Cafe Racer Forum banner

Help! Flywheel/magneto problem

1242 Views 10 Replies 3 Participants Last post by  jbranson
So, after adjusting my valve clearances I take the bike out for a spin. Everything seems ok than all of a sudden I hear screaching sound coming from the flywheel cover followed shortly by stoppage. So, I get the bike to a secluded enough area, come back with tools and proceed to check the rotor bolt (there was evidence it came in contact with the cover. However, the bolt is tight! So, my question is what's causing my flywheel to all of a sudden rub on the cover, when the rotor bolt isn't loose? I just got a flywheel remover off eBay and will take that off and see what is going on in there...Only thing I can think of is that "" makes referrences to the starter clutch bolts and how they work themselves loose. Would it be possible for the starter clutch bolts to work themselves loose thus allowing the flywheel (rotor) to loosen on the shaft? Any input would be nice...I've almost had enough of this bike.
1 - 4 of 11 Posts
What kind of bike?

If it's a Honda....and the rotor bolt is still tight...and all of a sudden the rotor is hitting the side cover....that's not good.

The rotor bolt of course screws into the crankshaft snout...if it's truely still tight (and by that I mean screwed in all the way)...the only way for it to move out and hit the cover would be if the crank snout was broken off. Which isn't likely....unless something metal got attracted to the rotor while you had the cover off and then wedged itself between the rotor and the stator...possibly breaking the crank snout or doing some other kind of hidious damage in there.

Remember...just because the bolt is tight doesn't necessarily mean it's screwed in all the way....if it loosened up and the flywheel spun on the keyway it would probably wedge itself out against the bolt and make it appear tight while in fact the rotor had moved out some distance.
Those rotors are pretty tough. But it might have bunged up the taper on the rotor....and crank maybe too. Honda uses a very small key on those just barely sticks up from the crank snout. If the rotor bolt gets loose at all the crank can turn inside the rotor....which drags the key around the inside of the rotor taper and screws everything up.
Technically the rotor key is only to position the rotor for's not meant to keep it in place. The taper fit and bolt are supposed to do that. Many race ignition rotors have no key at all and just depend on a bolt to hold the taper tight.
Don't know the answer to that one.
Someone here will though.
If the starter clutch locked up it might have spun the stater motor really fast while the engine was running and messed up something there. Then you say..could be just a weak battery.
1 - 4 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.