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A new type of throttle "waterproof"!


10 kW
Apr 25, 2007
Hi all

this is the start of a thread on how I got round the problem of putting a throttle on a kmx where for me the thumb throttle supplied or a twist grip throttle.
I used in the end an adaptation of the throttle used on an old ZAPPY Turbo I have, this had a twist throttle on the handlebars with a cycle cable going from it to the battery box not electrical cable.During an investigation of the setup I found it went into a small screw top box with a electrical wire coming out connected to the speed controller.
I opened up the box and found it consisted of nothing more than a slide pot and a spring, so any method of pulling a cable could potentaly be used as a speed controller so any gear shifter that could be altered to be free turning friction or click shifting removed, with that knowlege I got a bar end shifter used on recumbents alot until resentally. I took the thing apart and worked out how to make it free running, I then made a copy of the zappy throttle box and used it in the kmx.

I have since thought that this method could be universal and on reading Deecanios thread on the DC1 his new creation and several people commenting on throttles going wrong in heavy rain due to the electronics being difficult to make waterproof on the handlebars. My idea is to move the electronics away from the handlebars and into somwhere less exposed this little black box of mine has done this so far for me on my KMX which I use in all weathers.

The KMX was resently stolen and recovered, the KMX was dammaged minorly and the black box was stolen I have just finished making up another throttle black box.

Basic list of conponents:-
small box
45mm 50k lin slide pot
32mm length 6mm dia expantion spring
super glue
epoxy glue
plastic for packing
small bolt to use as a anckor for the spring
1 strip of 45a ,3a screw cable joiner(get from wilkos for less than a pound)
Hi all
here is a picture list of the bits required for the throttle assembly.


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Hi all
below is a picture of everything put together all that is required attach the throttle wires to the right wires on the pot then glue the pot into place with epoxy also covering the pot's terminals for added strength.
Next a gear shifter is required with the click removed see future posts for how to do this.


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That's a great idea geoff. I wish the controller manufacturers would make a controller with a cable attachment like that. It sems like your idea could be easily built into the controller.

Hi all
I've found two types of twist grip avalible, in one the cable goes half round the grip or so, in the other the cable loops around the grip one and a half times, see pic below. You will find the type where the cable loops round the grip won't work. A way to find out is to ask the cycle shop how the cable is replaced, if he does not know it should be on the mantence sheet with the shifter. If you have no luck there look at the shifter as a rule of thumb if the cable is thredded from the part that fixes on to the handlebar then it is a loop sort , if the cable threads through the grip it should be a half loop and should work. see the exploaded pics below.
Hi all
here is a step by step guide on how to convert a twist shifter into a twist throttle.


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