[300ex high compression piston] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

Pages:1

300ex high compression piston
(Click here to view the original thread with full colors/images)

Posted by: rybaij

I have a 300 and was wondering is it worth it to put a high compression piston in it. I was thinking like 11:1 with a stock bore. I'm looking for an inexpensive way to gain some mid to top end power. Another thing would i have to run race or high octane gas

Posted by: honda300EXtreme

hey, it will give you better throttle response, and a little bit more power, also if i were you i'd run high actane gas to prevent detonation

Posted by: Sjorge300EX

quote:
Originally posted by honda300EXtreme
hey, it will give you better throttle response, and a little bit more power, also if i were you i'd run high actane gas to prevent detonation

you DON'T need high octane gas for a 11:1 in a 300ex. The 93 from the pump is plenty. The piston is very easy to install and gives a decent amount of power increase over the stock piston. Great upgrade for about $100

Posted by: Cody_300ex

High compression is where alot of your power gains come from when you get an aftermarket piston. If I was you I would get .020 shaved off your head and the jug to get even more compression, which equals more power

Posted by: honda300EXtreme

quote:
Originally posted by Sjorge300EX
you DON'T need high octane gas for a 11:1 in a 300ex. The 93 from the pump is plenty. The piston is very easy to install and gives a decent amount of power increase over the stock piston. Great upgrade for about $100

thats what i ment, higher octane pump gas, theres definatley no need for anything higher, sorry about the mix up

Posted by: Sjorge300EX

quote:
Originally posted by Cody_300ex
High compression is where alot of your power gains come from when you get an aftermarket piston. If I was you I would get .020 shaved off your head and the jug to get even more compression, which equals more power

then you WOULD NEED to use high octane gas. lol

Posted by: Cody_300ex

quote:
Originally posted by Sjorge300EX
then you WOULD NEED to use high octane gas. lol

Oh yeah, I atleast run a 75-25 110/93 mix. Mostly 110 straight. Nothing under or it runs terrible.

Posted by: JIMFROMTEXCO

I had an .20 over 11:1 wiesco and it ran fine on 89.

Posted by: 2muchquad

My 300ex with the 385kit with a ACTUAL compression of 11.7 to 1 or so runs fine on 93oct.I tried race gas mix before but i came to the conclusion it was a waste of money.Results may vary with different set ups.

Posted by: Sjorge300EX

quote:
Originally posted by JIMFROMTEXCO
I had an .20 over 11:1 wiesco and it ran fine on 89.

well its not 87 so thats why. You may also have a high area of blended enthanal in your area. I tried 87 in my 300 once cause I got stuck with no gas in the middle of the neighbor hood and no one had premium, i will never even try it again.

Posted by: JIMFROMTEXCO

it would run on 87 but it ran like poo, and too hot... yes i belive my area does have higher amounts of ethanol as well

Posted by: bwamos

quote:
Originally posted by Sjorge300EX
you DON'T need high octane gas for a 11:1 in a 300ex. The 93 from the pump is plenty. The piston is very easy to install and gives a decent amount of power increase over the stock piston. Great upgrade for about $100

Agree 100%.

I also HAVE to run 91 octane (premium pump in my area, no ethanol) in my setup. But you would probably be fine with 89 at stock bore, cam, and ports.

Posted by: Sjorge300EX

quote:
Originally posted by bwamos
Agree 100%.

I also HAVE to run 91 octane (premium pump in my area, no ethanol) in my setup. But you would probably be fine with 89 at stock bore, cam, and ports.

yeah the ethanol really seems to help. When I got gas in places where it doesnt, my quad seemed to run worse. BTW, I was just.020 over high comp in my motor and I have 10% ethanol blended gas.

Posted by: dork

i think most areas allow up to 15% ethanol blend. any more and they have to tell you. the more ethanol you run the richer your jetting will need to be. oxygenates like MTBE were the same, they needed richer jetting.

Posted by: enduro400rider

not to steal the thread but since were on the topic of octane, what do you guys think about that octane booster? i have never tried it because i heard it was bad for your motor im just curious to see if anyone on here uses it and what they think of it.

Posted by: dork

from what i've read, its effects are minimal for most brands, like 104+. the cheaper stuff used MMT, which did bad stuff to the insides of your engine. plus, most brands don't specify how much a "point" of octane they increase it. it could be .1 or whatever, and usually not 1. race gas is definitely the best way to increase octane. the klotz octane boost is suppossed to be good though, but its highly oxygenated and you will need to increase your jetting. some use toluene or xylene but its not really cost effective if you do it all the time and you should add lubricants if you use it.

Posted by: N300exJ

Ethanol sucks *** for high tech/ hp engines. Just be careful with your jetting when you have that ethanol mix crap. It will lean out your engine a lil bit. thats why it burns cleaner. And octane booster does nothing at all. say you put it in with 91 or 93 octane gas. the highest the octane level will go is 91.4 or 93.4. Not even half an octane point. that stuff is useless.

Posted by: 250X_project

What he said^^^ He's exactly right. Octane boost is a waste of money.