02 CRF450 runs horrible after 4-5 laps

[RickAvery]

Been a member for several yrs, mostely a lurker, reader, searcher & been able to find the answer to the few problems this bike has presented without starting a new thread. I purchased the bike as the 2nd owner in 04. and until the last year, only took it out 10 to 12 times a year mostely trail & sand dunes, with some track. As my son has gotten into MX racing this last year, I've been going to the track with him and loving it. On a recient track outing after ~3 or 4 laps, the bike started to surge and cut out as if it were starving for fuel. (at least that's what I thought). I figured there must be some muck in there somewhere. Took it home and went through the carb. cleaning the ports and jets with IPA and compressed air. Never did remove the slide. Reassembled, installed new spark plug started the bike and noticed the head pipe starting to turn red hot. found the hot start cable was not seated properly. fixed that and she started up fine. High idle with choke on. No idle with it off. Fuel screw set at 2 turns out. took her for a few laps at my house and had good power no back fireing and no cutting out so thought all was fine. Went to the track yesterday and after 4 laps the surging started again. This time I'm thinking electrical. the bike will start but once riding it feels like someone is pushing the kill switch on and off. I'll hold the throttle steady and the bike surges on and off. I tried pulling the choke on during one of these episodes and nothing really changed. the surging continued. I would think if the bike was starving for fuel, pulling the choke on would have changed something in how it ran at least momentarily. Ideas?? Any help would be greatly appreciated.

Thanks

Rick

[tjg53]

It could be that your coil is going bad. I would allso check that bolts on the coil , to see if they are rusty ?

[Shawn_Mc]

You probably have a main crank bearing going bad producing steel debris and its shorting the ignition pulse pick up stator.

What happens is the iron debris collects on the soldier points and shorts when it gets hot/warm.

Considering its an 02 with untold hours on the bottom end, you've got a decision to make. Fix it, or clean the pickup and sell it.

PM me if youre in SoCal Orange County area. I can help ya out.

[shanecarr]

Or the stator, the manual gives you specs for checking them, well worth the 50 bucks. You start guessing at parts and you will spend much more. But Shawn's prolly right.

Edited February 26, 2012 by shanecarr

[Shawn_Mc]

The main problem with checking the resistance on the stator when its cold is it can test perfectly but still be bad. What he'd need to do is test it when its warm. He could pull the stator and pop the cover and all into the oven at 200F for 15 min and then check the resistance. But Id bet its the iron fuzz of death.

[RickAvery]

WOW!!! does that kind of news really have me bummin!!! Thank you all for taking the time to reply. I'm going to perform all of the resistance checks just to make sure all of the related items are OK. If they are fine, I'll then pull the stator/flywheel cover from the bike. What should I be loooking for? are the metal fines something that can be seen? And where should I be looking?

Sent you a PM Shawn.

Thanks again folks!

Rick

[mrmoto35]

WOW!!! does that kind of news really have me bummin!!! Thank you all for taking the time to reply. I'm going to perform all of the resistance checks just to make sure all of the related items are OK. If they are fine, I'll then pull the stator/flywheel cover from the bike. What should I be loooking for? are the metal fines something that can be seen? And where should I be looking?

Sent you a PM Shawn.

Thanks again folks!

Rick

I have an 02 and live in OC as well. I recently replaced my 02 flywheel with an 04 and I replaced ALL of my electric's with 05. I replaced the stator because I wanted it to plug straight into the 05 harness without having to jump the wires. My 02 stator was working fine when I removed it. If you need to test with and/or keep it PM me and we can work something out. Edited February 27, 2012 by mrmoto35

[RickAvery]

Thanks MM35,

Being new to interacting on TT, folks have been very generous & heplful. It's greatly appreciated. I'll check out my stuff and if it's bad, maybe we can make a deal. Thank you for the offer.

Rick

[RickAvery]

OK, I've finally got some time to pull the stator cover off of the bike. Everything looks squeeky clean. No fuzz to be found anywhere. Maybe the bearings are OK afterall? Have some pics but haven't figured out how to upload. Will work on it.

Thanks

Rick

Edited March 9, 2012 by RickAvery

[Shawn_Mc]

OK, I've finally got some time to pull the stator cover off of the bike. Everything looks squeeky clean. No fuzz to be found anywhere. Maybe the bearings are OK afterall? Have some pics but haven't figured out how to upload. Will work on it.

Thanks

Rick

If there isnt a dark grey pastey kinda stuff all over in there, maybe you got lucky and all you need is a new stator. If youve got an ohm meter this is what Id do.

Id turn the oven to 175-200F and warm the stator up and check the resistance. If it runs fine when its cold, you need to duplicate the condition to find the problem. In 4-5 laps the oil should be somewhere between 170-200 degrees and so would the stator. If the resistance changes more than about 10% in either direction you've more than likely found your problem.

Also, is the flywheel stock? If its got an after-market flywheel, some of the heavy ones over drive the ignition and they start to cut out like you've described. They'll work ok for a while, but I think the regulator in the ignition gets to a point where it cant keep up. And instead of turning on and off quickly, they simply stay turned off too long.

[erichshonda]

Check your fuel cap inline breather vent if equiped. I once had a similar problem on my old 03.

[RickAvery]

Didn't think of that. Will do. Thanks.

Rick

[RickAvery]

Well, much has transpired since my bike was giving me the ration of %@^#$. I decided to go ahead and recheck the valves. Oh Holy %^#$%$. The left intake valve was zeroed out and the right one was 0.0015. I mean it went from within spec. to DOA very quickly!! OK, at least I now have a direction to go by. After talking to a good friend of mine, owner of DLR cycleworks in Tx., a go-fast/suspension outfit, I took the head off and brought it to my local moto shop, (not the dealer) with instructions to replace the intake valves, springs & seals. Keep the stock exhaust valves but replace springs & seals, reface all of the seats. I then got onto Fee-bay and picked up a 11.5:1 wiesco piston & Moose gasget kit. The old steed has a new life! She hasn't been this fiesty in years. And idles too!! The total cost for the fresh motor + a few odds and ends was under $600.00. That's a bargin in my book. Thanks again to all who took the time to reply with all of your suggestions, and to Shawn-Mc for taking the time to educate me over the phone. All of your efforts are greatly appreciated!! Happy motoing.

Rick