Full Throttle

[K2kendrick]

I have a 2000 YZ250 I just had the top end done, bottom end done, power valve, reeds. When I put it back together and started it, it would not idle, and just kept reving higher and higher. It will not idle at all, and every time I kick it over, it starts going full throttle. I checked the carburator, and all of the parts seem to be working fine. I have to hit the kill switch right after I start it, or it will keep climbing. What would do this? How do I fix it?
thanks

 

[Y2Z]

did u turn the idle screw in more? u might have moved it while taking your bike apart...

 

[Moteaux]

What about the throttle cable routing?  It's not routed differently or anything that would make it hang the slide open?

 

 

[K2kendrick]

No the Pilot air screw, is set to the factor specs. The bike was running fine, as far as the carburator goes until the top end blew. I had that replaced as well as the bottom end. I took the motor home put it in the bike, and when I cranked it, it was just wide open. I still could turn the throttle, that is what flooded it out the first time, after the kill switch would not work.

 

[Studboy]

I'll bet that the slide was installed incorrectly, or the cable is routed wrong. Check for freeplay in the cable.
Otherwise, you probably have an air leak.
(The idle screw IS turned out, right? :) )

 

[K2kendrick]

The pilot air screw is one turn out per the factory specs. as far as slack in the cable I havnt found any. The slide is working properly. I have taken it to the shop, and they have looked over the carburator, and said that it is working fine. As far as an air leak, I dont know were I could get one that would make it do that. Would the Timing have anything to do with it? How about the Power valve? It has new reeds, and a new air filter. How about the TPS would that have anything to do with it?

 

[jboomer]

idle screw, idle screw, idle screw, idle screw, idle screw, idle screw........keep saying idle screw!!!!! They're not telling you to check the "pilot air screw." You have an air screw and an idle screw. Check to ensure the idle screw is out, not tightened all the way in. I think it has something to do with something binding within the carb too. Either the cable is routed wrong, causing it to remain stretched, or the slide is hung up within the carb (maybe the needle is caught in the return spring or something). The air leak also sounds like a viable culprit. Maybe the base gasket or reed gasket was torn or misplaced when it was put on the bike. The only way to check this (since you obviously can't let the bike run long enough to spray WD40 around the engine) would be to have a leak down test done. I doubt the Powervalve has anything to do with or the timing.

 

[K2kendrick]

I turned the idle screw out and it calmed it down alittle, as soon as you touch the throttle though, it starts to climb and doesnt stop. I have turned the idle screw out a long ways, and it starts to idle, but doesnt last long. I will have to check on a leak down test.