1983 XJ 550 Throttle Shaft Bushing Sizes???

Greetings,

I have been restoring several Viragos and one Xj550 Maxim over the summer. I have got to the point to where the bike fires and runs great EXCEPT the carbs aren't popping back to where they should when going back to idle. I have cleaned the carbs very well inside and out and replaced the throttle stop springs and it still isn't snapping back to idle. (I do not believe that the cable is the issue because if I press on where the throttle stop springs are just a little bit with a screwdriver, then it returns right back to where it should be idling. Also, there is some play in the throttle shaft of one of the carbs. So, I was debating on changing out the throttle shaft bushings in order to get rid of the slop and hopefully assist the bike returning all the way back down to idle consistently after the throttle has been let go. From doing some research, it seems as if the carbs of choice on this bike is the Mikuni BS 28 series. Does anyone know the PN or sizes of these bushings?

 

BTW.. I had a way more detailed post but it kept saying that it couldn't post it because of "spam like" stuff in it (I even took out the xj4ever links and it still did it)

 

I've never heard of that issue. Are you sure it's the butterflys and not the slides that are slow to return? You might be better off trying to find another set of BS28s. Dave Hogfiddles will b along soon to advise more..

 

The slides are vacuum-operated, it's probably not what you think.

Sounds to me like carbs not properly set up. Hanging idle is generally due to an out of sync condition which can be exacerbated by out of spec valve clearances and/or improper float levels. It's rarely binding throttle shaft bushings.

Any binding in the rack should be able to be dealt with in the course of your bench sync.

Have you: got the valve clearances in spec? Fully serviced the carbs, including wet-setting the float levels? Mikunis very fussy about this. Done an accurate bench sync? Running vacuum sync, with YICS blocked?

The above steps, in order, are required to properly set up the carbs. It sounds to me like you may have missed a step or two...

 

Also make sure that the throttle plates are centered in the bores. It's really easy when reinstalling them to have one or two be slightly off, and then they'll bind when the linkage closes them. Loosen the screws up just enough for the plates to move, and snap the throttle closed a few times to center them, then retighten.