I hate it when they do this.

[mogollonmonster]

If I didn't know any better, it sounds like a vapor lock issue, which is really odd, especially in the winter.

It always concerns me when a knowledgeable person like you has problems with trouble shooting. I'm sure you'll figure it out, and likely it'll be something so silly as to be stupid.

Passing thought, have you checked the pick up tube for a burr? My buddy Scotty and I had a similar issue with a parts box build we did recently, the tube had been tightened with pliers which had obviously slipped. The float would catch at the top instead of sinking.

 

[crassius]

I think I found it yesterday, but not sure yet till weather and workload cooperate for testing.

Looked at mag and had a lot of oil in there. For last 2 or 3 years, factories have been drilling the mag mount holes right through into the inside of the case, so that the flat side of the armature is all that seals those holes. In cases where the armature is a bit crooked and hits the case at other points, I've had to put 4 thin washers between armature and case so that all 4 screws will seal.

I pulled mag off & fitted a new one and think that may work now, but didn't look closely at old mag. Later, I noticed that the 4 rivets had never be seated into the armature, leaving needle sharp points on the case side and smooth rods out the front. There were some burn marks around the rivet that ground was soldered to and around some of the points. I'm thinking the return path of spark was arcing there and got hot enough for the ground to fail.

I put about 8 or 10 tons on those rivets and resoldered ground wire. Now all is straight and flat, so I'm thinking it will be OK when I get it back into the bike.

The mystery came from the fact that the meter didn't push enough voltage to cause the arc, so always read just right when testing. I'll post again if it fails.

 

[Kartooo]

been following this along since the start.
you know i been rebuilding auto transmissions for over 40yrs now to earn my daily bread.
no wires, none , 0 in the begining. now there are fistfulls.
i have come to the conclusion that electricity sucks !!
i 'm sure you agree with my last statement.
sounds like you found your solution.

 

[crassius]

got some time today - I hog out sprockets to fit over hub caps on coaster wheels for $8 and have a guy that builds cheap coaster bikes that I do sprockets for, he has 6 here to do, but called and said he won't need them till next week after all

so, with weather not bad today I put all original parts back on problem bike and everything seems to work now - will need to ride more to be sure the repaired mag will stay healthy, but I think it's done

 

[xXNightRiderXx]

Sounds like a heat issue. Some engines, when they overheat, shut off because the heat thins out the air, so you get less. That explains it running fine after a minute. It also explains the sputter before it quits, and explains the lack of a visible reason. They should have coolers for these engines, but if not, make one. Sorry, thought I was at the end of the thread on the first page. Still, if that wasn't the case, try a cooling method.

 

[crassius]

as mentioned, it is good now - problem was due to heating caused by arc internal to armature plates