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Discussion Starter · #1 · (Edited)
This past weekend I attempted to tune up my 1975 CB200 for the first time (have ridden it 600 miles since I bought it 8 months ago). Didn't manage to complete all the operations successfully or perhaps at all, but also didn't mess anything up (I think). After watching some common motor collective videos about tuning up a CB360, my goals were to adjust the cam chain tensioner, check the valve clearances, and dress the breaker points.

Made a little video to help me process just how much I have still to learn! Tried to correct some of the stuff I got wrong with text overlays-- constructive feedback and encouragement welcome:


I also had intended to replace the spark plugs, but did not have the correct socket. After reading horror stories of stripped or broken spark plugs creating a nightmare, I opted to leave them until the 18mm socket arrives in the mail. I similarly chickened out of removing the tappets because I don't have backups yet and wanted to ride my bike home at dinner time. But this lead to a mistake-- because I had no way of identifying which cylinder was in its compression stroke, I had a 50% chance of getting it in the wrong position for the cam chain tensioner adjustment. Now I understand that the pistons both move up and down in unison (one in its compression stroke and one in its exhaust stroke) and my single breaker point assembly fires both spark plugs and my engine uses the wasted spark principle.

todo for next time:
-order replacement tappets and gaskets before removing existing ones to check/adjust valve clearances
-remove spark plug and/or tappets to identify compression cylinder
-potentially replace spark plugs (although they seem way newer than the bike, amiright?)
-make sure to set the kill switch to "on" in order to use test light on breaker points (major *headdesk* for me)

Questions:
-Conflicting info on the position at which to adjust cam chain tensioner-- honda service manual says TDC, Clymer manual doesn't mention an engine position at all, and common motor collective video says 90 degrees past TDC. What's the deal?
-Where can I find a replacement part for the breaker points assembly? Having trouble finding a CB200 points assembly online. Bike has 10k miles, not sure of its service history.
-During this process, one of my spark plug boots came off its wire. It's a poor quality connection and I want to replace the whole wire (with something more sparkly, perhaps). In another realm, I'm great at soldering (DC hobby electronics), so I'm not afraid to either splice+shrink or attach directly to the coil (which would you advise?), but what does the connector look like? And do I need any additional parts? What's the difference between "suppression" and "copper core" ignition wires?

I'm super new to motorcycles but really enjoying the learning journey. I know I've just dipped my toe in the ocean and appreciate your expertise! :D
 

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Well done, kind of....
So as youve learned its a wasted spark 360 twin. It shares alot in common with the cb175's not so much with the cb360 so following the common motor advice for a twin points 180 degree twin will lead you astray
The pivitol point of adjusting the camchain is when the valves have the least or most even pressure on them, TDC in your case. At other points in the crank/cam rotation the cam is putting uneven pressure on the valves and there is likely to be less slack in the chain
Also it should be done on a warmed engine ( youll need gloves since the exhaust pipes are right there
I hope you topped up the oil
A block of wood under the center stand LHS so thd bike tilts slightly to the right ( but not so it will fall) will stop the oil draining from the cases
The tappit covers have oring gaskets theyre more robust than the paper gaskets the biggest risk is if a gorilla put the covers back on because they can break ( ive done it :()
When you put them back on they just need to be snug
You should get yourself a test light to adjust the points, they should be gapped ( as you checked) but also need to open on the F on the rotor ( next to the TDC)
Good to see youre having fun, keep it up
 

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Discussion Starter · #3 ·
Thank you!

So the cam chain adjustment is done warm, and the valve adjustment is done cold?

Thanks for the tip about leaning the bike right to leak less oil out of the case.
 

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Good work!
Nothing constructive to add, but a question for Simo, if you were to do cam chain adjustment when cold, what is the detriment vs hot?


Sent from my iPhone using Tapatalk
 

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metal expands when hot, different metals different rates of expansion.
The cam chain will be longer when hot so if you adjust it hot on TDC it will have the maximum slack available to take up,
Since its also true of the tappits the valve clearance will be reduced on a hot engine relitive to the actual temp
So setting the valves on a hot motor would make them too wide (noisy and damaging) if you used the the cold specs or would require a themometer and a known expansion rate so you could calculate the different gaps for different engine temps
 
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