Cam chain adjuster querie

Andy101

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Hi, please excuse the inexperience here, I’m usually involved with old Brit bikes… I recently acquired a 1980 XS650 se. It had previously been fitted with a Heiden big bore kit. It’s running rough as old dogs so Ive been working my way through it.
As per instructions I have been trying to adjust the cam chain. It is the E type adjuster with the locknut, 59mm adjusted and longer tension rod. However it does not have a bolt on mounting plate, the threaded adjusted screws directly into a boss cast into the barrels. It also does not have the copper or metal/rubber buffer washer. When I turn the engine over the tensioner rod moves in and out approximately 8mm each revolution. Is this normal? How should I best adjust it?
Thanks in advance.
 

gggGary

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You have correctly described the big bore kit cylinder tensioner mount method
Ideal rod movement is 1mm in out. More important than how far the rod end extends from or in the tensioner
 

Andy101

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Thanks Gary. Mine definitely moves shout 8mm per revolution. Can that be adjusted out somehow? Does it need the buffer washer between the threaded adjuster and the tensioner rod?
 

Andy101

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Thanks Gary but I may have answered my own question. I can adjust it until it has about 1mm movement but now there isn’t enough thread exposed to take the locknut and acorn nut… am I doing something wrong?
 

5twins

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Maybe the chain is worn and stretched out? On a stock machine with the bolt-on adjuster plate, having to turn the adjuster that far in is a sign of a stretched chain.
 

gggGary

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This BB motor was built, but has never run....
It's fairly cold it wasn't excited about being "hand propped" just sitting on a bike lift. :lmao:

xs650 bbcam  chain tensiioner.jpg
 

gggGary

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Start measuring parts, compare to 5twins exhaustive tensioner guide, confirm you have a matched set.
 

5twins

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Wow Gary, how come that tensioner rod is so far in? Does it just need adjusting because it hasn't been yet or is this the way those big bore cylinders end up?
 

gggGary

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Wow Gary, how come that tensioner rod is so far in? Does it just need adjusting because it hasn't been yet or is this the way those big bore cylinders end up?
Dunno, haven't checked the old in-out action. Jus' sitting since I got it back from Mr engine.
 

Andy101

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Anyway, another painful lesson, after messing about with the adjuster my valves are way, way out of sync with the rotor, I must have let the chain jump somehow. 🤬
I guess that’s a head off job?
 

5twins

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Andy, if you do have the 59mm long screw and longer type E plunger then you need the 3mm thick rubber/metal damper washer. With it, you won't have to screw the adjuster in as much (3mm less) to achieve the proper tension and hopefully that will provide room for the lock nut .....

CamChainTensioners.jpg


D-EPlungers.jpg
 

5twins

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Well, if the chain gets loose enough to jump teeth when the tensioner is backed off, it's definitely stretched out and in need of replacement.
 

Jim

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Anyway, another painful lesson, after messing about with the adjuster my valves are way, way out of sync with the rotor, I must have let the chain jump somehow. 🤬
I guess that’s a head off job?
If the adjuster can be loosened enough to allow the chain to "jump timing," then it should allow you to turn the crank the other way and possibly get the cam and crank sprockets back in alignment... that is once you've figured out the problem with the tensioner.

I think I'd at least give it a shot before pulling the engine.
 
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