11.5:1 compression

[crazyatvn]

I ordered my stroker kit and I thought for sure it was 11:1 compression and I was looking at the catalog again and it said 11.5:1.

So my question is can I run 93 octane pump gas on the 11.5:1?

Any help would be great.:(

[nosliw]

i know you can run 93 with 11:1 but i dont know about that extra .5. if you dont get any better answers then i would go with 50/50 mix of race and premium........

[crazyatvn]

I hope i don't have to the race gas is a pain to run and get all the time around my area.

[nosliw]

you think putting in an extra thick head gasket would make enough of a difference?

[tbargides12]

im running 12.5 to 1 comp and when i let my little brother ride it i run 93 and the rest of the time i run vp110 it dont run as good on the 93 but u can run it

[crazyatvn]

Where do you get extra thick head gasket. I think the xr400 is thinner right.

You don't get spark nock with 12:1 on pump

[nosliw]

yea i think the dirtbike one is thinner..... if it were me (and wasn't MY bike) i would just put 2 head gaskets on:D

;)

sorry man i dont know. you could run octane booster, but that will gunk up stuff from what i've heard on here. maybe it will just gunk up your carb and you can clean it every so often so it's ok?

[400exrider707]

No you should be fine with pump. Truth is its not even going to be that compression anyhow. Depending on what piston it is. The wisecos are way off. I have an 11:1 wiseco. The problem is that the piston was designed for the XR 400. The XR has thinner head gaskets, so when you put that piston in the EX with the thicker head gaskets then the compression drops. I've heard of people on here with 12:1 running pump so I would say youll be all right. If it starts knocking just get some higher octane gas. The higher octane will help it to run cooler too, so it might not be a bad idea for racing. Also DONT run two headgaskets!!!!

[crazyatvn]

The actual piston is a 10.8:1 ratio but with the stroker crank it will be 11.5:1.


I don't know what to do.

[cals400ex]

run a stock thickness cosmetic flex stee head gasket for your bore size. if you run one for a smaller bore size than what you have, it will just raise the compression. i would run that on pump gas. you should be fine in my opinion depending on your riding style.