Piston scoring?

[beta250rrowner]

When I was chasing my electrical problems, a bolt fell down into the skid plate, so I removed it and removed the exhaust as well.

I took the time to look at the piston with my camera and I'm not sure what I'm looking at but does this piston look scored? The previous owner said he put 80 hours on it, I don't think it had a new piston in that time and I've got about 15 hours on it. I don't want to do anything to it if I don't have to, I just wanna ride, but I was thinking the middle of next season I might do a top end refresh, if it needs it.

Point to note, I always run 5:1 ratio so it gets plenty of oil under my use.

Piston scoring by a a, on Flickr

[Clearvu1]

Do a compression test. If it's under 160 or so it's time for a new top end. Might be your problem right there.

[beta250rrowner]

Hi, if you are referring to the running problems I described in my other thread, I solved them, it was a loose cdi box plug. But does this piston look worn from the picture to you? I took the exhaust off to clean it and thought I might as well sneak a look at the piston while I am there.

The bike runs like a top at the moment so I don't want to mess with it if it's not necessary.

[mtdirtbag]

It does look like some minor scoring plus blowby. As clearvu indicated a compression test will tell you more without a lot of guessing, if it's low a piston change is not rocket science.

[beta250rrowner]

"minor scoring and blow by" thanks. The prev owner said 85 hours when bought. I have an hour meter installed (prev one died) so my schedule in my mind that (for my use as I am by no means a fast rider) that I will replace the piston at 50 hours. I am currently at 17 hours. As long as the bore is okay and undamaged I am happy.

[fletche36]

i hope you mean 50 to1 not 5 to 1 ratio. that wouldnt be good

[beta250rrowner]

Yes mate 50:1, 100ml 2t oil for every 5 litres of petrol.