Starting Problems

[clive]

hi ya im quite new to trials and the forum, i have recently bought an beta techno 250 and having a few problems getting the flywheel to stay still when tightning the shaft nut up. i was told it might need a new woodruff key which i have bought, but am not sure were to fit it any help would be very kindly recieved thanks to anyone who does know cheers clive

[bob]

Probably not the woodruff key, this sits in a small slot in the crankshaft tucked away about half an inch back from the outside edge of the stator core.

To do the flywheel nut up, you'll either have to remove the weight (if it is still on) and put some bolts into the holes (not going through the other side) and make something to attatch to it to hold it in place, or put the bike in top gear then get somebody/thing to hold the back brake on and tighten the flywheel nut. You might find it easier to use an air powered impact wrench. Do it up to about 140nm.

Hope I explained that well enough.

Bob

[andy m]

Hi, remove the flywheel and sparkplug, turn the engine over slowly keeping an eye on the crankshaft about 2 inches from the thresde end. You should see a machined cut out where the woodruff key sits in. There may be the remains of an old one in there. When you find it slot the new key in if its not a tight fit put a little bit of grease to help locate it, only a tiny amount . Then with the slot at 12 oclock and the new key in place slide the flywheel on to the crank, before you slide it on look down centre of flywheel to see where the key locates, it will be a long slot. Carefully slide it on to the crank and make sure its located properley and tighte the flywheel up. Thats it your timing should be right as long as nobody has messed with anything else. Good luck

PS. Welcome to T C.

[furse]

Beta's did have problems with wudruff keys and electrics, a fly wheel extrcator is the easyiest and safest way of removing your flywheel, they're not expensive.

Theoretically there should not be any stress on the wudruff key, it is a sign of a poor fitting flywheel on the crank.

If you keep braking wudruff keys it may be worth checking the fit

One method of trying to get a better fit is to remove wudruff key from its slot,

put some grinding paste on crank then push flywheel back on and spin it around the crank shaft (no need to put nut on)

remove flywheel, then clean shaft well,

put some chalk all around shaft and again put flywheel on trying not to touch crank till its fully on,

rotate flywheel, pull off and see if any chalk is left on crank.

there shouldn't be any solid traces of chalk, if there are then the shaft isn't making contact with the flywheel,

more grinding paste where the chalk has gone and rotate again.

The other problem could be bottom stator plate or top coil, there is a place down south that can test and rewind bottom stators for a little less than new replacement.

I take it you've tried changing a plug, Beta's do like plugs.

Also disconnect kill switch.