Q. I have a '97 Honda Fireblade RRV. In May I rode up to the BMF Rally two-up but I didn't realise that the chain was running too tight over bumps and when accelerating.
It's now making a 'clattery' sort of noise when the engine is under load, mainly in third upwards.
I suspect the outer bearing but if I strip it down and the damage is not blatantly obvious how can I be sure that¹s the problem, and is it possible to replace it in situ?
Christian Thomas, email
A. A tight chain puts a load on the gearbox output countershaft and in particular the outer bearing.
This is a large and strong bearing which is a press fit on the shaft. For this reason, it is only available as an assembly (Pt. No. 23220-MAS-000; RRP £251), which means fitting involves an engine strip.
So, how to make sure it is the bearing? Remove all the covers to access the chain and sprockets. Look for tight links in the chain, worn sprockets (hooking of the teeth) and the chain running true on the sprockets.
Then to check the bearing; support the bike with the rear wheel off the ground and free to rotate.
With the ignition off and the gearbox in neutral, turn the rear wheel and listen to the bearing behind the gearbox sprocket (a workshop trick is to put a long screwdriver to your ear and touch the casing.
The sound is transmitted up the shaft to your ear). If the bearing is making a 'grumbling, rumbling' sound, it needs replacement.