how to install carb and adjust throttle linkage

I'm putting a 36 mikuni pumper on an XR 400. I am so old school, I have never even seen dual-cable carbs! Just used to unscrew the top and pull out the slide and needle.

So, #1, it's really tight in the carb area. #2, seems like I gotta undo the cables to get the carb out, and #3, I can't see quite how to get enough slack to undo the cable ends from their retaining holes.

Then, supposing I get the old, stock carb off, is there a proper sequence for running and adjusting the two new cables?

Any tips or leads to a thread would be greatly appreciated. The carb came without any instructions.

Did you get new cables with the pumper, or are you using the stock Keihin ones?

AFAIK, the cable lengths outside the cable housings should be shorter for the pumper. When I got my bike, already fitted with the Mikuni, only the stock "pull" cable was installed, but as it's too long for the pumper it was put into the further-away "push" position. It worked great, but after some time I made 2 new cables with the correct lengths.


For fitting, I would advise to first install at the carb end, then at the grip end.

It did come with cables. I've discovered they need to be mounted in the "short" cable positions on the carb. I am struggling at the moment to make them fit on the throttle assy: there doesn't seem to be enough slack in the return cable - I've shortened the adjusters at both ends.

I'm still fiddling. I might just go with the "pull" cable if necessary.

Take the seat off so you can see down from the top. To get the cables unhooked from the stock carb there's a screw that mounts the cable holder to the carb. Take that screw out. Then turn the handlebars to the left to get slack and pull the cable holder with cables attached toward the rear of the bike. That will give you enough slack to run a long thin screwdriver up under the cable and to the cable end and slide it out of the hole of the throttle cam.

When you install the Mikuni, attach the carb end of the cables to the carb first. The pull cable goes at the bottom of the throttle cam and the push goes at the top, in the holes closest to the front of the carb. Run the cable adjusters at the carb bracket all the way to the rear for as much slack as possible for when hooking up the throttle end.

The Mikuni isn't as easy to install or remove as the stock carb is because of the way the cable holder bracket at the carb is mounted.

If you find it difficult to hook up the throttle end of the cables, I've found that removing the the throttle assembly from the handlebars, connecting the ends, then sliding the assembly back on the bar works well. After it's all hooked up it's just a matter of taking out excess slack at all the barrel adjusters. I set the ends at the carb in the middle of their range to begin with, then adjust the throttle ends. Fine tune slack until you have the amount of throttle play/slack in the system that you prefer.

It is not recommend to run only a one cable setup on the XR. That other cable is there to pull the slide closed against the high side pressures the carb slide sees, typical of a 4 stroke engine.

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