cutting out after piston install

[Blkmaroman]

I just finished installing a 10.25to1 wiseco piston in my warrior and now if my rpm start to go up a little high it will cut out really bad and i cant go any faster. I installed a 160 main jet and put 92 octane in her and still just cuts out bad. Im replacing the spark plug next week to see if it does the trick and im gonna also mess with the fuel screw and see what it does. Ive checked my cam timing like 5 times and its spot on perfect. Any other ideas?

[JOEX]

Too rich? What's the stock main jet size?

[Blkmaroman]

the stock is 145M

[JOEX]

Pipe, Air filter, lid?

I don't know how the Warrior reacts to jetting but i'd say you're too rich.

[JasonP]

Ok. First start by figuring out what circuit your on by throttle postion by problem.
0-1/4 throttle .. fuel screw, pilot jet and air jet
1/4 to 3/4 throttle.. jet needle
3/4 to full throttle.. main jet.
So pretty simple.
If this is happen at full throttle postion then I would say that you are to rich if the bike is studdering in the upper rpm band. Back off until it goes away and you should be fine. The richer you get the lower the rpm the studder will come on. The leaner you get the later the studder will get and the engine will start to run cleaner and rev more free.

[Iliketogofast]

It's jetted too fat. Main jet needs to come down a size or two.

[Blkmaroman]

Its got a k&N filter, holes in the lid, and the stock exhaust. So i need like a 155 Main jet then?

[JasonP]

I'm not really sure what jet you'll actually need for this type of setup but I'd get a couple as there usally pretty cheap.
Anywhere from 147.5 to 155 to everything inbetween.

[Iliketogofast]

Get all of the sizes in between 147.5 and 155. Jetting isn't a bolt-on affair. You need to tune.

Here's what I would do. Buy all of those jets, try them all until you find the one that makes it run better. When you find one that makes it ridable, install a fresh plug and ride it for 45 minutes to an hour, with as much full throttle as possible. After your ride, pull the plug and look at it.

Tan means good. Kind of like a cardboard color, maybe a bit lighter. Perfect.

Black or wet means rich (jetted too high)

White or very, very light tan means lean (jetted too low).

Now say you ran the 147.5 and it was too lean, but the 150 is too rich. That's what the air screw is for. Adjust it until you get it right - Turn it in to richen it up, out to lean it out.

And that concludes your jetting/plug reading 101 class. There are other things to look for, and it is possible to determine the ratio on each circuit (slow, needle and main) but you just need to get it running right at the moment, so don't worry about it.