2-stroke rattles

[mopower440]

--------------------------------------------------------------------------------

I just bought a 1998 rm125 and noticed it has that 2-stroke rattle (The rattle they make when it needs to be bored out, too much clearance). Wondering what to do since it has the nikasil plated bore in it, i cant afford to buy a new cylinder. I hate to just chance it and ignore it because i dont want the piston skirt to break, had that happen on several older bikes.what should i do?

 

[TimberPig]

Have you pulled it down and measured the piston and cylinder, to determine if the parts are actually out of spec? That would be a good place to start, as the bore may be fine, but the piston is shot? You could have other issues, but without tearing it down and inspecting it, you're only guessing at this point.

 

[mxmoto19]

my bike had a rattle and i found that it was my wrist pin

 

[mxmoto19]

also does it rattle when rev it or is it always there

 

[mopower440]

well, every other 2-stroke ive had has broken the skirts off the piston when they start to get the rattle like this, due to excessive clearance..the cr125 i have did the same thing wheni bought it, so i tore it down and had it bored out and now it doesnt have the rattle..The rm has that plated bore so i cant do that..

 

[2strks4evr]

pro-x sells micro oversized pistons works very good.u need to mic. the cyl.

 

[rmc_olderthandirt]

If you have excessive clearance between the piston and cylinder, and it didn't start that way after the last bore job, and it isn't the piston at fault, then you don't have a plated cylinder anymore!

I wouldn't expect the piston skirts to wear, so if they have been chaffing then it could only be against the cylinder and it will be damaged as well. The plating is very thin, so if the cylinder has worn due to normal ring wear then the plating is all gone.

Rod