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Discussion Starter #1
It might be an obvious answer, but I'm new to the motorcycle world, and I don't know what to search for. I have a Suzuki GS400 from '79 and the yokes on that thing are hideous. So my question is; do triple trees and yokes have specific measurements I can use to find matching triple trees and yokes? Or can I look up motorcycles that use yokes with the same measurements as my bike?

Thanks in advance :)
 

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Do triple trees and yokes have specific measurements? Yes, many of them and it is not easy to mix and match the triple trees from one motorcycle to another. Their shape and dimension can affect changes in the way the bike handles and in the bikes turning radius if you depart from the original dimensions. Triple trees can be custom built from scratch if you are a very good machinist and have the $ as well as a facility to machine aluminum with great precision. It can also be a good place to add strength to the front fork assembly, or reduce the bikes weight by as much as several ounces.

True story: My father-in-law once welded up a top triple tree for a Yamaha RD200, entirely out of scrap steel plate and pieces of pipe, using only an angle grinder, drill press and a stick welder! It looked like crap but it worked and it did facilitate an economical and much needed repair to the bike.

If you are going to search for substitute parts from other motorcycles at a wrecking yard, the best way to start would be to remove both the top and bottom yokes along with the steering stem as a complete assembly. Take an accurate measure of the front fork stanchions in millimetres (they will usually measure out to an accurate even mm number) I'm going to guess 33mm based on this post:
http://www.caferacer.net/forum/project-builds/14059-triple-tree-fork-conversion-chart.html Then start your extensive search of what might be available in Denmark.

You say your existing yokes are hideous :/ that sounds like they are not broken but you want to affect a change only in their appearance. That is kind of a strange reason to start changing parts out on a motorcycle that many would consider to be constructed with uninspiring components. We are talking about one of these, yes?



I can hardly see the triple trees from here and the bottom one is even covered with a trim plate. What are you trying to achieve with your changes to the bike that would have you start by changing out castings ? (the most expensive and unique parts on a motorcycle are the castings)

 

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You can also modify your existing yokes as I did on my Yamaha R5. When I switched to clip-ons I filled the existing handlebar mounts with epoxy and smoothed everything down with a grinder & file. I also got rid of the ignition switch and tachometer and cut a central mount for the speedometer from aluminum. Ignition is now by on/off switch.
Jim B email triple 1.jpg email triple 3.jpg
 

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This guy has way too much time on his hands and is working with somebody else's money and equipment:



lol must have had a real bad experience with stanchions sliding up in the triple trees.
 

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Discussion Starter #6

I can hardly see the triple trees from here and the bottom one is even covered with a trim plate. What are you trying to achieve with your changes to the bike that would have you start by changing out castings ? (the most expensive and unique parts on a motorcycle are the castings)
I've bought clip-ons, and the top yoke is cast to hold a handlebar on top, which makes it look bad, when there's no handlebar to hold. I just want a simple, flat top yoke, but it's also hollow, so I can't even grind it off.
 

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Discussion Starter #8

If you are going to search for substitute parts from other motorcycles at a wrecking yard, the best way to start would be to remove both the top and bottom yokes along with the steering stem as a complete assembly. Take an accurate measure of the front fork stanchions in millimetres (they will usually measure out to an accurate even mm number) I'm going to guess 33mm based on this post: http://www.caferacer.net/forum/project-builds/14059-triple-tree-fork-conversion-chart.html Then start your extensive search of what might be available in Denmark.
But surely the measurements of the stanchions' thickness isn't enough? What about the spacing between the two, as well as that third axis?
 

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You can also modify your existing yokes as I did on my Yamaha R5. When I switched to clip-ons I filled the existing handlebar mounts with epoxy and smoothed everything down with a grinder & file. I also got rid of the ignition switch and tachometer and cut a central mount for the speedometer from aluminum. Ignition is now by on/off switch.
Jim B View attachment 18064
Those two holes left by the handle bar removal make great places to put the tiedown hooks on vintage racing RD's
 
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