Lightened alternator GT750 (and other crank lightning stuff)

Arne · Post by **Arne** » Sat Jan 31, 2009 1:07 pm

I'm considering lightening my rotor for the GT750 project to increase acceleration, de-acceleration.

Anybody ever done this?

Did you mutz about with this Watercooled?

I've got a couple of them, so I imagine I'll lighten one a spot and then see if I like it, if I don't it's a super easy part to switch out.

What do you think?

Thanks - Arne

http://www.practicalmachinist.com/vb/sh ... p?t=158836

Post by **Suzsmokeyallan** » Sat Jan 31, 2009 4:00 pm

Arne just where on it are you planning to lighten the rotor,

Arne · Post by **Arne** » Sat Jan 31, 2009 4:58 pm

Suzsmokeyallan wrote:Arne just where on it are you planning to lighten the rotor,

Inside the perimeter of the electromagnet poles and around the left and right flat faces.

Barry S. · Post by **Barry S.** » Sat Jan 31, 2009 7:07 pm

The crank weighs a ton, I doubt you would notice much difference unless you could shave a pound or two.

Arne · Post by **Arne** » Sat Jan 31, 2009 7:45 pm

Barry S. wrote:The crank weighs a ton, I doubt you would notice much difference unless you could shave a pound or two.

Well, the whole rotor weighs like three pounds. I'll try for a pound, which is 3.53 square inches.... I think I can get that much steel out of it.

I guess we'll see! Arne

water cooled · Post by **water cooled** » Mon Feb 02, 2009 3:57 pm

Sorry Arne,

I decided to pull the entire rotor and remove the rest of the alternator completely. I only need a couple minutes of operation for each pass so an alternator is not in the cards for me.

However, I think SuzukiDave may have done a lot in this area. He focused on a Polaris charging system I think.

I like your approach. Every ounce you can get off the end of that shaft makes a difference. I just finished the left side (starter clutch assembly).

Good luck Arne and keep posting pics...its great to see your progress.
Kevin

tz375 · Post by **tz375** » Mon Feb 02, 2009 8:13 pm

Kevin,

Now you're talking. Who needs an electric foot anyway. Throw out the starter, solenoid, wiring, push button, drive gear pair, clutch assembly and then cut down the crank gear and what's left of the clutch hub. You might be amazed how much weight is hiding there.

Arne,
Replace the two front disks with something modern and save about 8-10 pounds of unsprung weight. For ideas, try here:

http://pinkpossum.com/GT750/phattrakka2/p5brakes.htm

water cooled · Post by **water cooled** » Tue Feb 03, 2009 10:28 am

Richard,

Got all that done two weekends ago. Thanks for the pics of the starter clutch hub you posted. I didnt cut mine down to the extent you did, but certainly removed a lot of material and weight off the starter clutch hub.

I also removed the breaker cam bearings and sized the smaller bearing OD. Looks like a 35mm freeze plug (wlesch plug) fits nicely to block off the oil path to the breaker housing. Bought the freeze plug from NAPA for $1.45. Should to the trick/.

Suzukidave · Post by **Suzukidave** » Sat Feb 07, 2009 10:17 pm

Because i didnt need the added width of the points side any more i trimmed my cover back and then made a nice cover plate .

tz375 · Post by **tz375** » Sat Feb 07, 2009 11:13 pm

Nice cover Dave.

Arne · Post by **Arne** » Sun Feb 08, 2009 1:50 pm

Suzukidave wrote:Because i didnt need the added width of the poibts side any more i trimmed my cover back and then made a nice cover plate .

Did you cut off the end of your crank? Perhaps you have a photo of that somewhere? Thanks, Arne

Suzukidave · Post by **Suzukidave** » Sun Feb 08, 2009 3:44 pm

Arne wrote:
Suzukidave wrote:Because i didnt need the added width of the poibts side any more i trimmed my cover back and then made a nice cover plate .

Did you cut off the end of your crank? Perhaps you have a photo of that somewhere? Thanks, Arne

No , everything is still on the end of the crank includeing the starter clutch . I really could have made the cover even shorter without any problems but i wanted the engine to stick out the sides of the frame about the same amount just for looks plus the Phat pipes are going to ground before the engine side covers ever do

water cooled · Post by **water cooled** » Sun Feb 08, 2009 4:06 pm

Dave,

How did you block the hole where the bearings were removed from? Is there more going on with that cover or did you use a freeze plug?

Suzukidave · Post by **Suzukidave** » Sun Feb 08, 2009 6:14 pm

The cover sits flat with the machined off side so i was just planning on some 3 bond between the covers .. really the best thing would have been to weld the two pieces together .

tz375 · Post by **tz375** » Sun Feb 08, 2009 7:40 pm

Dave,

Did you block off the drip hole at the bottom of that case to stop trans oil making its way outside?

Lightened alternator GT750 (and other crank lightning stuff)

Lightened alternator GT750 (and other crank lightning stuff)

Alternator Rotor