The pic below is the mock up of the throttle assembly, the gear that meshes with the throttle grip will be dropped in to proper alignment once the silicon holding the rubber grip sets up. I used a Harley, aluminum twist grip, and lathe machined it and the vertical gear which was treated with a chemical known as Acid Etch and Alodine, so that the steel (brass plated gear) and the aluminum twist grip can co-exist without dissimilar metals oxidizing.
In the next pic below, is a little detail on the final sprocket (also steel that was brass plated). Although it's difficult to see, the piece I made to capture the 'lead ball' of the throttle cable is made similar to the stock cable using a brass cylinder that I've designed a pivot so the cable can 'rotate' as it goes past centre.
The next photo below is a view from the headlight back along the handlebar, to show the 'piggy backed' sprocket and mitre gear all welded machined, and brass plated. Note, that all the screws and washers/nuts are stainless steel, as is the #25 sized chain. I used the stock throttle cable without the 90 deg. end on it… and fabbed up a hollow stainless bolt that made it a straight on fitment.
The last pic below is a shot of the 'nearly done' set up. Once the throttle grip silicone sets up, the assembly will be dropped about 1/8" to match the throttle grips mitre gear and the driven mitre gear. I used 'oil-lite' bronze bushing on the rotating parts nicely buttered up with Lithium white grease. It's actually as smooth as the stock set up!
I guess this begs the question…. "WHY?" Stock was fine, and now I've added a 'hideous mechanical contraption' to an otherwise OK bike!
Well, the best I can offer, is I truly like the 'Steampunk Mad Max' look of machines and this is one way to express my idiosyncrasies. This was possible because we finally got our lathe up and running. And I just can't leave well enough alone! Maybe it's like when 4 years ago I made the chain driven hand shifter for this bike… which in my opinion is much much better than the foot shift set up that factory came up with. I'm far from being done with new ideas! Oh, and for those that are a wee bit concerned… I doubled up on the throttle return spring, and because of the wider outside dimensions of this chain drive assembly has a mechanical advantage that makes idle to wide open throttle a little better than a 1/4 turn throttle, and it's easier to twist than stock.
Lucky you don't have a MILL or you'd be making an aluminum primary case for the throttle assembly. It looks like it will work and no one else has one. I like it just because I like it.
Great ingenuity and fabrication Ric. I really like the theme you are going with. Looking forward to the next addition to bring your bike further into Mad Max Dom.
DeLand, FL.
"This is just one of the many reasons I love V8Bikers; able to openly display T&A, curse, say what you will;
able to be a fucking man here. Thanks Bill" - Grand Canard
Iron Maiden wrote: Ric that is quite ingenious and very cool looking but I believe all this creativity is due to your long winters and this year was especially long.
Looks good Ric...Although I blamed it on brain freeze!
Ric that is quite ingenious and very cool looking but I believe all this creativity is due to your long winters and this year was especially long. 
