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Cam chain adjustment position early CB250/350

Windmill John

Veteran Member
Joined
Jun 4, 2022
Total Posts
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Total likes
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Location
East Sussex, England
Sorry ancientdad, tried a search!

I recall on my 500T needing a certain position for cam chain tension setting; 90 degrees past Left TDC?

Anyway, not my question; sort of. Does the early 68 CB250/350 need a similar procedure? Can’t see it in my book.

I’m guessing it does as I’ve just been for a ride after replacing my cam case gasket and I’ve obviously messed up; noisier.
 
The early 250/350 bikes used a hydraulic tensioner.....
I recommend you replace that with the later spring loaded type unless you are going for concours.....
 
I was lucky enough to get a later adjuster with the bike. But I’ve possibly tensioned in the wrong place.
I yesterday put the cam cover on, set the tappets again, but found I had to adjust my timing…
The bike is definitely noisier today, so I’d like to check tension again tomorrow and reset clearances, timing etc.
 
There is a position 90° past one of the TDC (can't recall if it's left or right cylinder) where all the valves are closed, the position you would have done the cam bearing cover gasket as well. That point puts no tension on either side of the cam chain so the adjuster can properly tension the chain.
 
The Common Motor video showing 350 cam chain adjustment instructs you to place the rotor 180 degrees opposite of what this Honda service bulletin shows.

It seems no one there has ever cracked open a factory service manual?
 
I usually remove the left exhaust and rt intake valve covers and they should both have movement. It's a very small window but not difficult to achieve
 
Wow Dale, I’ll say it again, thanks.

To get good movement in all four valves, I’d say I was up to 10 degrees left (counterclockwise) of the index mark, using the above posted Honda image/instructions, but it sorted out my issue.
Once I correctly adjusted the cam chain, all four valves were definitely looser than stock, feeler gauge didn’t touch the sides. All now adjusted, timing corrected back to where it was before my….. erm… error; very happy.
 
The Common Motor video showing 350 cam chain adjustment instructs you to place the rotor 180 degrees opposite of what this Honda service bulletin shows.

It seems no one there has ever cracked open a factory service manual?

It's what I've been saying for years, they have all the same information we do yet somehow tell people to do things the wrong way.
 
Hi all,
Just to be clear for everyone…the procedure described in the thread is purely about correctly adjusting the cam chain.
Correct valve adjustment is a different procedure (undertaken after adjusting the cam chain).
Cheers
Mike
 
...I can see the grimace on his face as he pushes his finger into his temple ;)

OMG. GRIMACE?? Waaay past that. I always thought this guy had more sense than CMC but clearly they must go by the same playbook.

Unbelievable... it makes you wonder why it didn't occur to him that since a hammer was required to remove the left cam cover, maybe he was doing it wrong... clearly didn't read that cute little manual he had, just looked at the pictures like we used to do with Playboy.

John, thanks for discovering yet another video banned from our forum.
 
I actually found Saturday’s Wrench not a bad series, although he does make a few slip-ups, including the screamer mentioned above (he does a nice job of videoing etc).
Sadly, much later in the series he gets the assistance of motorcycle mechanic to reassemble his engine - bit of a cringe when the mechanic deploys a knockometer (AKA a hammer!) to reinstall the cam end cap.
Cheers
Mike
 
I actually found Saturday’s Wrench not a bad series, although he does make a few slip-ups, including the screamer mentioned above (he does a nice job of videoing etc).
Sadly, much later in the series he gets the assistance of motorcycle mechanic to reassemble his engine - bit of a cringe when the mechanic deploys a knockometer (AKA a hammer!) to reinstall the cam end cap.
Cheers
Mike

I actually tried to watch that episode a year or so back when it came up at the time., and I couldn't get past all the face time the guy was giving himself as if he'd become some YT star. People get too carried away with being in front of the camera sometimes, the instruction is supposed to be the reason for doing it, not them becoming (in)famous. Glad I didn't get far enough to see that edition of "hammer time", I'd have been screaming at the monitor again.
 
I'm a YouTube star, I have two videos to prove it ;) I'll be signing autographs later, but here's one of mine. The cable blew my mind. This is just after I got the bike and bear in mind it is detached at BOTH ends.....

https://www.youtube.com/watch?v=iSHM0ZQYHDY

Wayyyy off topic now! Feel free to delete the post if you wish ancientdad.

Wow, that is one stiff cable. While listening to you it occurred to me... are grunts and groans subject to a British or American accent? :) Seems yours sound the same as mine.

BTW, your channel shows no videos so this one must be unlisted. I was hoping to enjoy the other one of the two.
 
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