Just posting this to let everyone know that a CBR900RR (93-99) Manual cam chain tensioner is a perfect fit to the NC31 400SF. My stock tensioner was getting a bit noisy, so bought a manual one and no more rattly chain!

Only real issue is adjusting it as you have to do it whilst running. Basically tighten the tensioner finger tight, start the engine and back it off till you start to hear some chain slap then tighten till it goes quiet then lock it up.

Engine should be a lot more responsive afterwards. Mine picked up a whole heap of part throttle response but my tensioner was pretty well stuffed.

Nice one, dies this fit all models of CB?

Not 100% sure, Provided the tensioner gasket is part number 12194-HC5-740 then it will fit. I matched the part number up to see what other models fit.

I have the NC31 part numbers list and went from there. Should be able to do similar with later models. I'd assume that all CB400's with the NC23E engine would be the same though.