Jump to content

Time to change my piston?


Recommended Posts

What are some of the signs in a 250 Two stroke when its time to change the piston? I have been lazy this year and haven't kept track of how many hours it has. Just what are some key things i should look for to know if its ready yet?

Link to comment
Share on other sites

Take off the pipe and take a look at the piston. If you see a lot of black below the rings, that indicates that there is blow by and new rings would be a good idea. If you see any scuffing or wear marks, it's definitely time to pull it apart and replace some stuff.

Or just change the piston for the hell of it so you know exactly how many hours you have on it. Not to mention the extra snap of a fresh top end.

Link to comment
Share on other sites

With my bike, I noticed the kickstarter seemed to go down a little easier and the bottom to mid power was a little sluggish (two strokes actually have better top end when compression goes down a bit). The problem is that it happens so gradually you don't really notice it until it's really worn and you could think it's just a jetting issue. The best method is to do a compression test with a fresh piston/rings, write it down and continue to monitor the readings over time. When you get a drop off of 10-15%, then it's time to do a top end.

Link to comment
Share on other sites

if my bike has 200-210 for compression. think my piston is good??

Two stroke or four stroke? On a smoker, that's good, don't know about a thumper. Also, it's the rings that really determine the compression test. Generally speaking, you do both piston/rings since you don't pull a top end off that often, so might as well, but on a smoker if you're racing and changing rings with a 5% drop, you can re-use the piston a time or 2, just pull the jug, slap new rings on, and bolt back up with a fresh base gasket. I wouldn't use a piston for more than a 100-150 hours or so (but I know guys who have).

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

×
×
  • Create New...