66cc 2 stroke magnito problems

[MotorizedMatt]

Hi guys,

Lately my magnito has been giving me slot of problems. I originally took it to a shop and they seemingly fixed the problem, yet the next day I couldn't get the bike to start after I had ridden it to school. Then I took the magnito out wiped it off and replaced it and the bike ran great again. Now this morning it started up, but died after about half mile and I couldn't get it to start.

Anyone know why I'm having these issues? I know for a fact it is the magnito too, should I buy a new one?

Any insight is appreciated as I need this thing to run since it's my transportation.

 

[MotorizedMatt]

Reason? Was there oil on it? Wet from water?

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There was a very small amount of oil on it.

 

[GearNut]

The only way oil could get in there is if the crank seal is not seated properly or has failed. It is behind the magneto rotor.
It should be installed flush to the surface or slightly recessed in the case.
Also, if the seal is leaking oil out it is also leaking air in which is as bad as an intake leak.
This can cause difficult starting and poor operation.
If you decide to remove the rotor, mark the outer face if it with a sharpie, crayon, scratches, ect. It can easily be installed backwards which would throw off the ignition timing causing the engine to not run at all.
Also, it is much easier to work on the rotor if you first remove the stator, that way you will not be fighting against the magnetic pull between the rotor and stator.
Watch for the woodruff key, don't loose it.
Superglue the key into the keyway in the shaft when you re-assemble.

 

[MotorizedMatt]

Thanks for the info.

Update as of yesterday: I took the magnito off again and there was a small amount of oil on the backside of it, which I wiped off. I'm not sure how, but the blue wire came off, so I soddered it back onto the magnito. After that the bike fired right up, and I rode it around all yesterday night (about 10 miles).

Fast forward to this morning. I start the bike and it runs for about 2 mins then just dies as I had it idling. I started it again and began my trek to work (5.5 miles) and it didn't die once. I'm at work now, and I have a gut feeling that its not going to start come 5pm.

Could that small amount of oil on the magnito be causing my problem?

 

[Al.Fisherman]

I could but I doubt it. If there is seepage as you say, it is really best to replace seal as GearNut recommended. If that is out of the question for the time being, and you are concerned about the oil, and the seal seep (vacuum leak) is not having effect on the running engine, here is is temp solution (I don't want to say fix).
The seal could be seeping from either the seal to case or the seal to shaft which is most likely. Remove the magnet and coil, clean with some break cleaner or carburetor cleaner, or the like...something that won't leave a residue. Take some ATV and smear around the seal (light coat), making sure that the seal to case is sealed. Now take a freezer storage bag (thicker then most plastic wrap), and cut a piece that will be able to fit behind the coil and that all coil screws can go through when the coil is replaced (to hold it in place). Poke a small hole where the shaft will come out. Slide over shaft, replace the coil and magnet. Any oil seeping will gather on the bottom of the magneto compartment from the backside of the plastic and can be checked and cleaned by removing the magneto cover periodically. I had a seal seeping, did this and found out that the seep was between the seal and case. End result was the RTV did a permanent fix.

 

[MotorizedMatt]

Thanks for that info I'm deffinately going to try that later. Could that little amount of oil actually be it though? And when you say seal is that behind the center spinning metal peice? Because I don't remember seeing any seals from when I took the magnito off, it looked like the oil was coming through the screw holes.

 

[BiMoPed]

The screw holes do not go all the way through into the crankcase
unless Chinese "quality control" screwed up.

Yes, the rubber seal is around the shaft. There is one on both sides of the
motor.

If you can see or feel behind the magnet is the rubber seal flush with the case?
Sometimes they are not not pushed all the way in.

Thanks for that info I'm deffinately going to try that later. Could that little amount of oil actually be it though? And when you say seal is that behind the center spinning metal peice? Because I don't remember seeing any seals from when I took the magnito off, it looked like the oil was coming through the screw holes.

 

[MotorizedMatt]

The screw holes do not go all the way through into the crankcase
unless Chinese "quality control" screwed up.

Yes, the rubber seal is around the shaft. There is one on both sides of the
motor.

If you can see or feel behind the magnet is the rubber seal flush with the case?
Sometimes they are not not pushed all the way in.

I will check this later when I get home, but If the rubber seal wasn't pushed in all the way wouldn't it hit the spinning metal? Either way I'll take it off and check the status of those seals.

 

[MotorizedMatt]

Alright it's deffinately leaking from the seal behind the shaft, would epoxy be okay to put around the seal to prevent leakage? Or is the method stated above the best option.

 

[GearNut]

Epoxy might work but it will be very difficult to work with later.
Black or red ATV silicone would be much better.