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42A707 motor 18.5 HP no spark

#1

H

HiTekRedNeck

Hello,
I have a hair pulling no spark situation. Motor turns fast enough, so I assume this should be sparking.

1-Replaced magneto, It was a little different but should have worked.
2-pulled flywheel to check stator and wiring
3-unplugged kill wire at magneto still no start
4-checked all grounds and switches, which I believe wont even allow starter to turn if theres a problem.
5-Air gap is .012


#2

B

bertsmobile1

HiTekRedNeck said:
Hello,
I have a hair pulling no spark situation. Motor turns fast enough, so I assume this should be sparking.

1-Replaced magneto, It was a little different but should have worked.
No it won't work, There is a chip in there that controls the spark and very few of them are the same.
2-pulled flywheel to check stator and wiring
Stator has nothing to do with the spark the spark is self generated by the external module. If the 2 are ever connected the coil will have been destroyed.
3-unplugged kill wire at magneto still no start
Should have been the first thing you did. Check the wire to ensure there is never voltage to the coil wires. It is very sensitive even some cheap multi meters can destroy them
4-checked all grounds and switches, which I believe wont even allow starter to turn if theres a problem.
5-Air gap is .012
Click to expand...

good luck


#3

Boudreaux In Eunice La.

Boudreaux In Eunice La.

I agree with Bert The coil may be fried...... Get the right one and try it without the BLACK kill wire hooked up..

Yes checking with a volt meter can do damage ~!~!

Let Us Know Mon Ami ~!~!


#4

T

Tinkerer200

You are mounting the coil correctly, some are not marked which side is up. And if you are getting an after market, and sounds like you are, it may not be good. Plug wires typically exit coil heading towards the back of engine then double back under coil and come out pug - carb side of engine.

Walt Conner


#5

Boudreaux In Eunice La.

Boudreaux In Eunice La.

I'm gonna post one more on here.. Either he got it going or ???

The kill wire spade plug on the COIL always goes down towards the engine block.......


#6

H

HiTekRedNeck

another new coil, new plugs, kill wire off. coil has "this side out" and "cyl side" so I installed accordingly. She wont start on starter spray, and I cant see spark. Damn sure felt it when I decided to hold the plug wire though.
it may be shotgun time


#7

Boudreaux In Eunice La.

Boudreaux In Eunice La.

Try the business card trick to gap the coil...........


#8

H

HiTekRedNeck

Tinkerer200 said:
You are mounting the coil correctly, some are not marked which side is up. And if you are getting an after market, and sounds like you are, it may not be good. Plug wires typically exit coil heading towards the back of engine then double back under coil and come out pug - carb side of engine.

Walt Conner
Click to expand...

new coil installed with wires pointed back, turning back to the front into plugs


#9

H

HiTekRedNeck

It will backfire now, flywheel key still intact. coil ground good


#10

H

HiTekRedNeck

Crazy question, should the flywheel and or magnet be grounded? they both have ground to battery.


#11

T

Tinkerer200

HiTekRedNeck said:
Crazy question, should the flywheel and or magnet be grounded? they both have ground to battery.
Click to expand...

They are fine, not the problem UNLESS the flywheel magnet is weak, not likely. Is the starter spinning the flywheel at a good clip? Some say it takes 600 RPM to fire the CDI coil, I have heard 800. See if it will start with one plug wire disconnected. They will run on one cylinder.

Walt Conner


#12

B

bertsmobile1

HiTekRedNeck said:
Crazy question, should the flywheel and or magnet be grounded? they both have ground to battery.
Click to expand...

Not a crazy question but shows where your mind was during your high school physics classes.
For electricity to move you must have a circuit so everything must be grounded.
Magnets are not electricity and do not care if they are grounded or not, unless they are electro magnets.
Magnetic fields travel through the air regardless of what is around hem, remember all those sheets of white paper with iron filings on one side and a magnet on the other.
About the only thing the mamby pambies will allow school kids to do now days.


#13

L

Luffydog

Check flywheel key might be half sheared if you got good spark might not be firing under compression bad plugs bad fuel or bad compression it self.


#14

H

HiTekRedNeck

Tinkerer200 said:
They are fine, not the problem UNLESS the flywheel magnet is weak, not likely. Is the starter spinning the flywheel at a good clip? Some say it takes 600 RPM to fire the CDI coil, I have heard 800. See if it will start with one plug wire disconnected. They will run on one cylinder.

Walt Conner
Click to expand...

yep, shes turning over with a jumper box attached.


#15

H

HiTekRedNeck

bertsmobile1 said:
Not a crazy question but shows where your mind was during your high school physics classes.
For electricity to move you must have a circuit so everything must be grounded.
Magnets are not electricity and do not care if they are grounded or not, unless they are electro magnets.
Magnetic fields travel through the air regardless of what is around hem, remember all those sheets of white paper with iron filings on one side and a magnet on the other.
About the only thing the mamby pambies will allow school kids to do now days.
Click to expand...

Ironically I'm an ASE certified auto tech in 5 categories, including electronics. Physics has nothing to do with electricity bert. I came here hoping to pick some brains that have maybe run into this exact situation. Hopefully youre not trying to be insulting, but it appears that way.


#16

H

HiTekRedNeck

Luffydog said:
Check flywheel key might be half sheared if you got good spark might not be firing under compression bad plugs bad fuel or bad compression it self.
Click to expand...

Thanks Luff, the key is intact. I'm on the verge of throwing in the towel on this one.


#17

H

HiTekRedNeck

Ended up trying to check compression. Being an auto mechanic, I'm used to seeing a strong spark. Evidently I was getting spark, just couldn't see it or hear it like a car.
One of the cylinders threw a rod. I guess that would cause a no start :laughing:
Thanks for the help though guys


#18

L

Luffydog

Glad to be a help to ya.


#19

D

Darryl G

HiTekRedNeck said:
Physics has nothing to do with electricity bert.
Click to expand...
Wrong, but glad to hear you got your issue resolved.


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