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What has spark, fuel and won't run?

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What has spark, fuel, compression and won't run? My bike of course.

Stock S motor and carb (2003 KLX400SR).

I did something your Dad always told you not to do, and that was "don't fix something that isn't broken!".

My bike has 23,000 miles on it and I'm planning a trip to Colorado in about 45 days so I replaced the stator even though the original was still working. I had heard of the limited lifespan of the DRZ stator (depending on treatment of course), and since I don't know how my bike was treated for the first 10,000 miles of its life I decided to change it out so I didn't have a failure during my trip.

Anyway. I replaced the stator (with a quality aftermarket) without any problems, started and ran the bike, put it to bed for the night. The next day riding to work the bike started hesitating at around 60 mph (6500 rpms), then I couldn't even maintain 60 mph, then it hesitated and got slower, I couldn't go 50 or even 40 mph, It just seemed like it wouldn't take any load (I pulled in the clutch and free revved it a couple times without a problem), finally the bike died.

When I got it home I called the stator manufacturer and using them and my shop manual I checked for the correct resistance across the two plugs, checked and made sure nothing was shorted to ground, all seemed to test OK. I have spark, so while I was immediately thinking the stator was bad now I was now thinking it was not. So I took the carb out and cleaned it (no evidence of crud in there) and the bike still won't start.

What else should I check before putting the stock stator back in the bike and trying that?

[EDIT] And before someone asks, yes the vacuum line is connected the petcock. My actual tests have been with the petcock in the prime position (and it flows well when directing fuel into a catch bowl). [EDIT]

Thanks

-mtnpat

Edited by mtnpat

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Did you test the plug wire? My RM would not run but had spark and I found that the boot made contact out of the cylinder but when in, it wasn't. Something simple to test.

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Another test you should do is meter from black wire and white wire of the signal coil (plug at CDI) to each of the yellow stator wires (plug below R/R). Try all combinations. Any reading is bad, the meter should say OL (open line) the whole time.

A quick test is also try to start it with the stator charge circuit (3 yellow wires) unplugged. Not as sure as metering though.

Any thing else you have done recently? Valve clearance?

Is the plug wet? Have you tried another plug (cheap, easy)

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Another test you should do is meter from black wire and white wire of the signal coil (plug at CDI) to each of the yellow stator wires (plug below R/R). Try all combinations. Any reading is bad, the meter should say OL (open line) the whole time.

Yep, checked that.

Is the plug wet?

Not sure, I definitely need to check that.

Have you tried another plug (cheap, easy)

Yes

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Did you test the plug wire? My RM would not run but had spark and I found that the boot made contact out of the cylinder but when in, it wasn't. Something simple to test.

No, how do I do that?

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No, how do I do that?

Examine it closely. You are looking for any cracks in the rubber that could let it arc when in the head. You are looking for any sign of damage to the wire and any sign that the connector that clicks over the plug has been broken from the wire.

Generally the answer to your question of "what has fuel, spark, but won't run" is 'a drz with spark at the wrong time from a faulty stator'.

If the valves are down to no clearance you could have a bike that will only start if you push start it down a hill. If the valves are ok but it will only start down a hill then that can also be a weak stator. The extra engine rotational speed and not having the draw of the starter on the battery will help start in both these situations.

Since not everyone seems to know.......... Push start (aka bomb start, aka coast start) means getting the bike rolling down a hill, putting it in gear and letting the clutch out so the momentum of the bike starts rotating the engine. You often have to do it in 2nd (or even 3rd)so the rear tire does not lock up, but you need to be coasting a bit faster. Obviously refrain from doing this if there was bad mechanical noises when it quit or you suspect mechanical failure.

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What resistance did you measure on the black wire to white wire on the 4 wire connector? How did you do it? I ask because the resistance spec is so small that it usually requires taking a 'leads touching' resistance, then the signal coil resistance, and subtracting the 'touching' reading from the 'measured' to get 'result'.

(measured resistance) - (reading with leads touching) = actual resistance

Scale must be ohms, not kohms or Mohms.

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http://www.thumpertalk.com/forum/showthread.php?t=977565&highlight=wires

http://www.thumpertalk.com/forum/showthread.php?t=965771&highlight=wires

Either of those links help?

and I can't find the link but another user had the experience of installing new stator and having the misfortune that the flywheel rubbed on the wiring and wore through it. It is probably worth your time to pull the stator off and inspect.

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If the valves are down to no clearance you could have a bike that will only start if you push start it down a hill. If the valves are ok but it will only start down a hill then that can also be a weak stator. The extra engine rotational speed and not having the draw of the starter on the battery will help start in both these situations.

Ah, that is why you were asking about recent maintenance such as valve clearance.

I adjusted for the first time about a month ago, had one valve out of spec. Brought all four valves back to the middle of the tolerances (as close as I could). The bike has been running great since valve adjustment. I have a cheap old battery and it cranks like nobody's business (probably not for long though).

Was running great until I replaced stator. I really don't think I messed anything up, it was super easy. Bike ran for about 10 miles then started breaking down on me.

I will inspect plug wire and boot closely as soon as I can get some quality garage time.

Thanks for your help.

-mtnpat

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which valve, how far out, and tight or loose?

Valves get tight as the face of the valve starts to wear. Since there is only a thin hardened layer on the face, once it starts to wear it keeps wearing.

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...Was running great until I replaced stator. I really don't think I messed anything up, it was super easy. Bike ran for about 10 miles then started breaking down on me.

...

-mtnpat

With no other changes, I'd suspect something isn't right with the install or the stator itself. Gotta pull it and see.

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Yup sounds like the stator. If it has all the above but incorrect ignition timing due to bad source coil wiring, which is located on the stator pigtail, it would cause an issue like this. Happened to me. Same description.

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So the bike ran great, then you changed the stator, and now the bike doesn't run great.

This seems like a no brainer, maybe it's the stator......

Why haven't you pulled the side case off to check things out?

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So the bike ran great, then you changed the stator, and now the bike doesn't run great.

This seems like a no brainer, maybe it's the stator......

Why haven't you pulled the side case off to check things out?

Ha ha, I know. Hard to find that bit of quality garage time needed sometimes. Will swap the old one tonight and report back! I can't wait actually........there is that certain feeling of emptiness when your bike is down. :smirk:

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........there is that certain feeling of emptiness when your bike is down. :smirk:

A "beside yourself" feeling...

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mine arced at the top of the plug cable aginst the frame , kill the motor instantly, and my 1979 dr 250 oil injection has the same problem

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