05 RMZ250 No Start - Help!

[bkoz]

I am trying to get a 05 RMZ250 to start. The bike will fire and run for a couple or revolutions then it dies. To get it to fire I have to crack the throttle numerous times. So far I have checked the following:

Compression cold - 55 psi

Leak down test - 97%

Valve clearance - in spec, a little loose on the exhaust valve the decompression lever works on

Decompression lever - replaced

Spark plug is new, I have tried a couple different ones at this point

Ignition coil - primary coil resistance is right on the money, the secondary is giving a measure of 13 kohms, manual wants 10 kohms, I don't think this is an issue as I am getting a good spark and the bike does fire.

Fuel is fresh.

Carb - stripped it down and checked orifices and jets for clogging, it looked very clean. You can see the accelerator pump working correctly.

I am stumped and at a dead end, help!

[bkoz]

With the idle cranked right up the bike will start and I can keep it running, poorly, with the the throttle. Slipped flywheel maybe? Ideas?

[Sipe3]

I'm stumped with you. I know that is not what you want to hear tho. Please post the fix when you figure it out, I am curious. Sorry, I couldn't be of any help.

[gscx]

The 04 rmz/kxfs had CDI issues. I am not sure if it carried over the the 05s though. If you know someone with the same bike then see if you can get thier CDI. And have you checked to see if the plate on the throttle slide is installed correctly?

[bkoz]

The 04 rmz/kxfs had CDI issues. I am not sure if it carried over the the 05s though. If you know someone with the same bike then see if you can get thier CDI. And have you checked to see if the plate on the throttle slide is installed correctly?

What am I looking for as far as the throttle side plate? I have had the slide out and the plate oring looks ok. The plate is clipped into the slide and the slide moves smoothly. Also the bike just died out of no where and the carb had not been apart anytime before recently. Now that you say CDI that maybe a possibility also. The bike was started and idling to warm it up when it died and would not restart.

[gscx]

well since it just started doing it the plate wouldnt be an issue, but the cutout has to be on the bottom for furture reference. Have you checked your timing?

[RideKx250f]

check the timing?

[bkoz]

well since it just started doing it the plate wouldnt be an issue, but the cutout has to be on the bottom for furture reference. Have you checked your timing?

Valve timing is good. I don't know how to check ignition timing without the bike running. I have not yet pulled the flywheel to see if it has spun on the crank but with the valve timing being good I don't think this is an issue.

[gscx]

The only thing i can think of is a bad CDI or maybe the woodruff key is sheared. But i dont really think that would happen, you dont know anyone with a 04 to 06 rmz250 or 04 to 05 kx250f?

[dragracer1107]

try slightly bending the proms that are at the cdi connection, I had the same probleme with my 06 kx250f, i bought it and the guy told me the cdi was out, it would start, but died soon after, after messing with it for a while I discovered the cdi connection was loose, I bent the proms slightly and probleme solved. you might give it a try. sometimes it would not run at all, sometimes it would just miss like it was on the revlimiter all the time.

[mx875]

Not sure if you recently replaced the piston, but if you did, the same problem would occur if you didn't break the engine in properly. It would run great with full power for about two laps around a motocross track, until the piston rings heat up and warp. The bike stalls, then restarts but runs really poorly.

[Caress]

check if your cam chain slipped, sometimes it can slip a tooth over on the sprocket which would make it run horribly. your cams could have ceased up, but that should make a terrible noise when you start it

[bkoz]

I eventually gave up on this bike and gave it back to the owner. He brought it to a shop and they replaced the piston, cam chain and rebuilt the head only to find the HOT START WAS PARTIALLY SEIZED OPEN. The worst part is all those parts were just recently replaced. Oh well. At least he is riding again.

[downonmonday]

I eventually gave up on this bike and gave it back to the owner. He brought it to a shop and they replaced the piston, cam chain and rebuilt the head only to find the HOT START WAS PARTIALLY SEIZED OPEN. The worst part is all those parts were just recently replaced. Oh well. At least he is riding again.

Now that is an expensive way to troubleshoot.

[bkoz]

I was just talking to the owner again. He said they also installed a used carb. I would guess that was when the hot start was found!

Now that is an expensive way to troubleshoot.