How tight should the top end cylinder bolts be?

[Grover]

My 2002 CR125 had low compression, so I decided to look at the piston/rings/etc. I did my first top end removal. :yeehaw: The bolts putting both the top end and the head were VERY difficult to remove. I needed a 18 inch breaker bar in order to remove them. Is this normal, or did the previous owner tighten these too tight, possibly affecting the compression by compressing the gaskets too much?

Off topic already: What size piston is a 132 cc CR125?

-Chris

 

[reelrazor]

Did they 'break loose' and spin out by hand after that?

Did they look clean or corroded?

Doesn't really matter whether or not the guy before you did it right, as long as you do it right this time.

 

[Kav]

No that’s not normal, I don't think having the bolts too tight would change you compression any at all. The previous may have over tighten them, or the may have been corroded making the hard to remove. Just make sure that when you put it all pack together you torque it to specs

 

[marcusgunby]

No normal 18lbft is the normal torque i think.

56mm piston gives a 134cc.

 

[Grover]

Okay,

Piston size.. the first owner lied to the guy I bought it from, saying it was 132 mm (which is race legal??) It's actually a 134cc, I measured the piston at 55.75mm. Thanks people. The ring appears to be the problem here. I'll be ordering new rings, gaskets.