Very small plating flake on intake side of cylinder, OK to run?

[Studboy]

I pulled my cylinder off and I have a small (about .5 cm deep and 1 cm long) piece of plating that has chipped/flaked from just below the main intake port.

The rest of the plating looks perfect, the bike has never seized or overheated. The hone marks can still be seen all around. The plating right below it looks like it is still attached solidly. I couldn't see any wear marks from the plating on the piston or rings that I pulled out of the bike.

My question is, is it OK to just clean up the cylinder and reinstall? Am I going to run into any problems as long as the plating doesn't continue to flake? I don't want to have to replate right now.

Thanks.

 

[GhostRider32]

Just curious, which bike is it?

 

[Studboy]

The 2002 YZ250.

 

[jumpingjoe628]

If it is on the intake side I would be wondering what caused it, because usually its the exhaust side that will go first from all of the heat there. On my 02 CR 250 I got a rib in the center of the exhaust port that doesn't get plated so the piston goes from that, to the plating over and over again heating everything up and scored the piston a little. Thats what happened to mine and it wasn't bad also. Through time I changed the piston like 3 times and it kept getting worse each time so before the 4th piston I got it re-plated. I feel much more confident about my engine now.

 

[dirt bike dave]

If it is on the intake side I would be wondering what caused it,.

Intake side damage can be caused by inadequate lubrication; possibly not warming the bike up enough before putting it under load.

The theory is if you put a load on a cold two stroke, less of the fuel is vaporized by the engine's heat. The incoming liquid will wash the intake side of the piston.

Of course it could just be a defect.

 

[Rcannon]

Richard, take it into Lindsay. They can tell you in a second. My feeling is no. Dont use it. The wasted Cr cylinder I took to them had three of the sports you describe.

Watch egay for a new cylinder. I have also had success finding dicounnt Yamaha parts and giving south valley a chance to match them!

 

[Studboy]

Thanks guys. I don't know what caused it, but I doubt that it was improper warm up or lubrication. I am pretty careful about that kind of stuff, I am leaning more towards manufacturer defect.

I have a good cylinder on the bike right now, but for some reason it really isn't as fast as the other one. The old piston didn't burn down or anything in that other cylinder and it didn't show any excess wear marks, I just noticed it when I was cleaning the cylinder last time to reinstall it so didn't.

 

[RM_guy]

It could just be a bad spot in the plating from the factory. I'd send it to US Chrome to get replated--a lot cheaper than a new cylinder and you'll keep the same porting.

 

[Studboy]

If I were to run the cylinder, would it continue flaking or would it be fine? It didn't seem to wear the previous piston or rings very badly. We are taking a very small (I almost didn't notice it) flake here.

 

[RM_guy]

It could continue to flake and the exposed aluminum would get worn away fairly quickly and then when you did have it fixed it might have to be built up with weld. If it’s a very small area and it doesn’t continue to flake it may last a long time. I’d just worry that if it flakes in one spot, when’s it going to start flaking somewhere else?