any ideas how to make 1/5 turn throttle?

[shwnrttr]

i was looking for some ideas on modifying the stock throttle to make it a 1/5 turn or even 1/6 turn. ive seen some mods for street bike throttles by adding larger cam in the throttle grip, but i dont think that would work with these cheapo throttle grips. i was thinking of two cable pulleys together to change the ratio. if anyone has any ideas or mods they did themselves i would appreciate it.

 

[CroMagnum]

Back in 1973 I bought a DKW 125 to race District 37 Desert, Lightweight Division II. Like today it was generally thought that 1/4 turn throttle was probably optimal for dirt bikes. But that little "Deke" was such a screamer with an extremely narrow powerband that you never used half throttle - it was either full or off. What you really wanted was a toggle switch. Besides, less movement meant less fatigue on races like Barstow to Vegas that approached 200 miles in length.

The Deke had an odd 27mm Bing carb, and like all the German bikes came with really nice Magura hardware. So I went down to the local Maico dealership and bought a factory Magura throttle assembly from a Maico 400/501 that was made to pull a 46mm Bing slide up in a 1/4 turn.

That made the little 27mm slide lift from idle to full throttle in less than 1/8th of a turn. I had my toggle switch! Success!!

So if you really want a super-quick throttle, find a twist grip for a big, open-class dirt bike and you'll get your 1/6th turn or better for full throttle.

 

[dun_it_too]

on my 66/80, simular issue, not enuf 'tweek'. Pulled rich on my mix, shorthened up adj on throttle and carb. But I did port the in and out and open in a bit w/ a fresh cnsII carb, boost bottle worth the loot, just get a tight seal. Billet yrself, boost pipe to close to intake w/their intake, heat...

 

[dun_it_too]

42 MPH level grnd w/ 36T...

 

[shwnrttr]

Back in 1973 I bought a DKW 125 to race District 37 Desert, Lightweight Division II. Like today it was generally thought that 1/4 turn throttle was probably optimal for dirt bikes. But that little "Deke" was such a screamer with an extremely narrow powerband that you never used half throttle - it was either full or off. What you really wanted was a toggle switch. Besides, less movement meant less fatigue on races like Barstow to Vegas that approached 200 miles in length.

The Deke had an odd 27mm Bing carb, and like all the German bikes came with really nice Magura hardware. So I went down to the local Maico dealership and bought a factory Magura throttle assembly from a Maico 400/501 that was made to pull a 46mm Bing slide up in a 1/4 turn.

That made the little 27mm slide lift from idle to full throttle in less than 1/8th of a turn. I had my toggle switch! Success!!

So if you really want a super-quick throttle, find a twist grip for a big, open-class dirt bike and you'll get your 1/6th turn or better for full throttle.

good info thanks, i was just going through some of my junk, i found a throttle grip for a 1993 yz 125cc. it appears to have a larger cam. unfortunately its in bad shape. its in need of repair(jb weld)

 

[dracothered]

Which motorcycle makes used 7/8" handle bar twist throttles?

 

[shwnrttr]

ended up using the yz 125 grip after repairing it with jb weld. so far im pretty happy with it. thanks again cromagnum.

 

[wayne z]

You could make a reverse "snatch block" system. I'll describe the cables and you can fill in with your imagination what it would take to fab a bracket to hold it all. This would reduce the standard rotation of the twist grip to half of normal but make the throttle twice as hard to pull.

Devise a way to attach a small ball bearing pulley with a bracket that the twistgrip cable would attach to above the pulley.
Then bring the carb cable from below, around and over the pulley, with the end attached to something solid and unmoving.
Now, when the upper cable is pulled, the free end of the lower cable will travel twice the distance that the upper cable moved.

I've done the same thing but reversed, to the brakes on an ultralight to give more power to the brake arm for stronger brakes.

 

[shwnrttr]

You could make a reverse "snatch block" system. I'll describe the cables and you can fill in with your imagination what it would take to fab a bracket to hold it all. This would reduce the standard rotation of the twist grip to half of normal but make the throttle twice as hard to pull.

Devise a way to attach a small ball bearing pulley with a bracket that the twistgrip cable would attach to above the pulley.
Then bring the carb cable from below, around and over the pulley, with the end attached to something solid and unmoving.
Now, when the upper cable is pulled, the free end of the lower cable will travel twice the distance that the upper cable moved.

I've done the same thing but reversed, to the brakes on an ultralight to give more power to the brake arm for stronger brakes.

thats what i was originally was thinkin of doing but im very happy with the yz throttle. it had a large mukini slide carb. so it did just what i was wanting it to do. il have a build thread soon when i finish the bike.