EFM Autoclutch for YZ490 / IT490 / WR500

[ws6transam]

Garry Buzzeli of EFM Autoclutches just mailed me back my modified clutch with the autoclutch on it. The machining looks great!

I'm hoping to install it over the next couple of days. He's made it as low profile as possible in order to see if we can fit it into the .230" of clearance that we have in the existing clutch cover. If it don't fit, then I will mill the top off the cover, weld in 1/8" bead of magnesium, surface mill to get it flat, then re-weld the cover's top back into place.

So here's to crossing our fingers & hoping it's low enough!

He was surprised to see that the clutch backet has 16 fingers, and I assume that meant he had to generate a new CNC program for the clutch.

 

[BadgerMan]

Hopefully you will still be able to fan the clutch to get some extra drive out of the corners. ;)

 

[ws6transam]

Yeah, there's still a clutch lever *for now*. It'll be a one-finger clutch with only a small amount of movement to disengage it. I'm Considering the removal of the foot brake altogether, and relocating the rear brake to the former clutch position. Think "mountain bike" brakes: I'm told it works really well in terms of braking control. The clutch'll go onto a small decompression lever or something similar.

I just dropped off my clutch cover at Boos Machining/Michigan Gear along with the blueprint on the modifications. We're either going to saw it open, add .300" of magnesium then reweld, or else weld in four screw bosses, and CNC a complete clutch cover out of 6061-T6 that bolts onto the modified Yamaha piece. The second option will enable me to pop it open and do fast adjustments of the clutch, if necessary. It's adjusted with shims and small circular leaf springs in order to affect engagement RPM.