Karting??..
I should have clarified, the 14.5 was the lap time lol I think our highest hp engine was like 13 and a quarter. Pretty decent for a 5hp Briggs. I'm all ears lol
LOL ok. no secret now...
It started out while deep sea fishing. There was a collage student on board who was studying to be an engineer. (I wished I could have went this route, so I was interested in what he had to say..)
Through our conversation he mentioned that they were studying magnetic fields and were using a 5 HORSE BRIGGS in their study. My ears got pointy like Dr. Spock in Star Trek.
As you know, there was a lot of Juju about what the optimum coil gap was to run, and what gap to run for low end and for top end..
Their study concluded, that a percentage of magnetic energy was absorbed by the first leg to pass over the coil during rotation would get sucked back into the cast iron flywheel BEFORE the second leg of the coil would break magnetism that would cause the spark energy to release!
So they concluded as much as 38% of potential spark energy was being lost back into the cast iron.
Boy, did that get my wheels turning. I COULDN'T WAIT TO GET HOME.
This is just the problem I was hoping to solve... heavy azz flywheel, when the light ones were getting impossible to find, and the spark issue to boot !
So here's what I did.. I knocked the retaining roll pins out of the magnet and removed the magnet. I chucked the flywheel into the lathe (with old cut off crank) and turned down the OD of the flywheel .020 deep or .040 off of the OD total. No rule on flywheel diameter, just weight and 'no machining'. I figured, how could anyone prove who machined the flywheel?
Not only is the weight of the flywheel reduced, at the heaviest part - the OD, but the coil would also be further away from the cast iron!!! AND you could get that coil right next to the magnet for best spark !!
I would weight the flywheel with the magnet, of coarse, and if the flywheel was still way over the minimum, I would then re-chuck it it in the lathe and shorten the fins until it was at 6 lbs.
The only thing I had left to do, was to leave it outside so that the dew would rust up the fresh machine marks. Unless you were looking at the OD, you could not tell anything was ever done. Got good at it too. I could almost perfectly replicate the factory machine trail. LOL
Boy, stuff like this, really made it fun !!
