How to preform primary chain inspection?

BAMotobuild

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Hello,

I have a 1982 cb750SC DOHC torn down. I'm inspecting major components before reassembly. I was curious if there is a validation / inspection for the primary chain length like there is for the cam chains? My primary drive train tensioner has some tearing to it on the outer most left side when looking top down when the pivot is at the bottom. pieces have been torn from the material.

Thanks!
 

amc49

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Easier to go by the miles on it. The Honda method of checking primary is quite wonky. It calls for you holding the chain on two 'primary' gears which are drawn in the manual like cam sprockets but there is no such part. One end of course is the crankshaft and you fasten it down solid and pull against it with 80 lbs. of force while simultaneously trying to measure to a dimension given that you have no such physical ability to repeat on your fixture there. It is obviously some kind of an elaborate factory setup for measuring the race bike chains. The max measurement is 5.16 inches but you have no way to repeat that as your centers they call for are non-existent.

The tensioner blades are always wearing crooked, there is really nothing to hold them straight and they warp sideways easily. I'd look at the crank and gear for even indentations from the teeth across the running faces. I don't think you will break the chain outright if the bike is not hot-rodded, it will simply get noisier.

I'd put new tensioner on it and make sure the outside running face of the chain is not chewed up to eat the tensioner blade.
 
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