Removing rotor and stator for drag racing

[RacingJake]

Hi all,

Can you remove just the rotor from a 82 GS1100E and still use the starter assy. Going to drag race the bike only with a total loss system.

Thanks Jake

[cbxchris]

Unless you do something to replace the rotor the answer is no. Best thing to do is get a engine plate and put on it with a tapered starter nut. Then get a car starter to crank it...for drag racing its the only way to go.

[Paul]

Be careful, when you remove stator/rotor it can unbalance the crank, which may lead to premature crank failure.
I never rebalanced mine & got away with it, but I know a lot of guys who snapped cranks.
As Chris says, you will have to fit a starter nut & use a car starter.
:roll: Unless you push start it all the time :roll:

[Anonymous]

Just curious Paul - The crank is balanced separately and the rotor is not keyed. It should also, then, be a balanced assembly. How could this make any difference?

[Paul]

I don't know - as I said I didn't rebalance mine & never had a problem, but I know guys who had cranks snap after they had removed rotor.
It was meant to be something to do with the rotor exerts a load on to the end of the crank while it is producing electricity, & when you remove it the load vanishes, but the load is (was!) a rotational load & it affects the crank. I'm not a student of the physics & mechanics involved here, but I'm sure that somebody here will know more about it & may tell us!

[Anonymous]

Just curious Paul - The crank is balanced separately and the rotor is not keyed. It should also, then, be a balanced assembly. How could this make any difference?

People snap the crankshaft on racing and drag motors because of harmonic loads, not balance loads. It's not a matter of having something eccentric hanging off the shaft, its the ulstrasonics that build up in the shaft.

A harmonic balancer, the rubberised fanbelt pulley on the front of your car motor, is there to damp down these harmonics, especially on longer straight six motors. Some people fit something similar to race motors when they take off the rotor/stator.

Kim

[cbxchris]

There are two plates offered. One has a bearing for this purpose to support the crank shaft. The reason one is offered without is many cranks have a end that does not run true and it would bind up on the support bearing. I have forgitten now what the spec was on how true your end must run to use the bearing plate. Very seldom will you see a roller bearing crank break unless under a severe load like drag racing and with a big engine.

[Anonymous]

There are two plates offered. One has a bearing for this purpose to support the crank shaft. The reason one is offered without is many cranks have a end that does not run true and it would bind up on the support bearing. I have forgitten now what the spec was on how true your end must run to use the bearing plate. Very seldom will you see a roller bearing crank break unless under a severe load like drag racing and with a big engine.

The guys at murdoch racing tell me that the cranks usually suffer dammage at the end of the 1/4 race, when the throttle is rolled off too quickly.

[cbxchris]

You are correct. When I went throught he line I chopped the throttle...pulled in the clutch and kept her reving some for oil pressure(turbo). Seen countless engines let go when someone let them slow down with back pressure...usually a rod lets go. Everyone should try once to get a clutch lever pulled in with a lock up on a bike...

[Anonymous]

gotta agree with swanny we always removed rotor for road race never saw one snap a few twisted welding cures this seen a few on drag bike
go west big motors big comp big bang
ozman