Shorter Throttle

[tayyo789]

So I've got a DS650, with a ton of stuff done to it, used only at the dunes, etc...
Right now, its got a Lectron 48mm carb, and a Moose thumb throttle. With this size/brand/design carb, the throttle travel is extremely long, causing it to be a very awkward process to be able to use it to its potential. I'm trying to come up with some ways of trying to shorten the amount of thumb movement it would take to open this thing up. I had a twist throttle, which works better, but is just too awkward to use on a quad, and I would really wish to stick with the thumb throttle. I know some of you out there are creative genuises when it comes to stuff like this, and I'm looking for your help

[450Rida]

put shorter cables on it????

[tayyo789]

I don't think I was clear enough. I want shorter thumb travel, while still opening the carb up all the way. With such a big carb, my thumb has to move too far in order to open it up.

[wilkin250r]

That may be tough, or it may have a really easy solution.

Most of the ATV handlebars are the same diameter, and most all of the thumb throttles on the various quads are all single units, meaning they aren't a shared combination throttle/brake mount unit. As such, other brands of thumb throttles would probably mount up on your DS650.

I'm not an expert on each and every one, but I would look into other brands of thumb throttles, especially from the bigger quads that are likely to have bigger carbs. Perhaps a thumb throttle from a 700 Raptor would be exactly what you're looking for. You might possibly need a custom cable to tie it all together, but custom cables really aren't that expensive ($40).

[tayyo789]

Ya, cables wouldn't be a problem. I've got a shelf full of them from running different carb/throttle combos on other bikes. I guess the biggest problem is that this carb is huge, and it doesn't have a spring and pulley system on it. The cable drops in the top of the carb, and atteaches directly to the slide, so the thumb travel is equal to the slide travel, if that makes sense.

[wilkin250r]

It might be possible to modify your throttle to give a longer throw to it, but I was thinking you might be able to find one that already had a longer throw.

Have you looked at other thumb throttles? Raptor 700? Honda 700? Any of them have a longer throw to them?

[tayyo789]

I haven't had one of those, but it's definitely worth a shot. I want a throttle that takes up the same amount of cable, with shorter thumb movement. Maybe an assembly that has a cammed lever arm in it? I know thats how some twist throttles work.

[witech]

I have some thumb throttle housings. What length throttle pull do you need. it should be easy to measure by just removing the cable from the throttle housing and measure how far it pulls from closed to open.

[tayyo789]

Well, since the cable is hooked directly to the slide, theoretically it should move 48mm. I'm not going to be home for a few more days to look at it again, but if I had to make an estimate that's what I would say

[wilkin250r]

My second question is, how much are you willing to spend? It's entirely possibly you could talk to a good machine shop, and custom make a new cam inside your throttle to give you a longer throw. It might not be cheap, it would probably be a $150 or so because it's a one-off custom, but it's possible.

[tayyo789]

Thinking about it, I'm wondering how the drag racers do it. I might post in a drag forum too, since they are always dealing with huge carbs

[witech]

The throttle housing I have has a 32mm pull on it.

[mcginty33]

try a 250r thumb throttle housing, I saw one on a yfz one time and the throw felt really short.

[tayyo789]

It has to open a 48mm carb, with the cable being directly connected to the carb slide. Essentially, I need the lever arm in the throttle housing to pull 48mm of cable, without the thumb lever moving that far. It makes for a very uncomfortable ride

[witech]

http://www.chrome-addiction.com/p-moose-racing-atv-thumb-throttle-blue-m78001-10133979.php?r=thefind
These are close. Ill bet you could grind a little out of the inside of these housing to get 4mm more.

[witech]

http://www.lectronfuelsystems.com/products/billet_thumb_throttle.html
Problem solved ....:D

[wilkin250r]

But I'm not sure one of those throttles will work. From what I understand, his stock throttle will open his carb 100%, that's not the issue. It's the fact that he has to push it so far to accomplish 100% open that it becomes uncomfortable to push it so far.

An aftermarket throttle might solve the problem, or it might be the same thing. He might still have to push it really far to get 100% open. And that's kind of an expensive gamble.

[tayyo789]

I have a Moose throttle on right now, and that's what I don't like about it. The Lectron one will work, I'll have to try one on the drag bike I'm building with dual 40mm carbs