Is there not likely to be a difference in the disc valve between SWM and Aprilia?

I don't know - anyone ??

Heres a flywheel that I took from a 240 Armstrong Rotax, this ones been reduced by 50% vertically. Might give it a try to see what difference it makes.

Zip tye your back mudguard first.

Resurrection time - just weighted a 240 climber flywheel - 4kg !!!

But is that because there is only weight on the ignition side ?

Air cooled Aprilias don't have a weight on clutch side either.

Was thinking of trying a lighter flywheel but dont want to do mods I cant reverse. So can I simply remove the weight from the clutch side on a 280 swm ?

Pretty sure you can, Martin would be the man to confirm. Stevens trials have the proper replacement nut.

Do you know how to lock the crankshaft ?

Uh oh are you about to tell me I cant do it with an impact gun. Never had clutch case off yet.

Yes, you can run without the counterweight, the early red/white SWM's and the later Aprilia TXRs ran with just a nut. You will need the correct nut, I have a couple here if you want one

You dont need a impact gun to remove the weight, just a half inch drive ratchet/bar.

Either hold the flywheel, to lock the crank and remove the counterweight (std right hand thread).

Or you can lock the crank directly......look between the fins on the crank case, just below the exhaust port, and there is a 13mm hex head bolt. Take this out, poke a clean screwdriver down the hole and it will touch the crank. Slowly rotate the crank, and when it reaches top dead centre there is a hole. If you find a long M8 bolt and screw this in, it will lock up the crank to remove the counter weight or flywheel nut. Also handy, if you need to set the disc valve.

Cheers

Martin

Counterweight now removed so will try at trial on sunday and report back

Don't think you will notice a massive difference, you going to Longframlington ?

Yes see you there ?

Weather permitting