Mystery Problem...Bad Magneto?

CHIPS X

CHIPS X

New Member
I have a 48cc Starfire kit from Gasbikes.net. I have an intermittent stalling problem. It dies suddenly while running. I've had about ten hours of work installing and diagnosing problems and about a half hour on the bike. I went through the wiring multiple times; no problems with or without a kill switch. I swapped an ignition with a buddy; his ignition works on my bike, my ignition works on his bike. When we switch back mine works intermittently....not the ignition it would seem. I know zip about the magneto but I'm wondering...should I order one? Will Gasbikes send me one? The kit came last Tuesday so it's within warranty. Your thoughts, as always, are greatly appreciated. Chips X

My sympathies go out to Capt. Campground's family as well.
 
Chips,
When your engine shuts down, will it restart immediately or does it take a while, as if it needs to cool? It sounds as if you've covered all the bases electrically except a visual inspection of the magneto and the wires from it. Closely examine the soldered connections on the mag and make sure the ground wire, the black one, is tight to the mag core where it attaches to the engine.
Also does it shut off as if you pushed the kill button or does it miss and pop before dying? Get back to us and we'll help you solve this.
I assume you have been through the fuel delivery system; Petcock, filter screen, tank is venting properly?
As for the seller sending you a new mag I'd suggest contacting him and asking. He might want the old one back for a warrantee replacement so don't discard it.
Tom
 
The engine didn't restart that Friday. Saturday I took the carb apart to clean it (I had some fuel go through it), put it back together and it started. A few rides around the block, all ok. Then later in the day i was 4-5 minutes into a ride it shut down in mid ride, no pop or sputter, just like a power loss. I opened the mag cover, the black is secure to the core but i can't see if the white & blue are ok, I haven't removed the whole mag yet.
 
It could be a "cooling" issue, whatever that may entail. It will start up again but not every time. It's frustrating since I don't know what is wrong, I can't fix it.
 
I'm sure there are better ways to figure this out, but the first thing I would try, is to put another spark plug in my pocket (any one that has the gap set correctly) and go for a ride. When the bike shuts down again, I'd pull the plug wire off and put the spare plug into it, and let it rest on the top of the head (in a horizontal position, so I could see the gap from above). Then pedal up to speed, pop the clutch, and see if I can see a spark jumping the gap. If not, then you know for sure it's an ignition issue.

If there is spark, then immediately hook back the plug wire to the engine plug and see if it runs. If no go, then it's likely a fuel issue. There's still a chance for a bad plug in the engine as well.

This will at least help narrow down where the fault is for sure. Anyone else have a simpler method?
 
SpandexOrLeather said:
I'm sure there are better ways to figure this out, but the first thing I would try, is to put another spark plug in my pocket (any one that has the gap set correctly) and go for a ride. When the bike shuts down again, I'd pull the plug wire off and put the spare plug into it, and let it rest on the top of the head (in a horizontal position, so I could see the gap from above). Then pedal up to speed, pop the clutch, and see if I can see a spark jumping the gap. If not, then you know for sure it's an ignition issue.

If there is spark, then immediately hook back the plug wire to the engine plug and see if it runs. If no go, then it's likely a fuel issue. There's still a chance for a bad plug in the engine as well.

This will at least help narrow down where the fault is for sure. Anyone else have a simpler method?
Click to expand...
You'll want to be very careful trying this because if the engine is hot you can pull the threads out of the head. The steel spark plug and the aluminum head expand and contract at different rates and when the plug is hot it is tight and you can do serious damage trying to get it out. Let the engine cool first.
Tom
 
2door said:
You'll want to be very careful trying this because if the engine is hot you can pull the threads out of the head. The steel spark plug and the aluminum head expand and contract at different rates and when the plug is hot it is tight and you can do serious damage trying to get it out. Let the engine cool first.
Tom
Click to expand...

Exactly why I stated taking "another plug" along with you. No need to take out the plug in the engine, simply hook up a spare plug and leave it rest on top of the head fins (to run the test). This leaves the hot plug still in the head where it belongs. Perhaps I wasn't as clear about this as I shoulda been.
 
And could have been my inability to read. :) Sorry, Span, didn't mean to imply anything. I was just advising in the case that someone would try to pull a hot plug. Thanks for the clarification.
Tom
 
Well after taking my carb apart, cleaning it, priming a bit more than usual.....it started. I liken it to the gasbike version of blowing on a video game cartidge to make it work. I'm not complaining, mind you.....I am having trouble resizing photos to post but will do so asap. The bike is running well now and I have a frint drum hub/dynamo and new wheels to install next! I can't stop riding this thing! Thanks for the help!
 
I have a GasBike Kit that came with a clutch that did not work. No response to my e-mails. I am going to try one more time before I switch suppliers. Vic
 
I wonder if the cdi is pooing the bed when it gets hot and after it cools off it will work again?
If you can try this, carry a can of keyboard cleaner ride till it dies then spray the cdi with the can upside down spraying liquid on the cdi if it will start right up then the cdi is getting ready to play taps.
Something else to try run a spark plug gap of 0.020" see if that will help. Spark plug wire in the cdi and the plug boot tight?They screw in and out.
Norman
 
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