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Manual or Automatic Tensioner ???


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I'm collecting parts to rebuild my 78 GS750 engine and need some advice about the cam chain tensioner.

Should I replace the standard automatic one or fit a manual one???, what are the advantages/ disadvantages of both, one thing is the cost of a genuine automatic one (£150 plus :o)

Also I don't think the last o.e.m  one worked that well as when i striped the block there are score marks each side of the cam chain tunnel that look like the chain was flailing about side to side, although that could be down to poor maintenance.

Also while I'm on the subject how often should the cam chain be checked/adjusted ???.



Edited by Mouse
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If you assume the tensioner is original then the spring will be 40+ years old and can be assumed to be Well Slack! GSXR engines tensioners are well renowned for soft tensioner springs at much younger ages ! With those you can just replace the spring for less than a tenner! Checking on Alphasports shows they are available for the GS750 and less than $3 ! ! !

Check chain every time you check the valve clearances - std. procedure - if you can pull the chain off the sprocket and see a gap = its time for renewal! Its just like the final drive chain and sprockets. . . . just smaller! 

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Unless you have a tuned motor I wouldn't bother with a manual tensioner, just put a new spring on the OEM one. You can easily put to much tension in the chain with a manual one. Have heard of the OEM ones sticking and not doing there job.

Clean oil and well service engine (y)

Had a manual one on my gs1000 and ended up putting a OEM one back on 

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Hi Thanks for the input, 

21 hours ago, Gixer1460 said:

If you assume the tensioner is original then the spring will be 40+ years old and can be assumed to be Well Slack!

Pretty much spot on, engine has done about 60 thou which seems to be fairly accurate as i had some old mot's, but as my granddad used to say it looks like "it was rode hard and put away wet".

This is what i found when i took the block off.


So looks like the chain was not under that much tension.

Thanks for the link about the spring, didn't realise it could be replaced, when i took the whole unit off it was put in a bag for later examination, so one of them on the shopping list, also going to renew all the other camchain parts but having a sit down now as just found out the price of the rear tensioner, looking at £350 plus  :o>:(


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13 minutes ago, Mouse said:

 sit down now as just found out the price of the rear tensioner, looking at £350 plus  :o>:(


Them cam chain blades are not cheep for the oem did the same for my GS but fell lucky and found some new ones on eblag from the USA as a clear out for 1/2 the price and that was with the post 

Worth if you're not in a rush to trall the net ;)

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Was hoping for one soon as need to get the engine rebuilt.

bit worried though as even N.O.S will be over 40 years old, can one of that age be trusted ???, I know the one i  took out of the engine is 20 years and that the bike was dry stored for nearly that long, but that one has small fracture lines in it.

Maybe the fractures are due to it drying out as no oil has been circulated, also "new" one's will have been indoors ( I hope) and wrapped in grease paper.

Well off to trawl tinternet for a few hours (y)

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  • 3 weeks later...

Thanks for the link, very useful,

think i will follow peoples advice and stick to the automatic one and rebuild it :tu

On 10/13/2020 at 1:40 AM, BigT said:

My opinion on your barrel wear is that someone took the tensioner off and never released the plunger when reinstalling

You could be right, but if so I wonder why the chain didn't jump of the sprockets and trash the engine ???

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