2-stroke magneto

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Charged-Reacter

Charged-Reacter

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Dec 12, 2008
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west-central Illinois
I was doing a check on my Grubee Skyhawk 66cc engine and
started to unloosen the screws on the outside cover of the magneto and noticed oil dripping out the bottom front screw. Is this a sign of trouble to
come? This engine has only 3 1/4 gallons of fuel ran through it.
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Sounds like a bad oil seal... I don't know if oil on the mag will cause problems or not? Just don't let the oil get to heavy inside the cover; & run it until it dies!!
 
Charged-Reacter

Charged-Reacter

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Dec 12, 2008
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west-central Illinois
I rode the bicycle about 1 1/2 miles before I had to pull
the clutch in to idle at an intersection and the engine quit
running. Tried to restart with no luck. I peddled up a good
size hill and went fast down it and engaged the clutch and
it started and ran until I got home with it and at idle died
again. This engine did not last long at all. It was fun while it
lasted thou. Engine is still under warranty but I did not break
the engine in at 16 to 1 as recommened in the book.
 
X

xlite

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Jun 18, 2009
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I break all of mine in with 50:1 Walmart oil.

And note that oil does not conduct electricity. It's what they use for dielectric inside industrial transformers and capacitors.
 
X

xlite

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VENICE BOY said:
How about the gas thats mixed with the oil? will that conduct the electricity?? ;)
Click to expand...
Nope. Even if it has LEAD in it. And note pure water is a poor conductor also.

As a general rule if it's metal it conducts, if it's not it don't. Generally :).
 
X

xlite

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VENICE BOY said:
The real question is, 'could it short out the mag coil?' Maybe?
Click to expand...
Not short but I think gas might dissolve enamel on the super thin magnet wire. Water might cause electrolytic corrosion. Although my magnetos have been exposed to both without harmful effects (knock on wood). Using that white wire seems the only common factor in my case.
 
2door

2door

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Sep 15, 2008
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If there's oil in the mag cover the crankshaft seal behind the rotor (magnet) is gone. An oil soaked mag will die. I had the same thing happen to one of mine. I replaced the seal and mag and that is now the best engine I have. The problem was the factory did not drive the seal in deep enough and the magnet rubbed it and wore it out. A leaking crank seal will cause a lean condition and give you the problems you described. The seals are available from PistonBikes. Motorized Bicycles Gas Bike Engines Gas Powered Bikes Motorized Bicycle Parts

Carefully remove the rotor using two screwdrivers on each side and 'wiggle it off. I say be careful because excessive force can actually bend the crankshaft. It's only about 5/16" in diameter at the point where the magnet goes. There is a woodruff key in the magnet that engages the shaft, don't loose it. Pick out the old seal and using an appropriate sized driver, replace the seal making sure it is completely seated in the bore and there is no interference with the magnet after it is reinstalled. A little oil on the shaft and seal while installing will keep it lubricated until the engine runs again. Hope this helps.
Tom
 
Last edited:
BarelyAWake

BarelyAWake

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Jul 21, 2009
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I don't have this prob (thank gawd) but I'm glad I read your post anyway Tom, that's a procedure I could see happening sooner or later lol
 
X

xlite

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Yes, thanks, that was an excellent how-to for magneto bearing. Saved to disk. It would be nice to see somebody do one like that for replacing clutch pads which is another tricky procedure.
 
Charged-Reacter

Charged-Reacter

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Dec 12, 2008
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west-central Illinois
I could not stand not riding a 2-stroke china girl engine any
longer, so I decided to put the CH80 back on my other bicycle.
When I completed the engine installation , I was ready to roll
again, so I thought. The CH80 would not start up. I knew this engine
did not have oil in the magneto case. So I examine the bicycle set-up
for the most obvious problems first. I knew I had my ignition coil kind
of close to the engine and exhaust. I put a new ignition coil on the
bicycle and tried to start it up again and it started right up. The other
engine has small amounts of oil in the magneto case that is golden
brown color but I think now that was not the problem. At least I am
motor bicycle riding again with a happy time. At least I will have the parts
to fix the other engine when the thin seal gasket leaks alot more than it
has been doing.
 
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