I find this odd. My bike doesn't like to start when hot. I'm wondering if you guys could help me in the right direction.

Here's what I got from one end to the other: It's an '09 with a KDX snorkel, Uni filter, Mikuni TM33 carb 132.5/40 jets with the pilot screw dialed in so it runs best at idle(about 1&1/4-1&1/2 turns out), needle set to the middle, stock header, and a Q4 pipe.

When I had it jetted too lean it was hard starting hot. When I had it jetted too fat, it was hard to start hot. Today I settled on a 132.5 main and it goes great at WOT. I think with the old CV carb it was doing the same thing from stock to modded with a Dynajet kit. Today I changed the plug to the hotter NGK CR7E gaped to .030 as a "Hail Mary" try and it runs fine but it still is hard starting when hot. I have to pump he throttle to get it to fire then pump it to get it to fire up. Then it'll go to idle. Here's the messed up part, when I put it in 2nd gear and bump start it, she comes right to life the first time it goes through a compression stroke without giving it much if any throttle at all. I don't get it. Any ideas?

 

How does this auto decompression gadget work? Can it be removed or adjusted?

 

Have you checked to see if your valves are out of adjustment?

 

I was going to do that today but I got busy with other things. Tomorrow I'll do that. What's the clearances supposed to be? I need to bring home my feeler gauges from work.

 

Yeah, the exhaust valves are really close to the bottom of the tolerance. I'll pull the shims when I get time and take them to work to shorten them in the surface grinder. I'll take them right to the high side of the tolerance so I won't need to worry about it for a while.

 

FD I have one valve that is near the low limit, I thought about thining the shim down with the surface grinder too. I googled grinding shims and found that the shims are likely only case hardened, so as you grind you will take off hardened material and expose soft material. I wouldn't think a few thou would matter, you would still have hard material on the surface, but I decided for the ~$7 a new shim costs, I would just buy new for peace of mind. Let us know if you do grind them I'm still tempted.
Dan

 

If that's the case, then I can do the side that's not in contact with the cam lobe. I doubt they're just case hardened, little dinky part like that.

 

Dan, you tightwad!

I think you're right on a material treatment on the shims. Even though there's not a direct contact on the shim by the cam or such, that's an awfully critical point of clearance. In a valve train, I can't see cheaping out.

 

I have a friend with a KTM that had the same problem. Wouldn't start hot but idled and ran fine once it did start. The problem was the plug cap. The connection between the wire and the cap. He cut off about 1/2 inch and re-screwed the cap back on the wire making sure the cap spike was in the middle of the copper core in the wire. Problem solved. Good luck.

 

I'll do that too. Thanks for the info! It might be one thing and it might be a combination of 10 things. That's one less thing it could be.