08 l/c 90 need help

[RapKor]

Just re-built (freshened up) my sons 08 l/c ported motor, went with oem piston and rings. Got motor together ran great had 125lbs compression, figured comp gauge was probably screwed up, raced this weekend ran awesome son said it has never ran better, did a comp test tonight after I took it off the trailer, differnt gauge showed 125 pds. Everything I have read said that 125 is too low, this motor has about 2-3 hours total run time on it can someone tell me if this compression is to low? machine ran great son ran 2nd,2nd and 1st in his 3 moto, we are now 2nd in pts with 2 races remaining (6 pts out of 1st) would really hate to see him screwed because of a mistake I made. Can someone pls tell me what the comp should be on an 08 l/c 90. wwhy would the comp be so low after a re-build, piston was installed properly. Thanks

[bulldogfallon]

What is squish clearance?

Also---What does the dome(inside) of your head look like?

Std compression dome has a steeper slope design and the high compression version is a flatter dome design (like an ash tray)?


Std comp set up would be 130 to 135 (gauges vary)

High Comp (165lb to 185lb)


If your cylinder needs a hone or a bore then you could lose compression...

[bulldogfallon]

I think the results and the vote of confidence from your rider speaks for itself.


Let me know what you find out.

Thank you

[RapKor]

More of a steep slope to the head, cylinder looked great so I did not have it honed, ( did not have one that size). Only fresened it up because it had been run for 4 races with nothing done to it. I do not know what the squish is and I am not sure how to tell. So do you think I should leave it alone or pull the cylinder and hone it? Thanks again

[bulldogfallon]

Your compression is close with that head....

How about getting a high comp head to gauge the improvement?

I may have a pull off one you can try...

If you like it...keep it...if not send it back

[RapKor]

That would be great! Would I need to re-jet or anything with a different head? Thanks agin. We are racing next weekend and he has been doing so well (3 wins in 5 races! 1st year racer.) i would just hate to see him lose the championship because of my lack of knowledge!