New Port and Polished head, Quad only starts cold.

[karatekid14]

Okay, here's the deal. I have a 2007 electric start. I have an HMF pipe, Stage 2 Hotcam, No air box lid. It was jetted for it and ran great. Always adjusted my vavles every few months, cleaned my air filter regularly, quad ran like a clock.

I bought a brand new head from Honda, got it ported and polished, got KibbleWhite Valves and their HD double springs put in it. I bolted it on and this quad screams. But.....

PROBLEM: It only starts up cold... if I drive it around for 30 minutes and try to start it again, I'll kill the battery before it fires. If I wait for it to cool down it'll fire right up then. When it's on and running, it runs good. I know most of you guys are going to tell me it's the valves but I've checked them three times. They don't move. And it sometimes will hick-up. Like I'll be giving it consistant throttle and it'll skip, like I have water in the fuel or something.

On a side question with the valves, should I be still using stock clearance measurments with this engine work, since it's not exactly stock? I'm using .16mm for the intake and .28mm for the exhaust.

So next thing I was thinking was the jetting. It's ported, so more air, my fuel to air ration must be off. So I pulled the plug, it is a light tan, maybe too light tan... It should be a dark tan / light brown color right? Here's my jet sizes: 165 main jet, 48 pilot jet (long flat head jet) and 75 on the other jet (one that looks like a stubby flat head screw).

Any suggestions guys? Anyone have this problem before and knows the fix?

[Scro]

I assume this is a 450r? What is your decompression set at? Did you set it with a feeler gauge or compression test?

[JOHNDOE83]

porting allows more air to run through your motor and allows fuel to burn more efficiently, anytime you change air intake, you need to change jetting.

Id think, you could change the pilot jet and solve the problem.