Push Pull Thumb Throttle
Posted December 01, 2000 - 04:43 PM
Posted December 01, 2000 - 08:27 PM
good luck, huge
p.s. sorry to hear about the arm
Posted December 02, 2000 - 04:59 AM
I also installed a new throttle cable this week as my old one was frayed at the carb.
The only reason Yamaha installed two cables is to give the operator a chance to physically close the throttle if it becomes stuck... I looked at the carb and before removing cable only hooked up the top one... the pull cable, it worked fine as the carb has a return spring on the slide...
A friend of mine broke his wrist about 8 months ago and rides Vet class on a YZ400, and was requesting the same device you are seeking, I will check with him and see if he actually installed a 4 wheeler throttle device... will let you know either way..
Posted December 02, 2000 - 08:28 AM
4 stroke have much higher intake velocities than 2 smokes. At high RPM the slide will not return with the spring force alone. To make the spring strong enough to close the slide on worst case conditions the throttle effort would be unacceptable.
This is not BS. I worked for Honda in the Mid `80s and throttle effort was a real big deal on the prototypes. All the 4 Stroke ATVs with thumb throttles (single cable systems) have compound Carbs. with a butterfly downstream of the slide (Honda) or Street bike type CV carbs (Kawasaki Mohave).
Using a CV street bike carb on the WR would be difficult to find because of the throttle position sensor hook up to the CDI box. On top of that CV carb slides tend to slam shut when pounding through the whoops.
Posted December 02, 2000 - 10:46 PM
Posted December 02, 2000 - 05:57 PM
Talked to my contact with the broken wrist, and it was a no go.... besides the safety factor mentioned, it just could not be done.
Frankly, I agree with the earlier comments, both cables must be attached for safety reasons.
Give your arm and wrist time to heal, I guess by now you have probably been told to quit riding, heck, give yourself time to heal, as your arm muscles atrophied while in a cast, do some reverse wrist curls, anything to start strengthening those muscles again.. good luck.
Posted December 02, 2000 - 09:30 PM
Posted December 03, 2000 - 06:28 AM
Posted December 03, 2000 - 10:59 PM
About your question on the return cable. The deal is high RPM and wide open throttle the slide is surfing on the intake flow. The slide spring force is not big enough to overcome the intake flow. A slack single throttle cable can't push hard enough to help the spring close the slide. The return cable is a manual close on the slide. The surfing forces are not huge and the return cable can easily close the slide.
If you run a single throttle cable you run the risk of a stuck slide at high RPM and wide open throttle. When this happens punching the kill button will drop RPM and the spring will close the slide when intake velocity drops.
If you get creative with the thumb throttle and somehow build in a kill button you will be covered.
Posted December 03, 2000 - 11:12 AM
Posted December 04, 2000 - 04:17 PM
You are seeking a solution to a very difficult problem. The push pull cable system is the cheapest mass prodution solution the factory can come up with. Adding any extra spring any where on the throttle or slide will make the throttle effort higher. Your only choice maybe to build yourself a push/pull thumb throttle.
The Honda ATC 350X had a single cable throttle system that might be adaptable for a push pull cable set up with some creative thinking.
Posted December 04, 2000 - 04:40 PM
Posted December 04, 2000 - 04:43 PM
Try the EKP needle or EKN for dunes. This needle has a steeper taper and delivers more fuel earlier. It takes less wrist movement for acceleration. It will be much like a quick throttle, but will still be the stock spring tension.
I know its not going be as good for you as a thumb throttle, but it might be worth considering.
Posted December 04, 2000 - 04:49 PM
Posted December 16, 2007 - 08:48 PM
Posted December 16, 2007 - 09:51 PM
Note: I'll not be responsible for my stupid comment if you decide to try this on your own.
Posted December 16, 2007 - 10:22 PM
Posted December 16, 2007 - 11:36 PM
Cheers from Oz
Posted December 17, 2007 - 03:55 AM