[My New Engine Mods!] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

Pages:1

My New Engine Mods!
(Click here to view the original thread with full colors/images)

Posted by: hondapro300EX

Just got back from my local shop and went crazy on parts. Ordered a megacycle race cam. New valve springs. Port And Polish.(Only $100. Good friend is the only reason so cheap.) 12:1 compression piston from megacycles. Sounds like a good setup to me so I just got it done. Bad on money but man what a power difference. CAN"T WAIT!

Posted by: chapmanmd

Youre gonna love the Megacycle cams. Which grind are you running?

Posted by: hondapro300EX

I just got the race cam. But grind is the best for bottom and mid. Need to know as soon as possible so i can call shop back and tell them. Unless other wise i don't know which one i got. Need help fast!

Posted by: chapmanmd

Megacycle has 4 grinds, I think, for the 300ex. Their "all around" cam is good in the woods and such. If youre going all out MX, go for the third one. The fourth one is a good TT grind for all out top end.

You sure you want to go as high as 12:1? Good with race gas, hell on starters. Just my observation.

Seriously, if youre going with the race grind cam, porting, high compression, etc, youre well on your way. Now put a good exhaust on there and to tear some stuff up!

Posted by: ontarioracer#33

ya chapmanmd is right you are better off going 11:1 and shaving the head thats what i did and have had zero problems and it runs on pump gas, i add octane boost though just because im racing

Posted by: hondapro300EX

Is there any power difference in the 12:1 and 11:1?
And shaving head. Never seen done. Can you explain.

Posted by: chapmanmd

Yeah, there is a difference between 12:1 and 11:1. Just depends if youre willing to spend $6 - $10 a GALLON for race gas. Some guys can get away with 12:1 on premium pump gas. Unfortunately, Im not one of them.

Posted by: hondapro300EX

Oh well. I only get to ride 2 times a week. Be different if i didn't have 3 jobs. Im young i guess.
I want all the power I can Get! Like everybody else. Getting tierd of this ***get saying crap. Just want to see his face after i blow past his as&

Posted by: chapmanmd

Dont know whose ***** youre blowing past, but GIT R DONE!

Posted by: Blue250X

sounds like a real beast! How much more of a power increase is there between 11:1 and 12:1??

Posted by: humblesquirel21

im putin in a powroll 336 cam and 11-1 srp high rev box already have a yosh pipe edle brock carb h@n filter lid off (with outerwears) and a ebc clutch any ideas to what kidna power i can expect ??? new chain and sproket to 14-36 or 37 ( i bought 2)

Posted by: 2muchquad

i run a 385 kit and a 11.5 to 1 je piston with .020 takin off the heads and it runs fine with pump gas.also my starter doesnt seem to have trouble crankin it over here in this cold ohio winter season.i would say 12 to 1 is the limit with pump gas.i also have a oil cooler as well.also keep in mind 12 to 1 it may seem a bit high but with cam overlap it rwont be quite that much.high comp is where you make your money on a 4 stroke,regardless of what you may have read.sure it may be more wear and tear on your crank but...so you may need a new rod kit every 4 years instead of 8 on a 300ex