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Noisy Stator/flywheel

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Ive been doing some maintenance today on my carb and when I put it all back together I was turning the engine over by hand, I noticed a grinding coming from the rear of the engine in the location of the coil :-(

Is the coil fixed to the back of the engine ? I'm guessing it shouldn't move about as the flywheel rotates around it?

Guess I'm having my engine off tomorrow! Better not be bloody flyable or I may cry!!!


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Well I've just taken the engine off and removed the flywheel.. One of the studs was loose and one pole of the stator is mangled! Also two of the magnets in the flywheel are cracked.

The electric box is covered in cracks and falling apart so need a new one of them as well :-(

Parts bill £100 plus postage, could be worse ...

Might use it as an opportunity to get the frame re powder coated as its stripped down.

Tom :(

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If you're thinking of powder coating, take a look at stove enamelling. It's thinner, lighter, tougher and can be touched up if you scuff it. The bake temperature is safe for heat treated aluminium alloys (although I would check with your supplier).

I've used both powder coat and stove enamel on wheel rims. Stove enamel will stand up to tyre levers while powder coat didn't.


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I went to reassemble the stator/flywheel this morning and discovered the reason for the original failure, the shaft appears to be bent (about 0.4 runout) so the stator was rubbing on the flywheel ! :-(

it looks like its had runout for a long time (judging by the groove around the inside of half the flywheel)

Not really sure what to do now, do I strip the engine completely and straighten the shaft (not keen!) or do I stick the flywheel in the lathe and skim 0.5 from the magnets? ( not even sure if that's possible as I've never tried turning magnets before :? )


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You absolutely need to get the flywheel running true.

Machining magnets is not good. If they're not made from the hardest substance in your workshop (I can attest that Lucas Magneto magnets are!) then the interrupted cut will impart a series of shocks which will reduce their magnetism.

The magnetic field surrounding a permanent magnet dereases as the cube of the distance from that magnet. If you double the gap, you will have 1/8 of the field strength through the coil.

A wobbly flywheel will cause vibration. Even if you correct the static balance, their will be a dynamic imbalance. Vibration will cause further damage to your engine and increase fatigue in the frame and prop.


Bailey 175

Ozone Indy

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I would be very cautious about trying to straighten the crank.

If not done absolutely spot-on, it could still cause issues with the main bearing.

Speak to someone like Stan Stephens, Mick Abbey, Graham File etc. They deal with 2Ts all day long!

Sod the poncey polish job and get the motor sorted first!!

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Yes worrying about the frame finish is now the least of my worries!

Spoke to a friend who said its very unlikely to be bent, but more likely that the two halves have gone out of balance. Got some v blocks and 2 clocks so will get it out tonight and see what's going on, but saying that if I think it looks dodgy I will just replace it..

Need to get the bloody ring gear off first tried pulling it of with no luck, will try with a bit of heat in the minute.

Tom :acro:

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How or why the crank came to be out of alignment is a bit of a mystery?

If you can get it back to within tolerance, it may be worth just spot welding the main wrist pin to the webs. They can easily be ground off if you ever need to rebuild the bottom end.

Only use a copper faced mallet to straighten the webs!!

Keep us informed on this one Tom.....

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Well I managed to strip the engine down tonight got the head off, getting a bit late to be banging around so will leave splitting the crank case for the morning. the head seal and o-ring need replacing, as does the ring gear.

Might as well get some gasket paper and replace them all well I'm at it.


Tom :D

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Well I split the case this morning and started sorting the crank, managed to get it to within 0.05 but will try and get it better this afternoon. Need to replace the bearings as they don't feel fantastic, need to get a bearing extractor first though and find out what bearings they are.

All good fun :roll:



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Use a scraper VERY CAREFULLY, then polish using wet/dry 1200, then Autosol if you want to really get a shine!

Carbon has a much harder time sticking to shiny surfaces.

Treat the cylinder head the same, shiney=good!!

Chuck a set of rings in if the piston has not done too many hours.

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