WR426 engine worries!

Hey all

I have a 2002 WR426F and recently decided to take the clutch side cover off to find the cause of a loud metallic knocking noise when the engine is under no load..

I have found that my noise is being caused by the large gear on the back of the clutch basket having 1-2mm of movement against the gear on the crank..

BUT.. My major concern is now finding that the small gear underneath the right hand side of the clutch basket is very loose, along with with input shaft into the gearbox and the selector shaft having quite a bit of backwards/forwards movement, AAnd the rectangle shaped drive for the water pump located inside the counterbalance shaft is very flogged ( almost round )

Sorry about the long post but do my concerns for these problems legitimate or are the 400/426 just sloppy motors and nothing to worry about?

I really don't want to have to part with this bike but if the repair bills are going to be big I may be better to sell it while its still chugging along

Thanks in advance

Time to pull the motor apart and rebuild everything.


It should not be making ANY clunking noises.


If you wait much longer, you will have castisrophic failure, destroying the cases.

Thanks for the quick reply

This is what I was worried about, time to offload the old girl I think :-(

While the loosened driven gear is an indication of general wear, there's no evidence in that alone that it's time to "pull the motor apart and rebuild everything".  If the splines on the crank are not damaged by the gear rattling around, you should simply be able to replace the drive gear (if necessary), tighten it back down, and be OK.


The driven gear slack is due to the built-in torsional cushion assembly being beat up.  On the 426, that means you'll need a new driven gear/basket assembly because there's no available parts to rebuild it.

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