South West Bikers | Motorcycle Forum

meganall wrote:i've got a few shims for a zzr6 but should be the same at 4.8 mm so if you need a couple let me know you could be waiting ages for them to get them in

ZZR600 shims are 7.48mm diameter which is a common size for most things these days. The engine should be totally cold, if you do shim a warm engine then you need to go slightly larger on the clearances, if the clearance is 0.15mm then set for 0.18mm if a warm engine. This doesn't apply to a hot engine, just a warm engine, if it is too hot to work on then leave it for several hours to cool down. Before removing the cams make sure the engine has been turned to TDC on cylinders 1&4 and all the timing marks line up, then cable tie the cam sprockets to the camchain. Remove one cam at a time, be aware on some engines the camchain can fall from the crank sprocket, some have a guide casting around the underside of the crank sprocket some do not, if yours is one of the type that does not then using cables ties is often a waste of time, as it will drop off the crank. Most engines that have the camchain on on end of the crank will not have the guide casting, this allows the camchain to be changed without splitting the motor, if yours is like this then you ill need to rely on the timing marks to retime the cams. When checking the clearances after installing new shims make sure you rotate the engine several times to alolow the shims to settle before checking them. If you cannot get the exact clearance you want then always aim slightly larger, as over time the clearances will close as the valves recess into the seats, if you go tighter you'll be redoing them a lot sooner than if you go larger.

I did mine on the zx9r last year and found it pretty straightforward, the only thing which took time was working out which shims to swap around.Get a few pieces of paper and mark everything out so you dont mix up your bits when you lay em down.Oh and make sure you double check all your measurements and the camchain when reassembled cos I managed to jump a tooth the first time
A magnetic pen thingy helps a lot too