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That Baker Guy's CB360 project

Joined
Apr 19, 2022
Total Posts
29
Total likes
0
Location
Mississippi
I am far enough along with this project where i figured i need to start a project thread if for no reason other than my own documentation purposes.

74 CB360(G) looks to have been manufactured March of 74.

Seems I am the 3rd owner. last gentle man said it was last on the road ~2016 and maybe ran last year.

uCcPe0r.jpg
 
I'll use post #2 to list whats fixed so far an whats next

Quick image gallery for some progress pics

As purchased condition:


  • Seemed to be a complete bike, side covers in tact, just missing a battery.
    • overall just dirty. had sat out behind a barn under an awning for a few years.
  • Chrome is generally OK lots of surface rust some pits.
    • Front fender and L/H exhaust caught the brunt of the pitting
  • Electrically everything is functional except:
    • ignition circuit (starter button, kill switch (no power to points), points needed a good cleaning)
    • flasher relay
    • headlight high beam indicator light.
  • Gas tank was *GROSS* really badly rusted internally
  • Carbs were surely just as bad off as the bike bike looked (spoiler they were)
  • R/H fork mount cracked on triple tree
  • Throttle cable was frozen
  • Tires seem to be from this decade. very minimal dry rotting if any should get a season out of them.


Progress so far:



  • Gas tank
    • Etched and sealed with KBS Cycle tank kit. Really impressed with this product.
  • Petcock rebuilt with CMC's kit
  • Ignition system sorted
    • New YUSA SLA battery
    • points cleaned and timed via the timing marks
    • R/H control rebuilt, (starter button replaced from CMC, re soldered kill switch back together.
    • spark plugs appeared to be brand new NGK 8's
  • Fixed front brake
    • master cylinder was bone dry and stuck shut,
    • caliper was also froze.
    • was able to free everything up and do a quick shop rebuild enough to have a working front brake while moving the bike around.
  • Unfroze throttle cable/carb slides
    • was able to take off the throttle cables while i rebuilt the r/h switch box.
    • cleaned them up and lubricated and they came around.

At this point i confirmed the bike would fire, i had the tank back on and tried to push a little gas and starting fluid through the carbs. would only start with the starting fluid. even managed to ride it around the block before rebuilding the carbs completely.


  • Carbs rebuilt
    • Soaked each in chem dip for 24 hours each.
    • rebuilt with CMC's carb rebuild kit; as received it had #100 main jets (currently using 105 main jets) seems to be running really rich


Once the carbs were rebuilt the bike started almost immediately after the float bowls filled. very exciting to see. would even kick start easily.


  • Threw a new 530 roller chain on because i needed an easy win late at night.

With the carbs freshly rebuilt i decided it was time to start tuning the engine.


  • Cam chain adjust per FSM
  • Valves adjust per FSM
  • Re timed points via timing marks

It was here I experienced some frustration: i could not get the bike to fire after the above procedure. Sometimes the left cylinder would fire so I spent afternoons checking and re-checking my adjustments and couldnt find anything. Finally via another thread it was recomeneded to replace the spark plugs and so i went down to the hotter NGK 7 plug and it fired right off like it never missed a beat.

SO as of today I need to figure out what the next steps are.
 
To Do List:


  • fix start button (cmc replacement)
  • fix kill switch (rebuilt controls)
  • new battery (yusa)
  • sort out the gas tank (kbs cycle tank kit)
  • rebuild petcock (CMC rebuild kit)
  • rebuild carbs (CMC rebuild kit)
  • find air filters (CMC pods)
  • replace flasher relay
  • replace high beam bulb
  • replace drive chain (revzilla 530 roller cut down to size)
  • fix cracked triple tree
  • unfreeze throttle cables
  • unfreeze front brake master cylinder
  • replace exhaust bushings (lots of exhaust coming out of the middle joint.
  • remove god awful crash/highway bars
  • replace starter relay (works after some coaxing once its sat a little)
  • fix tachometer (NOS cable on ebay)
  • rebuilt master cylinder
  • new brake pads
  • 3d printed gauge isolators
  • carbs synced
  • exhaust gaskets
 
Sorry i have taken the first three posts to kind of document where i am at.

So i am kind of at a sort of cross roads at the moment.

I need to start tuning the bike a bit.

In my head i am having trouble with what order these need to happen in

  • proper timing with a light etc.
  • carb sync
    • I have a few concerns here.
  • compression test

What takes priority here?
 
Not a problem, post away.
Bike is at least complete and in reasonable shape for almost 50 years old.
Carb sync is the last thing to do after a full service, tappets, timing, oil change, check centrifugal filter and modify oil transfer piece (if you remove clutch cover to check filter, usually good for 20~30,000 miles though)
Try and find something to 'soften' the seat before use, they are pretty expensive to replace even if seat covers are available.
How did you repair cracked top yoke? (I've seen them 'repaired' with JB Weld and body filler, neither of which actually work)
TIG welding would work and probably be stronger than original if you know (or are) a good weldor)
It's a very common issue on 360's as Honda saved probably 0.001 cents by removing the special washer fitted to the same fork on 350's
You may well be wasting your time on throttle cables, once the inner wires rust up they generally start to fray internally if you do manage to free them. I would just get a new 'opening' cable and leave out the closing cable (in fact, on my bikes, I always remove the closing cable and have since 1978 without any issues.)
 
apologies post 2 is supposed to act as a check list. but i cant figure out how to strike through text on this forum yet.

When you mean soften do are you referring to the foam or the leather? we did use a good leather cleaner on the seat but eventually it will need to be recovered anyway.

the cracked yoke is not yet fixed; i have a co-worker who is going to take a shot a tig welding it. and then i'll break out my powder coating setup to re-coat it.

Currently i have a couple zip ties wrapped around it; only to attempt to relieve some stress from the lower fork mount while I move it around the garage.

once i can get the bike running, idling etc smoothly i will rebuild the front end all at once; wheel bearings, fork springs, seals, replace grommets on the gauges, head bearings, triple tree welding etc.

good advice on the cables. when i rebuild the front end i will look into just using the open cable.

zBVxMpm.png
 
Yep, something to soften the vinyl.
I've had seats that were great with vinyl still soft and others that looked and felt great great but a few days later just started cracking up which can be 'quite annoying'
I think the heat in Florida has something to do with it though, garage not too bad but shed gets way too hot and 'cooks' things
 
Not a problem, post away.

Carb sync is the last thing to do after a full service, tappets, timing, oil change, check centrifugal filter and modify oil transfer piece (if you remove clutch cover to check filter, usually good for 20~30,000 miles though)

i have timed the bike using a test light and the marks on the generator. Should i use an inductive timing light to time the bike before syncing the carbs? is there a good write up out there that shows how to do that with the different advancing positions of the advancer.
 
If the advance (ATD) unit is working properly and points cam not rattling around your good to go.
Even if the springs are slightly stretched it won't over advance but may not reach full advance (the main advantage of using a strobe is to make sure advancer works properly going full range)
Be sure to sync carbs below 1,700 rpm, adjust idle speed as needed to keep in range (as carb sync gets closer the engine speed often increases as one cylinder isn't fighting the other)
 
BTW, change the brake lines, they should be done every 4 years but I have seen people using them even when surface is pretty badly age cracked. (35~40 years old)
OEM brake lines were overbuilt to a very high standard in my opinion.


i saw an old post on the other forum about carb sync adapters? Are you still making and selling those?
 
So when i initallity re-assembled the carbs i put 105 jets in I am running pod filters at the moment. my stock boxes are not usable, very clogged. (100's were in the bike and seem to be factory per the 745B). i also noticed my R/H carbs butterfly valve wasnt centered in the throat enough to where i could do a good bench sync. i didnt think much of it as i figured i would be taking them out again anyways.

After starting the bike and running for a while and even putting the hotter plugs in, it seems i am running rich (very dark colored plugs, lots of carbon) and seeing some back firing. my graphite exhaust gaskets were also non existent.

So I took the carbs back apart,

i was able to center the butterfly valve and do a better bench sync. put new 100 jets in and focused on making sure my POD FILTERS and intake manifolds were sealed good. and fixed the exhaust leaks.

overall the bike is running a lot better. the idle adjustment knob does have an effect on idle speed. previously it did not. but lowest idle i can achieve is 2k rpms and i get a lot of stutter around 3k when driving around the block.

From what i have read high idle seems to indicate running lean which makes sense given the pod filters and 100 jets however the plugs are still very dark BLACK!

havent attempted the carb sync yet as i am still waiting on hearing back from PJ.\

i did attempt to run the stock air boxes with the 100's to see if the idle would drop but it wont hold any idle with these clogged filters.
 
It's best to re-set float levels to 21mm, I never got the Honda settings to work properly, even in the 70's.
'Pod' filters (especially cheap pods) will always give a problem during transition from primary to secondary main jets around 4~5,000rpm when it gets too rich to run properly.
 
Wanted to post a quick update.

I spent my summer plant shutdown vacation tearing apart the front end.

Once i get that done i'll tear into the rear and get it cleaned up. I hope to ride this thing around towards the end of summer.

I cleaned and rebuilt the forks, waiting on getting the triple tree back from the welder and i should be ready to throw new head bearings in and move on.

When rebuilding the forks i took the time and drew up a 33mm fork seal driver in fusion360 and 3D printed it in PLA instead of trying some sketchy seal install method or spending $$$ on a tool.

below is the link to the thingiverse page in case somebody else needs it.

https://www.thingiverse.com/thing:5432599

https://imgur.com/wAvhxGs

Z2qCZNF.jpg


JXErCYt.jpg

wAvhxGs.mp4
 
it worked very well, .5mm oversized ID gave a great fit and as you mention the plastic is non-marring on the fork tubes.
 
Didnt realize its been a few months since i posted last.

I was going to post a quick update but figured i would take the time to document the build.

I have gotten the bike to a point where it is somewhat rideable. Giving her the italian tune up has really shaken a few things loose and highlighted what needs to be addressed.

Completed in the past few weeks:


  • Triple tree tig welded (it didnt hold)
  • Triple tree powdercoated so it looks good for now even though its cracked still
  • new wheel bearings front and rear
  • rebuilt the front master cylinder.
  • new brake pads for the disk
  • installed taper head bearings on the front steering stem
  • Carb Sync
  • new carb boots
  • new condenser

As i mentioned I have been riding it a bit around the neighborhood just to see what is going on with it.

two things stick out to me and they might be related.

Firstly

i noticed that it would idle fine at start up with no choke; when i would ride it for say 15 min or so and get it hot it would not idle at all.

If i adjust the idle screw so that the bike idles when its hot; it will idle at ~ 4k when cold.

I am not sure what to make of this.


Secondly

I was noticing some.... power discrepancy. I felt what felt like really good acceleration early in the rev range and then it would die off unexpectedly.

I finally noticed today that it seems like the R/H cylinder dies at about 4k RPM's. So really good acceleration early on then it just is kind of meh.


When i rebuilt the carbs i noticed that one of the diaphragms had an attempted repair to it. at the time i let it go to see if it would run like that. i popped the top off the carb today and found that the repaired diaphragm was in the R/H carb so it seems the diaphragm perhaps may be the culprit as to why that cylinder dies higher in the rev range.

The left hand diaphragm looked fine. no tears or anything. Should i replace it at the same time? I have 1 on order from Common motor.



Pic below. Would this diaphragm be causing the cylinder to die or would it be a potential problem with the advancer?


carb.PNG

bike.PNG
 
Getting this bike out on the road has really got me excited. It seems to have plenty of power and rides great. kind of surprised at how fun it is to ride.

Once i get these two issues above sorted out i can start diving into the carb tuning.

I am running pod filters and some shorty mufflers so i will have to do some plug reading I'm sure.


On the To Do list out side of the engine:

  • New super bike handle bars. (CB400F?)
  • Rear shocks
  • New upper triple tree.

Need to figure out a headlight solution. Mine is pretty cracked and i would like to switch to LED for the power savings on the old electronic charging system.

I also 3d Printed up some replacement isolators for the gauges. The old rubber vibration isolators were really dried up and were not holding the gauges in place... lots of vibrating.

I took some measurements and drew these up in CAD; Printed in TPU a softer filament, not a rubber replacement but it compresses and does its job well for dampening these gauges.



isolator.PNG

on bike.PNG
 
I replaced the suspect diaphragm and now i have all the acceleration in the upper range now. the idling issue after it heated up is all gone.

I did replace both diaphragm at the same time with the common motor replacements and really recommend them. very easy process. cut the plastic off and slide them on.


with both diaphragm replaced now i went back to sync the carbs again. The left hand cylinder does not die when i close the pilot air screw all the way. after searching the forums; i pulled the spark plug boot while running and there is no change to the idle at all. When i adjust the R/H screw or pull the boot the bike dies.

So in short its only idling on once cylinder. i expect this has always been the case even before i replaced that diaphragm.

I can see spark across the points on the L/H points and the plug fires when i have it out of the engine, held to the cylinder head as ground.


I am assuming this is a timing issue.

I went to clean the advancer this evening and it seems fine. nothing sticking etc. so i quickly cleaned and lubed it and threw it back in.

When re-assembling i noticed i had the stock 312 advancer which seems correct for my bike and year but i noticed the points plate has 369 stamped on it. going by the listing for charlies place electronic ignitions a 369 indicates it is a CL or CJ points plate.

Would the mismatch between the points and advancer cause any timing issues?

Where would i find a new points plate? i cannot find anything online.
JaU89zV.jpg
 
When it's idling (on one cylinder) is the points cover on it? If so, (and even if not) you need to rearrange the left points wire terminal so it looks like this.

5H6N3kg.jpg
 
Thanks, I did make sure to check and see if the points were grounding to the cover or not.

As i mentioned i did get spark to the plug as well when out of the engine.

I have a new set of points that i am going to throw at it and will re-wire as you mention.

Do you have any concern with the mismatched 312/369 advancer/points plate?
 
As long as the point fit the plate correctly and provided the plate can still be adjusted as needed to achieve the left side timing adjustment within the .012" to .016" gap as specified by Honda (the right side is done with points gap, of course) then the plate should not be an issue.
 
so i have verified the timing and re timed the points however i still cannot get the left cylinder to fire at idle. I know it fires once i give it some throttle.

What else should i check?

valve clearance?
what about the carb?
I tired swapping the coils by just pulling the wires out and swapping but the bike wouldnt start at all then.
 
I imagine it's already been mentioned but have you checked carb sync and voltage at coil when running?
The points plate and advancer isn't a problem unless you fit an electronic ignition that uses stock advancer, the pivot shafts for points cam are different lengths between a 312 and 369 although I think all later models had the mismatch
 
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All of this transpired when i tried to sync the carbs with the gauges and noticed that when i dial the idle air screw all the way in on the left cylinder it doesnt affect idle.

when closing the idle air on the right hand cylinder the bike dies, as expected.

I have not checked the voltage at the coil. what should the voltage be at idle? battery?
 
Yeah, expect battery voltage at coil, or at least very close. you need a minimum around 10v or it will miss fire above 6K
Remove the fuel screw completely and check tip, if it's been overtightened the tip may be broken off and stuck in carb body (if badly stuck, very difficult to remove but sometimes just 'falls out' with some 100+ psi air from pilot jet hole)
 
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