INTERNAL THROTTLE

After searching the internet for internal throttle's and seeing that the average price was between $130. & $199. US dollars,after converting the Yank dollar to Aussie dollars around $250. - $380. I decided bugger buying one I would build my own. Plus buying one defeats the purpose of hand fabricating a Chopper. After making that decision i searched the net for a "how to", thinking that someone else must have done it and put it on a site. I spent two days searching the net and found nothing. So i had a look at some of the commercial units,the picture to the right is one of them.I reckon it didn't look to complex and set about building one.

What a joy that turned out to be....Seriously it was good fun. It's amazing what a little time and ingenuity can produce. First thing I did was measure the internal diameter of my handle bars,they were 23.6 millimetres (hereafter referred to as mm),so that gives me my external diameter of the internal throttle body.

The next step was to draw the whole thing up on paper which is the image on the right. I will add the dimensions of all the bits further down the page.Next came chasing down the materials, then deciding how i could make all this with basic handtools. As i don't own a machine shop this was important that i could make it using handtools that everyone should own.That makes this achievable by everyone.

The tools you will need are:

The image to the right is me making the slot in the throttle body, Take your time be patient and it is achievable. This took me about 25 minutes to do.

this image is the drill press fitted with a de-burring tool. It doubles as a drill bit and is ideal for forming a slot in the throttle body as the photo shows.You also need a mini vice to hold the body. I drilled a pilot hole first then used the tool to enlarge the hole, then slowly moved it down the body until I had the length i wanted. Because i didn't have a 2 way vice I used my left hand to move the vice along whilst holding the drill lever with my right hand.As I said earlier take your time and be patient, anything can be achieved.

This photo is of the finished throttle tube the slide and pin, next lot of photo's will be of the slide actuator and the measurements to make your own.