Topic: Primary chain tensioner replacement

[jaytee-nz]

I'd like to replace the primary chain tensioner in my CB750 but I assume there is no way of doing this without splitting the cases (which I don't want to do) ?

[dave500]

do you have a twin cam engine?

[jaytee-nz]

Hi Dave - no it's a 1974 K4.
I'm quite sure the cases have to be split but you never know, some clever person may have worked out another way !

[dave500]

nics post has disappeared?you looked at a manual for that bike?see if you can find the section on the primary chain tensioner?you sure you don't mean the cam chain?

[Bodi]

The tensioner bolts to the inside of the bottom case, I don't think there's any way to get it out with the cases together.

[PeWe]

K4.... CB750? The answers are dependent on this vital information.
There are tons of information about this and exactly how to do it. Just search.

Replace the prim chains at the same time which can be done whith cases apart crank shaft liftened. Replace the cam chain at the same time with it's tensioiner.
Repairing an old engine will start a domino effect....bearings, clutch plates w springs, all chains with tensioners, valve job/new valves with cut seats, complete gasket set with ALL o-rings and seals on all shafts...

My CB750 runs very silent with new chains, all are heavy duty versions. I think the HD prim chains run more silent than OEM. Cost 3 times more though...

[Jerry Rxman Griffin aka MuthaF'er]

Not available from Honda.

[flybox1]

I'd like to replace the primary chain tensioner in my CB750 but I assume there is no way of doing this without splitting the cases (which I don't want to do) ?

why?  is it all chewed up?   Get a good look at it with the oil pan off?
yes, the cases will have to be split(upside down, and take the bottom case off)
doing this can be the beginning of an expensive journey 
with the engine out, you can and will find all sorts of things to upgrade/repair 

[PeWe]

Check the manual about the primary chain slack... limit is max 70mm measured with oil pan removed, case vs tensioner. New chains usually 65mm.  Old tensioners in the engine have bekelite whells instead of rubber
My HD chains from Classic Cycle City had little bit tighter 64,5-65mm direct when installed.

My engine run very smooth and silent with new chains and tensioners....Not the usual CB750 rattle, much better.

[jaytee-nz]

Thanks for the responses guys. I was only considering replacing the tensioner as a precaution but now that I've measured the primary chain it's well within the 70mm limit so I'll leave things alone.