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2004 CRF250X Starts yesterday, not today

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I recently purchased a clean, low mileage 2004 CRF250X. Completed a thorough service: Valve check (intakes .005 and .006; exhausts .011 and .010), complete carb cleaning and sea level jetting check (42pilot, 145 main, PAS 2 1/2 turns). Stock muffler with 1/2 hole drilled in diffuser. Twinair filter with top of air box opened up a bit. New battery cranks over engine strongly.

The issue: I can never be sure if the bike will start!

After first riding the bike only 3 miles it died.

I replaced the coil/plug cap because I thought the original tested bad (with an ohmeter)...not sure the new one was any better...but the bike started and ran fine for 2 days (220 miles) at the NH Trail ride in June. Thought all was fine...

Since then...sometimes it starts and sometimes it doesn't.

Just did another complete carb cleaning...bike started immediately...so I reaasembled tank, seat, etc...now no start...not even a burble. It seems to me like no spark...

2 questions: May I assume that when you remove the plug, connect it to the coil/cap, lay it across the frame (to ground it) and then crank the starter...you should SEE a visible spark jump the electrode, correct?

Second, do these bikes have a history (or tendency...) to have a common ignition failure point? Such as the pulse coils on older generation XR600's or something like that...

Any advice is appreciated...yes I do have the factory manual...however some of the ignition system tests need more then a digital multi-meter.

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You've probably already thought of this, but since it's intermittent I'd inspect every single electrical connection on the bike, especially grounds.

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Check your valve clearance. I know you said it was checked when you got it. But its also an 04 and if its never had valves put in it its waaay overdue. And yes they can go bad just that quick. One day it will run perfect and the next zero clearance on the intake.

Check your clearance. Its not hard. Its all in the owners manual. All you need is some basic hand tools and some feeler guages.

If they are at Zero clearance (you cant get the smallest fealer guage in there) dont bother shiming them they are done. You will need new valves.

This is always the 1st thing to check when its starting hard.

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If the previous owner shimmed the valves just prior to the sale (shady), it is quite the common thing for it to only last a few hrs before rezeroing. Once the hardened coating is gone the bare Ti wears away rapidly. I would check the valves again just for piece of mind. But as you describe it as intermittent it seems like it will probably be electrical related. Afrayed wire could be grounding out in some out of the way place. Batt cables clean? any burnt connectors? Loose grounds? I remember one guy found the kill switch wires bare behind the headlight.

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hi check the insulation on the two wires that go into the connector that plugs into the coil,as ive just had loads of trouble starting mine and it turned out that a tiny bit of insulation was missing right at the bottom of each wire which caused a weak spark,changed the wires and it now runs and starts sweet:thumbsup:

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Thanks to all for the advice...here's an update...

Went to work checking wire harness connections.

Seems that the 2 wires that insert into the white plastic connector that snaps onto the coil/plug cap may have worked themselves "out" a bit. I pressed them back tight with a fine blade screwdriver.

I'll answer my own question from above: With a non-functioning ignition system, you WILLNOT see an actual spark jump the plug electrodes. I saw nothing until I tightened these plug cap connections...then presto...a nice visable spark. The bike now fires right up...however it did so off and on before. So I'll wait a few weeks...and many starting attempts until I call it "fixed". But I am cautiously optimistic...

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those connectors shouldnt just release themselves, they have 2 locking mechanisms in the connector, did you happen to see if they were loose? Or were you talking about the pins fitting loose on each other...

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But its also an 04 and if its never had valves put in it its waaay overdue.

I have an '04 with 3 original valves, but one intake has 1 year on it. 4.5 years......

I blew up the crank last week though, because I tipped it upside down and oil ran out of the breather and soaked the filter, so I did not really know how much came out. And I did not check the oil level, then I pinned it for 9 miles on the freeway. Yes my mistake.

Upon rebuild I asked the mechanic to check the valves and he said they were all fine. he said the cylinder was fine too but I ignored that advice and changed it to an Athena :):D

Anyway, if the filter has been installed correct the valves CAN last a long time especially if it's not run against the rev limiter all day. Mine is trailridden, usually short-shifted, and I'm going thru brake pads and tires (and now crankshafts) quicker than valves.

You 'd be surprised how hard it is to get the filter seated, and if it is NOT seated, and you ride it in dust, you will ruin your R-Intake valve then you'll be a postin!

Tom

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