Author Topic: Fuel, compression, strong spark, no fire. HELP!  (Read 3627 times)

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gixxer6

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Fuel, compression, strong spark, no fire. HELP!
« on: February 08, 2018, 05:04:59 PM »
It’s a new motor, so I set the timing right on the timing mark.  Great compression, I spray starting fluid directly into the carbs, STRONG blue spark.  But it won’t fire.  It won’t even try to fire.  It acts like there is no spark at all.  I tried another CDI with the same results.  The motor is ported, so I tried turning the stator a little clockwise, still nothing.  I turned it more, you guessed it, nothing!  I’m stumped!  Any ideas? 

rminier

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #1 on: February 08, 2018, 05:35:49 PM »
 Wow....only thing I can think of is timing way off.
Could you have knocked the flywheel key out of position when installing flywheel...and it's several degrees off? Probably not since you have moved the stator around.
Do you have a 12 V automotive timing light?
Do a quick, simple check.....find close to TDC on the MAG side with a screwdriver down through the spark plug hole....you can get extremely close without messing around with a dial indicator.
With the MAG piston at TDC, observe the very top of the drive clutch, then rotate the drive clutch backwards about 10 degrees and mark the very top of the clutch. Yank the recoil and see if it is sparking anywhere near that vicinity with that mark at the top of the clutch.
« Last Edit: February 08, 2018, 05:50:03 PM by rminier »
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Vader440

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #2 on: February 08, 2018, 07:30:30 PM »
Probably have done all off this, but I'll throw them out there anyway. How are you checking for spark, a tester or the actual plugs your screwing into the heads? I've seen plugs that would spark outside, grounded to the head, but as soon as I'd screw them into the head they would die. I'm still baffled by that but it happened. What are you using as starting fluid? My small engine teacher told us years ago, if you have compression, ignition and carburation it has to run...................unless it's out of time. It'll be interesting to see what this turns out to be.

gixxer6

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #3 on: February 08, 2018, 07:59:26 PM »
Bad stator.  Pulser coil is open. 

mswyka

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #4 on: February 08, 2018, 08:03:17 PM »
Before going to the work of pulling the stator, if you can, swap in a new spark coil.  We have had several spark coils go bad to the point where they would spark the  plugs out of the engine but not fire under compression.  In those instances, with a new spark coil and we were on our way.
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Interceptor123

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #5 on: February 09, 2018, 12:43:30 AM »
I had the same thing happen 2 years ago on my invader. Turned out that even though I was sure I had the stator plate in the right spot it was about an 1/8 inch off when I pulled the flywheel.

Boomologist

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #6 on: February 09, 2018, 05:04:38 AM »
Could very well be plugs or anything else in the high voltage side of the system. As with plugs they can fire just fine in air but under compression there is greater resistance to spark making it across the gap. Same is true with the rest of the high voltage. If any part is weak it may not jump the gap under the added resistance of compression.

gixxer6

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #7 on: February 09, 2018, 08:11:31 AM »
I measured the resistance of the pulser coil.  It measures open (open = bad, my spare stator measures around 25 ohms), so while I may have other issues I will need to change the stator regardless.  It won't be so bad, I already have the recoil off and stuff removed to get to the wire connections, so it's just a matter of removing the flywheel and swapping it out. 

Thanks for the replies! 
« Last Edit: February 09, 2018, 08:15:17 AM by gixxer6 »

rickbmac

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #8 on: February 09, 2018, 09:20:37 AM »
Is 25ohms within specs?  I only ask because I do not know and am sure this will present its ugly head in the future.

gixxer6

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #9 on: February 09, 2018, 09:46:31 AM »
FSM states: "23 Ohms +/-20%"

kawhead

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Re: Fuel, compression, strong spark, no fire. HELP!
« Reply #10 on: February 09, 2018, 09:50:54 AM »
you found your problem, 25 ohm is correct