October 23, 20178 yr Hi guys, Picked this up at weekend as a winter project, runs ok but rough. ( sorry can't load the photo of the bike ) The question is, I went to check the points and the flywheel nut was hand tight. Took it off with the flywheel and it was really wet and oily at the rear of the flywheel. Began to delve in as you do ( only use to Bultacos ) and I was stopped by the large disc that is retained by three large screws. I can get it to rotate but not release, it seems to house a bearing on the crank, how do I get it off guys. And yes for you eagled eyed chaps, the woodruff key is mangled, I've no idea how it ran, it fired up first time. Many thanks.
October 23, 20178 yr I use a 3 legged puller, plus hot air paint gun to warm the casing. It your going in that deep I would replace the bearing while your at it. You need to disconnect the wiring and pull it through, ideally. Where the wiring goes through the casing is a possible entry point for water, sanitary silicon does the job if the grommet is mangled. On reassembly seal the bearing carrier, and also the outer casing with a small amount of sanitary silicon. The breather (buy the timing mark) should be clear, with a transparent tube up under the tank.
October 23, 20178 yr Author Thanks b40rt, think our paths have crossed before. Are we aiming to get the plate casing off with the bearing, or leave the bearing on the crank. The casing does seem to be rather fragile. Ill give it a try, thanks.
October 23, 20178 yr 24 minutes ago, chappo said: Thanks b40rt, think our paths have crossed before. Are we aiming to get the plate casing off with the bearing, or leave the bearing on the crank. The casing does seem to be rather fragile. Ill give it a try, thanks. "think our paths have crossed before." 2 day at Lake District ? Method above should leave bearing on crank, casing is stronger than it looks. (famous last words ...)
October 23, 20178 yr Yes, b40rt know what he is talking about. Give it a (careful) try. Just a short note on the old woodruff key issue. The key is not needed at all, really. It is just for helping with a rough timing at assembly, nothing else. Use a small chisel and perhaps your hot air gun to remove what is left of it. Then grind the flywheel and the the crankshaft carefully with old-fashioned valve-grinding paste until both surfaces has a smooth grey color (can take a little while). Use a timing disc or an indicator through the spark-plug hole to get the timing right and carefully tighten the flywheel nut. Check the timing again and fully tighten the nut, check timing again... The key is just for positioning, not for holding the flywheel. I have not used keys for a couple of decades, just carefully positioned the flywheel until the timing is according to basic spec, before starting to slightly try altering the timing to suit track and rider. Works on all 2strokes in mx, road racing and on the odd old Rotax, too.
October 23, 20178 yr Twist the stator backing plate clockwise and tap it from behind with a block of wood and a small hammer. Hit it evenly on the rear of the 3 cover mounting points...dont beat the hell out of it as they will crack or break, but a few gentle taps that move it 2 or 3 mm at a time will get it off. If you are lucky the bearing will come off at the same time, if not 3 arm puller is required.
October 23, 20178 yr Author Thanks all, heat gun and even pressure released it, it’s off. But strange to then find an external crank bearing !! I take it there’s also an internal main bearing.
October 24, 20178 yr Yes, internal main bearing....the additional bearing is to cope with the heavy flywheel. Motor parts list here that will help http://www.motoswm.co.uk/tech/
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