42A707 motor 18.5 HP no spark

[Tinkerer200]

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

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

 

[bertsmobile1]

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

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.

 

[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.

 

[HiTekRedNeck]

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

yep, shes turning over with a jumper box attached.

 

[HiTekRedNeck]

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.

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.

 

[HiTekRedNeck]

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.

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

 

[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

 

[Luffydog]

Glad to be a help to ya.

 

[Darryl G]

Physics has nothing to do with electricity bert.

Wrong, but glad to hear you got your issue resolved.