compression question

[soonerlightning]

I am torn between an 11:1 je piston and the 12.5:1 wiseco piston. this will be going to a stock bore motor with minimal other mods. Which would you chose and why?

[250X_project]

11- better crank life and can use pump gas (premium).

12.5- more power than the 11.

I personally don't think I'd go above 12.0:1

[GPracer2500]

For your Predator, right?

What's the stock compression?

[soonerlightning]

GP yes its for the pred. Stock is 10.8:1 I have seen upgrades from 11:1-13:1. I am considering the 12.5:1 JE piston but I wanted a few opinions first. Bike will have full exhaust bigger carb and a clamp on filter. Other than that she will be stock

[GPracer2500]

Originally posted by soonerlightning
GP yes its for the pred. Stock is 10.8:1 I have seen upgrades from 11:1-13:1. I am considering the 12.5:1 JE piston but I wanted a few opinions first. Bike will have full exhaust bigger carb and a clamp on filter. Other than that she will be stock

I don't know too much about turning up a Pred. Consider that 12.5:1 may be beyond the reach of pump gas--especially when using the stock intake cam. A longer duration intake cam may get your dynamic comp back down low enough for pump gas to handle. I'm just speculating though. Keep looking for Pred owners that have done similar mods and ask for their experience.

Contacting a shop like Aaen Performance (http://www.aaenperformance.com/Predator.asp) might be helpful too. I know nothing of Aaen beyond what anyone can see from their website. I only mention them because they seem to offer lots of Pred stuff and not too many shops work heavily with Polaris products.

Good luck.

[pigpin]

just my two cents, unless u race the thing, 11.1, still run pump gas, cranks fine, and supper reliable, and it'll give that little kick your looking for. i learned the hard, went to a 426 with 13:1, stage III hotcams, full exhuast, K&N, i just wanted the baddest thing around locally, but for the power gain i got, and the cost of gas i have to run to play on trails.... i wish it was just stock sometimes. just depends on if you like to wrench or ride, lol

[Aceman]

The dollar-to-performance ratio just isn't there with the 11:1 piston. You're already at 10.8:1, I bet you would hardly feel the difference. Unless you're changing to a 12:1+ I don't think this upgrade is worth the cost.