Hi my bike makes a knocking sound when it is under strain,ie going up steep hills.I think the piston needs replacing. How much should I reasonably expect to pay for a new piston and a rebore,parts and labour included.Thank you

is it definitely piston knock, it may be pinking if you are not running on the super leaded petrol, mine knocks on standard unleaded.

piston and rings are about 185 pound and i dont think you can get a re bore only a chromium (sp?) replate so try super and make sure you have the right mix 70;1 or 60;1 to little oil will make it knock . super burns cleaner and faster so you can run a bit more oil

piston and rings are about 185 pound and i dont think you can get a re bore only a chromium (sp?) replate so try super and make sure you have the right mix 70;1 or 60;1 to little oil will make it knock . super burns cleaner and faster so you can run a bit more oil

running more oil lowers the octane. i would use optimax and 70 to 1

Most Rev3's do it. It is pinking. Remove the head and polish the top of the piston and the cylinder head (get some Autosol polish). Use the best petrol you can find. Use fresh petrol. Raise the needle a notch helps some bikes (but also makes other '4-stroke'... run rich). Check the air mixture screw is correctly adjusted.

Then when this is done..... just put up with it cos i never fully got rid of it on mine.

Ralph

Mine has the same problem and I solved it by raising the fuel level and optimizing the air screw. I tryed raising the needle but the mixture was too rich.

Your bike just need richer mixture. Now you have too much air and too little petrol..

Mine has the same problem and I solved it by raising the fuel level and optimizing the air screw. I tryed raising the needle but the mixture was too rich.

Your bike just need richer mixture. Now you have too much air and too little petrol..

I almost agree, I have the same bike and suffered the problem as described on the original post. I tried all the things described above and although it did make a difference, it didn't sort the underlying problem. The problem turned out to be a partial blockage of the pilot jet which required the jet to be removed and the foreign material pushed out with a pin. I had previously blown through all the jets with the airline and all seemed well but just goes to show its worth inspecting closely.

After the blockage was removed the bike ran better than it had for years!!!

Most Rev3's do it. It is pinking. Remove the head and polish the top of the piston and the cylinder head (get some Autosol polish). Use the best petrol you can find. Use fresh petrol. Raise the needle a notch helps some bikes (but also makes other '4-stroke'... run rich). Check the air mixture screw is correctly adjusted.

Then when this is done..... just put up with it cos i never fully got rid of it on mine.

Ralph

Ralph, if you clean piston and head is it enough take of just head? Not whole cylinder?