I think im losing power

[400exmxracer]

So, I completely rebuilt my motor over the winter from the bottom end up, and its starting to feel like its not pulling as much when im riding. I don't know if its just because I'm getting used to the power, or something else. Please give me some ideas of things to check for slight power loss. Thankyou.

[CJM]

Check your compression. 100psi minimum.

[400exmxracer]

I have a wiseco 11/1 426 piston. What should the compression be?

[CJM]

Like I said, at least 100 psi.

[Zakradu398]

With an 11:1 in my 400ex when it was brand new I believe I had slightly over 200psi

[JOHNDOE83]

My 440 after some usage had 165psi when I installed my stage 2 cam.

Like they said above 100psi minimum, that is the baseline for any bore.

[Blodg]

I have not done a compression test yet on my 400EX but wow those numbers seen low. On my full race 492cc 350X motor I measured 270-280 PSI and on my mildly built 355cc 350X motor I measure 225-235 PSI. Or maybe my gauge is off? I will measure the 355cc motor again and then measure my 416EX after break in.

Those 400EX numbers are with the decompression removed right?

[Zakradu398]

yea, it could have been a little higher also due to extra oil in the cylinder when I put it back together.

[CJM]

Highest I ever read on my 426 was like 180psi. But baseline is 100 psi, anything around 100psi or lower needs at least rings.

[KKiowaTJ]

I dont know what kind of build you have, But maybe the clutches are too week. The warm weather possibly? Thus motor running warmer needing a thicker/different oil.
I have always noticed that no matter whos quad/bike it was, It always ran harder in the cooler riding seasons. Good luck either way