Cam Question

[JP400ex]

I originally did not plan on making any motor mods to my KFX so I bought an HMF slipon pipe. How would it effect my power if I put a 12:1 JE piston kit in and Intake and Exhaust cam in without changing out the stock header???

[AceLtz]

you really dont need to put a 12:1 JE piston. If you simply change the base gasket to a drze base gasket it will bump your compression to about 12.5:1. the drze gasket is .010" and the stock is .027" so you get more compression. It also costs around $20. as for the header. Id always reccommend to get a header because an aftermarket header is larger than the stock which allows more air out.

i really dont know what the gains would be with the cams and the higher comp. and having a stock header but id say get an aftermarket header so youll have a full exhaust and be set up and not have to think about it.

[rrguy]

Where are you wanting more power.

Raising the comp will help low end & offset low end loss from adding a ex cam. Intake will help low to mid. exhaust cam will help top.


The piston will be fine with stock header. You should notice some improvement with the intake cam, but you will not get the full effect of the exhaust cam with a stock header. I don't know of any dynos comparing this.

[Kovatch]

AceLtz.. I do not mean to refute what you said, I respect you as a person, but I beg to differ about the gasket. I am in Ohio and I know people at both Wiseco and Cometic. Just from what I have heard from them, Wiseco offers a 12.2:1 high compression piston. If you add Cometic's DRZ base gasket, you will arrive at the 12.5:1 compression. I am not familiar with JE product lines/what they offer. This may be false but does JE offer a 12.5:1 piston with the DRZ base gasket? Or is the JE piston really 12.2:1?? Like I said, this is just what I have picked up on through my friends at both Wiseco and Cometic.

As for power gains. I have changed out both of the cams, high Wiseco piston with DRZ base gasket, and I have a slip-on E-series. Unlike your possilbe set-up I have my head ported, polished and 3 angle cut valve job. I noticed a big difference in performance. I have not changed the header just because money is short. I think you will definitely feel a difference with new cams, and piston. If you want to maximize it all, get the head done and P&P.