Hey
I've been thinking of getting a 10.5:1 or 11:1 piston for my 300ex. What kinda power gains do they produce? Is it even worth the hassle?
Mike

 

10.5 is the most to run on pump gas. Compression adds torque like a bore not much HP. It will pull harder off the bottom. A cam would help and you'll have the top end off any way. Just build it up. Compression hurts top end due to increased resistance. Cam 150, piston 120, gaskets 50, oil/sealants 15, machine work 80. Go 1-3mm over.

 

Thanks for the info.
Any suggestions on what brand of cam to get?
One more question on having it bored out. What do i have to bring/send to the shop when having it bored? Just the cylinder, and piston?
Mike

 

i just got my web cam in, and I really like it!! i can tell a big difference.

www.webcaminc.com

 

"Compression hurts top end due to increased resistance."

What??? Why would resistance increase as rpm's increase? Compression remains the same as rpm's increase.

You will see a big gain from a high compression piston. In fact, Many believe that it is the single most important factor to increase performance in engines, especially four-strokes. I did it, and it made my machine rip. Unlike what the poster said above, you will see a gain throughout the powerband, including top end. I can hit my rev limiter now, before the JE piston, I couldn't.

ogre

 

Hey 400EX'r;
I noticed you said "tricked stock carb". Have you done anything to the throttle springs on it?

I have a TC XC cam on its way (should be here today, was supposed to be here 4 weeks ago). Did you have a problem getting your cam from Tom?

Thanks, Nick

XC 400EX Too much too list, too much spent

 

Webcams are probably the best. They have been around forever. They are pretty cheap too.

I suggest calling up www.rittercycle.com and ordering the cam and piston from him. Its 195 for a cam(with heavy duty valve springs) and 95 for a piston. He has it all in stock, and it will be shipped out asap..i got mine in 2 days!

as for 10.5:1 being the highest, i think you could pull 11:1 with high octane pump gas. I always ran 87 in my stock 300ex!

 

Thanks again for the replys.
I think i'm going (to be on the safe side) with a 10.5 piston and probably a webcam, and a modded CDI.
Thanks again
Mike