Hello there, I have 315r with piston slap. It wasnt to loud and only on tickover and low revs. I took the engine out this morning and took off the head and cylinder. The piston and barrel look very good with no signs of any wear, scratches or scores. The gudgin pin is noticably worn and small end has a little play, up and down movement, and there is some movement, very little on the big end. Now here is my dilema, I know that a new pin and small end will improve things but am I risking it by not changing the crank aswell and then if I change the crankshaft I should probably do the whole lot , thanks

Hello there, I have 315r with piston slap. It wasnt to loud and only on tickover and low revs. I took the engine out this morning and took off the head and cylinder. The piston and barrel look very good with no signs of any wear, scratches or scores. The gudgin pin is noticably worn and small end has a little play, up and down movement, and there is some movement, very little on the big end. Now here is my dilema, I know that a new pin and small end will improve things but am I risking it by not changing the crank aswell and then if I change the crankshaft I should probably do the whole lot , thanks

the noise you describe (low rev) sounds like excessive cylinder to piston clearance, where a bad rodbearing will make more noise as you rev. the piston may not appear worn, recomend to measure clearance to determine if needs new piston, a noticibly worn wristpin is a sign of possible dirt injestion.

the noise you describe (low rev) sounds like excessive cylinder to piston clearance, where a bad rodbearing will make more noise as you rev. the piston may not appear worn, recomend to measure clearance to determine if needs new piston, a noticibly worn wristpin is a sign of possible dirt injestion.

Yes, you are correct. This bike has been neglected big time. While taking it apart this morning I discovered dirt on the carburetor opening after i removed the airbox and the air filter was in a terrible state. While looking closer today I put the piston into the cylinder and there is a little movement on the skirt part of the piston. Also the only markings on the top of the piston are IN and what looks like X7 . Is this the original ? I thought i should see A,B or C stamped on it. Maybe I will just need a new piston kit for it. Thanks for your reply

I believe I have a similar issue with my 98 315r (purchased late 2010)as you have described. I have been holding off replacing my piston as the bike still seems to still run okay. My question is, should I do the top end sooner rather than later, and if I wait am I just making things worse in the long run?

Seem to recall barrel is marked on N/s below inlet manifold A,B or C. Get Piston to suit and is the change part as bore doesn't wear unless damaged. Dont think rings and piston kit are silly money so if apart and you have concerns worth a swap. 315s are a little nosiy at tick over. A bit pinky!!! Best of luck

Ya mine was running fine aswell, even when i bought it six months ago I wasnt sure if there was a noise there or not and I have only riden it around the garden a few times since . Good compression , starts on the second kick from cold, Its just that it needs wheel bearings and a few spokes and a bit of loving and that made me have a look inside and I thought I might aswell sort that out now while Im at it

Seem to recall barrel is marked on N/s below inlet manifold A,B or C. Get Piston to suit and is the change part as bore doesn't wear unless damaged. Dont think rings and piston kit are silly money so if apart and you have concerns worth a swap. 315s are a little nosiy at tick over. A bit pinky!!! Best of luck

Yes A is marked on the cylinder under the inlet, But i think i read here somewhere that i could put in a B because of the wear the cylinder would have. Im not sure

Ya mine was running fine aswell, even when i bought it six months ago I wasnt sure if there was a noise there or not and I have only riden it around the garden a few times since . Good compression , starts on the second kick from cold, Its just that it needs wheel bearings and a few spokes and a bit of loving and that made me have a look inside and I thought I might aswell sort that out now while Im at it

Using any fuel other than high octane unleaded seems to make them sound a bit knocky.

Using any fuel other than high octane unleaded seems to make them sound a bit knocky.

To be honest I never put fuel in it, Its still running on the fuel it came with. I think I will go ahead and order the piston kit and hope for the best

Yes A is marked on the cylinder under the inlet, But i think i read here somewhere that i could put in a B because of the wear the cylinder would have. Im not sure

Yes definetly go to the next available piston size when replaceing. The cylinder will have some wear for sure. I went from the origional B piston to an A when replacing mine on my 98 315 and it worked well. Mark

Yes definetly go to the next available piston size when replaceing. The cylinder will have some wear for sure. I went from the origional B piston to an A when replacing mine on my 98 315 and it worked well. Mark

IS THIS CORRECT? I thought A was standard and B and C were next sizes up

Curious about all this as well. My 01 has a bit of piston rattle at idle.

My Cylinder is marked A. Havent torn into it yet to see what piston is in it.

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