? on standard bore JE piston

[Quadracer5]

Hey guys, I was just throwing around a few ideas for my 400, and I have a few questions. 1.) Is the standard bore JE 10:8:1 piston worth it? I'm not ready to bore the cylinder yet, I've only got 40 hours or so on the ex. I've mainly owned 2 strokes, so does the standard bore, high compression piston help quite a bit in a 4-stroke? I'm looking for torque mainly.

2.) How well does the 400's head respond to port work? By opening up the intake and exhaust ports, does it work well? And how does it work out with the high compression piston.

Thanks guys, just playing with some ideas in my head.

Kyle

[Ex'r Marlin]

Do you have an aftermarket exhaust? The reason I ask is because going to a 10.8 to 1 compression may cause your atv to "bog" some without one, mine did.

Otherwise, yes, going with a higher compression piston does make a noticeable difference, and to me is worth it versus going to a larger "cc" piston for the money.

Good luck!

[Quadracer5]

Yes, I have a Pro Circuit T-4 slip on. Thanks for the info, I am leaning towards the standard bore pistion for now. I can't justfy boring the cylinder for no reason. Thanks.

Kyle

[Quadracer5]

Anyone else have an opinion? Thanks.


Kyle

[Texan32]

Well, there is an old saying "there's no replacement for displacement" But in your case, I wouldn't do it. If your cylinger walls are still lookin good, i WOULD stick with standard bore.

About the porting. I don't have any porting. But after reading countless posts, the consinses here is that porting does help, but its REALLY noticable when you go big bore and stroker.

Also, if your looking at the poiston, you might want to thing about a little bit bigger cam. The hotcam stage 1 is supposed to help on the low-mid range

[2000ex]

Follow this thread, you will find some good info.....PLEASE hone the cylinder if you are going to move forward with the stock bore, I learned the hard way :o

http://www.exriders.com/vbb/showthread.php?s=&threadid=1576

[Quadracer5]

Thanks for the link 2000ex. Very useful information there. And yes, I will have the cylinder honed before I install my new piston. I think I will go with the XR cam also, seems like a lot of people do and they like the results. Do you have to run race fuel, or mix with your setup? I need to be able to run on 93, race fuel is not readily available here. Thanks. Also, the XR cam just drops in right?

Kyle

[Doibugu2]

There was a thread today that said that they did not see a lot of gain from the XR cam. I believe I also read somewhere is that it is real similar to the stock cam. I also believe that the hot cam is actually a tad cheaper, like $20 or so.

[Quadracer5]

Yes, I read that thread. But I also remember back in the day, when a lot of people were running the XR cam with good results. That was before a hotcam was an option, but still. I'm not sure on the cam yet, but I will definatly be getting a JE 10:8:1 standard bore piston. Thanks.

Kyle

[bmw500hp]

PowerAll in California suggests really (no need to port) standard bore applications with mild or mid / low end cams.... maybe exhaust clean up...optional.

They state that a stock ex-head is fine to 416cc and a (mild) camshaft....Porting necessary when these factors are exceeded.

They have been around quite a while.....Texan 32 has stated the same...