2006 crf250 starting problem. HELP!!!

Starting on these is all about having proper valve clearance and then having the right combination of pilot jet and fuel screw adjustment. Get all these right and they start very easy.

The symptoms you describe, doesn't kick start, will pull-start, and will kick start when hot, usually point to loss of valve clearance. But you say the valves have been shimmed. I say re-check the clearance. It is easy to do and only takes a few minutes.

Let's assume you check the valves and they are fine. That leaves your pilot jet and fuel screw. Your symptoms sound like you might be lean on the pilot/screw combo based on the fact that it doesn't want to start when cold and will start without the hotstart when hot. Therefore, remove the pilot jet and fuel screw (be careful of the small spring, washer, and o-ring) and blow the passages out well with carb cleaner. Then reinstall and set the fuel screw to the stock setting as a starting point.

If all this doesn't work, it might be time for a valve overhaul.

Even if the valves have been shimmed the valves may be leaking at the seat. Sounds like time for a valve job.

Paw Paw is correct, money back guarantee your intake valves and valve seats are shot.

Do the simple things first. Like FGR said, check your jetting first to make sure your not too lean or the jets are plugged and causing lean symptoms. If that checks out ok then move on to the valves.

When the valves wear out the clearance becomes tight as they pull up into the head. That happens as the sealing surface of the valve becomes concaved from the wear. A this point the valves can be adjusted back into spec like what may have happened with your bike, but with a bad valve face they will no longer seal adequately. Running like this will also round the sealing surface of the valve seats requiring a valve job to get the seats back within acceptable margins.

To check the valve condition you'll have to either preform a leak down test of tear the head apart and visually inspect them. Your problem could be coming from the carburetor, but being an '06 CRF it is also very likely the valve issue. Hopefully it's the former not the latter!

Check the jetting first, 42-45 pilot should be good, anything smaller may be too lean. Check the fuel mixture screw on the bottom of the carb, between 1.5-2.25 turns out. Main jet between 170-178

If the bike sat for any period of time the pilot jet can become gummed up, check to see if it's clean and not plugged up. Also check that the accelerator pump shoots a strong stream of fuel when you turn the throttle. When the pilot starts to get gummed up the bike will backfire and pop when you let off the throttle.

I hope you find a carb issue because that's easier/cheaper to fix. Knowing the history of the CRF 250's and hearing your same story countless times from customers, I have a strong feeling that you need new valves. I hope I'm wrong about that, good luck!

I feel like the correct intake valve clearance should be .006" and the correct exhaust clearance should be .011". With the fact you had just had the valves re - shimed, I feel like you need valves. Do a leak test to be sure.

Paw Paw

I'm not real familiar with Honda's, except for the numbers of head and valves jobs one of our sponsors did on them, but my guess is that it's the decompression mechanism you are talking about. Nothing is supposed to clank. Your description of the problem is classic for those bikes. I can't remember the times people were push starting them, or pulling them with another bike to start them before a race. Even older slow guys at our track that rode for fun were replacing valves and or heads on those things. Unfortunately, I think you may be in for more than you bargained for.

I don't how else to say it as it has been said several time in this post, but....

You need a valve job!!!!!!!!!!!!!!!!

The decompression mechanism is on the camshaft. It usually consists of a weighted lever and a spring. It opens an exhaust valve when you jump on the kicker, so it's easier to kick over. It's always in this position when the motor is not running. Once the motor starts, the centrifugal force of the cam spinning disables it so the valves can work normally. It's a pretty simple mechanism.

Shimming the valves and a valve job are not the same thing.

Paw Paw

Good move. You didn't say what the CRF cost you, but shimming the valves won't do anything. The seats in the head are shot, and need to be reground. Trading it is the best thing you could have done. You can freshen up that bike for nothing compared to the CRF. Congratulations.