12.5:1

[timmersam]

I am looking at getting a 450r at the moment and i was wondering, if I was to get a 12.5:1 piston what type of gas do I have to run? Can I run premium or will I have to mix?If I have to mix what octane will I have to mix with and at what ratio? Also if I get an 04-05 who makes a good piston for these years?

Sorry for all the questions and thanks for any answers.

Sam

[d3ktrix]

Most people say you can run 12.5:1 fine on 94octane premium.

I went with CP 12:1 just to be safe.

CP and JE pistons seem to be the top picks for 04-05 bikes.

[ss440ex]

Just had an engine rebuilt at j-hracing.
He machined a 13:1 down to where I can run 93 oc pump fuel.
Works good!
He can get ya more info.....

[XXXRACER165]

If your getting (remember) a '06 & up model, they already have a 12:1 piston inside and run rock solid on pump gas (premium). But for the year your getting I'd say CP too.

[GPracer2500]

Originally posted by timmersam
....if I was to get a 12.5:1 piston what type of gas do I have to run?....
There is no universal answer to that question. There are too many variables involved. What works for Joe Blow on his bike in his conditions with his pump fuel may not apply to you.

--The other parts of your engine will matter (cam, exhaust, jetting?).
--The specifics of the premium pump fuel sold in your region will matter (can you get 94?). Even beyond the reported octane rating, different pump fuels can behave differently in our engines. The R+M/2 octane rating system used for pump gasoline is far from perfect.
--Your riding locations will matter. High elevation? Low elevation? Low traction? High traction?
--Your typical riding conditions will matter (temps? humidity?).
--Your riding style can make a difference.
--How dead nuts accurate is the piston manufacture's static comp spec in your particular engine? Probably it's very close--but how do we know? Unless you measure everything yourself, you don't.
--Even your ability to detect detonation when it's occurring can factor into it. If you can detect deto in your engine and "ride around it", you may be able to get by with a lesser fuel. Someone else who isn't sure if there engine is deto'ing or not should not try and run a borderline acceptable fuel. I've seen several circumstances where someone's engine would knock under certain conditions and the owner had no idea it was happening.

Some of those things won't be big factors; others will be. But even the little things can matter in this scenario because I'd guess a 12.5:1 450r piston will be borderline even with the best of pump gas in the majority of riding situations. I know for my particular situation, there's not a chance in hell I'd assume my premium pump would be ok. I'd test it just to make sure, but I'd be surprised to find my premium pump gas was up to snuff for a 12.5:1 piston in my riding conditions.

$0.02

[timmersam]

Would there be a very big difference in power between 12.1 and 12.5? Im willing to mix it there is.
Thanks alot

Sam

[XXXRACER165]

None or very little power diff between the 2

[timmersam]

Thanks thats what I needed to know.

Sam

[d3ktrix]

Originally posted by timmersam
Thanks thats what I needed to know.

Sam

So what did u decide on? 12:1?

[timmersam]

Yes I am going to go with 12:1. I also want to get some other motor work done, any suggestions?
Thanks for the help,

Sam

[XXXRACER165]

Get a Sparks Cam and pipe:)

[timmersam]

I am a very big fan of Sparks and was thinking about getting there cam and piston, but I really want to try a Dasa pipe to see what its like. I am thinking about getting it ported and polished, does this give good power gains? I am looking to build this quad with the most power I can with out running race gas.
Thanks for all the responses!

Sam

[d3ktrix]

The sparks cam is supposed to be the same exact thing as the 02 CRF cam, and u can find those for around $100.

Yes porting gives very good gains on these motors if its done right.

If u get an 05 putting an FCR carb on it is also a great addition.


I'm also building for the most power I can get on pump gas.
Today I just put in my CP 12:1 and fired it up a few min ago =)
My next mod will be an FCR carb, then head work.

[XXXRACER165]

Dasa will be good too. Besides that I'd say your set!

[timmersam]

Sounds good ill post picks when I start building one, I am hoping to have one in the next month or so.
Thanks for all the replies!

Sam