble and bought a 400/4 return spring, which looks as though it will do the job just fine.

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I kind of like the graphite looks.
I agree! I would have used that colour if I hadn't already used the silver finish. Nice and neutral with a flat finish that is just different enough than the original colour.
 
Spent a little while this afternoon trying to clean up the cylinder block prior to attacking it with the ball hone. ( Which sounds a bit like a medieval torture implement :oops: ).

In the past , someone had painted the cylinder fins with black paint. Much of this has flaked off due to poor preparation, and I'd like to get it back to bare aluminium. I'm not going to be too rude about the chimps this time, as I painted my own CB175 cylinders black, back in the day.

I've wire brushed and scraped, shoved 400 grit paper between the fins, got sore fingers and bored. Seriously thinking about getting some oven cleaner when I do the Christmas food shop tomorrow. I know caustic soda isn't good for aluminium, but if I'm careful it should be OK ???
 
I have heard of some one painting the cylinder head head of their car silver , and then having lots of problems with it over heating.
 
If you have access to a bead blaster then it will clean those fins easily. Taping the top and bottom areas with duct tape will solve any intrusion issues with the glass bead. I have a smaller table top cabinet and it has paid dividends over the years. Even a hand held unit can be used outside into a large plastic container to mitigate the overspray of beads elsewhere.
It does require a reasonable sized compressor though, which could be an issue for you???



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I just left the black hole parts engine sitting in a metal refrigerator bin covered with a hunk of plywood, full of gas for a few days then power washed it almost completely off. The remnant scraped out easily. I've got a couple quarts of used brake fluid too but not enough to submerge a cylinder or head. Hmmm.
Oven cleaner should be checked on frequently.
 
If you have access to a bead blaster then it will clean those fins easily. Taping the top and bottom areas with duct tape will solve any intrusion issues with the glass bead. I have a smaller table top cabinet and it has paid dividends over the years. Even a hand held unit can be used outside into a large plastic container to mitigate the overspray of beads elsewhere.
It does require a reasonable sized compressor though, which could be an issue for you???



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How many CFM of a compressor is needed for your table-top blaster ?
 
How many CFM of a compressor is needed for your table-top blaster ?
I’m not sure there, I never checked the spec. My compressor is a 30 gallon size floor standing unit @120 PSI and you get about 45 sec of blast time before the unit kicks in. It takes about the same amount of time to recharge again.
I have both that hand held unit and a slightly larger portable bead blaster the size of a large fire extinguisher too. These will operate longer, especially the hand held unit which uses less air volume it seems.
 
I’m not sure there, I never checked the spec. My compressor is a 30 gallon size floor standing unit @120 PSI and you get about 45 sec of blast time before the unit kicks in. It takes about the same amount of time to recharge again.
I have both that hand held unit and a slightly larger portable bead blaster the size of a large fire extinguisher too. These will operate longer, especially the hand held unit which uses less air volume it seems.
I understand. I like that hand-held blaster.
How many horsepower is your compressor;does the electric motor turn at 3400rpm,etc. ?
 
Again not sure it is 120V and can be wired to 220V also. I think it is about 6 CFM roughly and the motor is a couple of HP. It’s a 2 cylinder design in a V configuration and made in the USA. 😀
 
No compressor here I'm afraid, space and budget preclude such an item. Engine work slowed down, due to other 'priorities', helping her indoors getting the house ready for visitors. Bet Allen Millyard doesn't have those sort of issues ....
 
No compressor here I'm afraid, space and budget preclude such an item. Engine work slowed down, due to other 'priorities', helping her indoors getting the house ready for visitors. Bet Allen Millyard doesn't have those sort of issues ....
Understood. It is not a item most really need. I purchased mine years ago when it was much cheaper than today's crazy prices.
 
No compressor here I'm afraid, space and budget preclude such an item. Engine work slowed down, due to other 'priorities', helping her indoors getting the house ready for visitors. Bet Allen Millyard doesn't have those sort of issues ....
Besides tending to his hedgehogs, Allen does get a good amount of shed time.
Richard, just be glad she doesn't want to decorate your shed too!
 
Lost my cylinder honing virginity today, and like so many things, once I'd done it, wondered what all the fuss was about. :love:

I don't know if you chaps have the 'Fast Show' over there, but Swiss Toni would have had something to say about this.

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Not a show I was aware of until minutes ago. The picture isn't completely clear (at least on my pc) so it's hard to tell much detail. I always try to get a 45° angle on the crosshatch.
 
Got the cylinders fitted this afternoon without any drama. Except that I couldn't find my piston supports. Again. Second set that I've made. 5 minutes with a saw and some UVPC board had a third set made.

Spent the rest of my time tidying my work space a little bit, so that I'll have room to sit at my table to work on the cylinder head. It is filthy and partially coated with black paint, as well as the usual carbon in the exhaust ports and combustion chambers, so it will need a good clean before I go further. Oven cleaner was a partial success on the cylinder fins, most of the black paint removed from them. This was after trying some of this stuff, which turned out to be a waste of time. Hoped it might shift the stuck on cylinder base gasket, but had no effect, had to resort to scalpel and scraping.

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That cat is a real pest. We put out surplus dog food for the local foxes, but that cat often gets there first. The other night I was stood in our porch watching, cat already scoffing the food, fox approached. I was expecting the cat to back off but instead it went for the fox and saw it off. Fox is three times the size of this small cat, but clearly not very aggressive.

The hedgehog ( cat biscuit ) food is in a feeding station. I have had to restrict the entrances to this to stop the cat getting in, incredible the tiny gaps it can squeeze through.

This made it jump though !

 
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