Re: New Member's 73 cb750 Café Build
I really wanted to use an internal throttle on my current build. Several of my Harley's have them and I really like the hidden single cable route. I'm pretty familiar with most units but they all seem to be made for 1" bars. Scouring this and other boards really doesn't turn up much information about units made for 7/8" bars. I did find one made by Posh in Japan and is carried by Matt Hotch in the US but we're looking at almost $400 when it arrived at my door, so I kept searching.
The name that kept popping up was one by Xoprodox and they offered ones for both 1" and 7/8" bars. Unfortunately the company has now closed but I contacted them about remaining inventory and was told they had one in stock for 7/8" bars for just over $200 so I bought it.
I can tell you that this is one of those areas where money spent is well spent. There are 1" units that you can get for under $100 but they have crappy roller bearings, stick wide open, require funny fabrication to install and generally break down or jam after a short period of use. The Xoporodox (actually Streamline Design) throttle was interesting because it had a very strong built-in return spring, sat far up in the bar and didn't require welding. Instead it used a pair of friction clips to grip within the bar so removal at a later date would be a breeze.
My handlebars are actually 7/8" Vortex clip-ons: The throttle arrives:
The first thing I notice is that there is no way this is going to slide into the thick wall aluminum tubes of the clip-ons:
I also compare the unit with a set of stock 7/8 Honda bars and can see it won't fit into those either:
Then I compare/fit to it a set of 1" Harley bars and it's clear I have a 1" throttle unit, not one designed for 7/8" bars:
Phone calls and emails confirm what I already know but trying to deal with a closed company won't solve my problem, especially since it seems Streamline Design actually doesn't make a 7/8" internal throttle. The 1" was simply marketed as being able to fit certain 7/8" applications.
To problem solve, I measure the outside diameter of the piece that slides into the bar, then head off to my local metal supermarket. Miraculously, I find some 7/8" stainless thin wall tubing with an id of 0.03" larger than the throttle sleeve. I buy a couple of feet ($16) and cut them to match the clip-on bar length:
Installation first calls for cutting 4.75" off the bar you want to install it on:
And it slides right in to match the length of the left hand bar:
Something I also noticed was that the diameter of the out sleeve was 1" which is the same outer diamater as a standard 7/8" EMGO throttle sleeve (1"):
So now I know I can get a standard set of 7/8" grips and each one will fit my bars, the left grip over the bare metal and the right which would normally slip over a 1" throttle sleeve. Here's the setup:
Pretty stoked. I know there has been lots of discussion about using two vs on cable on a four carb setup but I'm very confident that the single cable and the heavy return spring on the Keihin 29s I have will work just fine. Just in case, though, there is a kill switch just beside the throttle.
