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WALKINGWOUNDED

NO START CRF 450 UPDATE

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You may no from previous posts, I am trying to fix a no spark condition.

The alternator called for 9-25 ohms, it had 15 ohms.

The pulse generator called for 180-280 ohms, it had 238 ohms.

The ignition coil primary called for .1-.3 ohms, it had 0 ohms.

The ignition coil secondary called for 9-16 ohms, it had 0 ohms.

I found that rather strange. I was expecting too high or too low of resistance, but o?

My 125 runs so I checked the ignition coil and it had 0 ohms on both sides of the coil also. One note though, each time I connected the leads of the meter to either one of the ignition coils, the meter would breifly show a reading then go to 0.

I think its official, I have no idea what I'm doing. I will check some more tomorrow and post again.

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MONTY SALYER #045

REESE SALYER #746 AKA CHICKEN LIPS

Beaumont,Texas (mosquito coast)

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Hi, when you check more again, check also that your meter is in the right scale. Usually the digital meters just blink something and then shows zero if value is out of the scale range

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Guest gcouture

Is this a rebuilt stator? If so, reverse the wiring of the pulse generator or stator and try it again. In my case, I had soldered the connections backwards. Also, Check continuity up to your CDI box with your meter. You may have a broken wire. Check your secondary coil output with the plug cap. You should see abut 11K.

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Hi gcouture,

Actually all this information is refering to the ignition coil mounted in front and above the cylinder head. The stator set has not been touched. Also I'm not ruling out a wiring problem yet, but when I push start it, it runs fine all day long. Generally with a broken wire you have open circuit and it wont start even when its pushed.

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Hi gcouture,

Actually all this information is refering to the ignition coil mounted in front and above the cylinder head. The stator set has not been touched. Also I'm not ruling out a wiring problem yet, but when I push start it, it runs fine all day long. Generally with a broken wire you have open circuit and it wont start even when its pushed.

If you can push start the bike and it runs, but kick it and it wont it might not be electrical at all.

I hate to ask this, but have you checked the valve clearance?

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I second ShawnMC. You started saying "no spark condition" but than if you push start it than is definately not an electrical problem.

After push start, does it idle fine? if yes, definately check your valve clearance!

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I read somewhere...? :cry: maybe here, maybe a mag... that there is a fragile connection on the stator that likes to break off for no reason.

Anyone else read this?.. I remember no other details besides check it an fix it if it looks cracked.

I'm really no help. :cry:

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Thanks classic, I'm not going to rule that out, but I did an ohms check on the alternator and the exciter windings and they passed. I would think if there was poor connection or open circuit, it would have shown up in that test. At this point I aint ruling out a scratched fender causing this problem. Thanks and I'll post as diagnose. :cry:

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Hi Shawn-mc,

Yes I did adjust the valves, I am aware of the valve problems. I replaced the intake valves and piston about a year ago even though everything looked fine. Sometimes it will kick start a few times in row, then it wont kick start for ever. It will push start everytime. Im thinking that even with a valve/compression problem, I should still have spark and I dont. I did a compression check after the valve adjustment and it had 75psi while kickin it over. That is with the decompression arm activating the exhaust valves. I'm not sure what the specs are but I still come back to no spark. I will post as I diagnose. Thanks

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I have an update. We have 6 bikes and I can see the spark on all of them except the 450. As stated in an earlier post I even held the spark plug and no jitter bug across the shop. Both mags ohmed to specs. I reset my ohm meter and the ignition coil passed primary and secondary test.

I was just out in the shop kicking like a mad man when I pushed on the kill switch and presto there was blue spark. So I unplugged the kill switch again and still no spark. I reconnected the kill switch and what I finnaly figured was I have to push the kill switch each time I kick it and it will produce spark. If you hold the kill switch down while kicking, no spark. I have to push it each time I kick it to make it spark. I even disconnected the green wire from the coil and still no spark. What does this mean, I have no idea but I'm gonna open up the harness and/or borrow a cdi unit from a freind. I will keep everyone posted "as the stomach turns". :cry:

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Sounds like your kill switch is grounding out. Disconnect it completely or replace it. They do go bad.

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I sounds like the coil is open somehow and when you ground it with the kill button, its finally firing across the way it should.

If replacing the kill button doesnt work, try a new coil. and check all your wires for bare spots. somethings not right in little tokyo... :cry:

but that kill button deal narrows your issue way down. Its not the stator or the box....

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Yes Shawn-Mc, just like on car you can "scratch ground" across the terminal and load up the windings and presto, spark. I think thats what I am doing with the kill switch.

I am going to the track in the morning and one of my thumper friends is going to let me try the cdi box. Its a quick easy test. I will update after that.

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Hey I know this is a VERY old thread but I have the same kind of problem as you guys were describing with a spark only after pressing the kill switch. I bought my 2007 crf450r with a blown head gasket and we weren’t able to start it when I bought it. I swapped the cdi into our ‘05 250r and it fired right up so I know it’s good and the ohm readings all were within spec for the ignition coil, spark plug wire, stator and pickup coil. I’m wondering if I did something to the stator when I was messing around trying to get the timing chain lined up or what you guys mean by a “scratch ground”

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16 hours ago, Austin Freeman said:

Hey I know this is a VERY old thread but I have the same kind of problem as you guys were describing with a spark only after pressing the kill switch. I bought my 2007 crf450r with a blown head gasket and we weren’t able to start it when I bought it. I swapped the cdi into our ‘05 250r and it fired right up so I know it’s good and the ohm readings all were within spec for the ignition coil, spark plug wire, stator and pickup coil. I’m wondering if I did something to the stator when I was messing around trying to get the timing chain lined up or what you guys mean by a “scratch ground”

Go through all the connections at the coil itself. Ultimately I believe that was the issue with the original poster, too. Make sure the ground at the coil is clean and making connection. Clean the positive connection and maybe put the pliers on the female connection from the harness so it bites the tab a little better. Don't rule out a bad connection between the wire terminal and the damn wire itself. It's annoying to find, but I've found it more than once. Found a wire broken internally, within the insulation once, too. It was a "winning the lotto" kind of thing, but it happens.

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38 minutes ago, Shawn_Mc said:

Go through all the connections at the coil itself. Ultimately I believe that was the issue with the original poster, too. Make sure the ground at the coil is clean and making connection. Clean the positive connection and maybe put the pliers on the female connection from the harness so it bites the tab a little better. Don't rule out a bad connection between the wire terminal and the damn wire itself. It's annoying to find, but I've found it more than once. Found a wire broken internally, within the insulation once, too. It was a "winning the lotto" kind of thing, but it happens.

Alright I’ll have to tear into it again today and see what I can find. Thanks for responding to such an old thread!!

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Little update: I took off the left side case cover today and found a few metal burrs stuck to the pulse generator so I think that might have been my problem. I also found my plastic oil pump gear in pieces at the bottom of the case and the oil pump doesn’t spin freely. It does spin with a LOT of resistance when I use pliers, so I guess that means I’ve got to split the cases whenever I get time and address that issue 🙃

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14 minutes ago, Austin Freeman said:

Little update: I took off the left side case cover today and found a few metal burrs stuck to the pulse generator so I think that might have been my problem. I also found my plastic oil pump gear in pieces at the bottom of the case and the oil pump doesn’t spin freely. It does spin with a LOT of resistance when I use pliers, so I guess that means I’ve got to split the cases whenever I get time and address that issue 🙃

Ya, that oil pump should spin effortlessly. Clean out the pick up, but figure out where the debris is coming from. My bet is the left side main bearing race on the crank or the cage that separates the rollers on the left side. But the cases definitely need to come apart.

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