Hi…my name is Mario James. I’ve been on this list from the 1990s, on and off. From Jamaica. I think your problem Roger might lie in the throttle shaft bushings leaking air. They are notorious for doing that, and difficult to diagnose if you don’t know what to look for. I am assuming of course that the carburettors are not new, and have quite a few miles on them. Pressing out the old bushings and getting new ones made should be straightforward for a machine shop. Get the new bushings made out of Teflon. Some people use brass but that’s a mistake as the throttle shafts are made of the same material, and they wear out in no time. Bronze may last longer but u would still need to make a provision for oiling and where the bushings are I don’t see how that would be possible. Teflon lasts and lasts and lasts, I think some kind of plastic bushing was factory installed when new.
Wiggle the throttle shafts on the carburettor that u suspect. Heck, do both. If you find play that you can feel, replace them.
Also when you back off the mixture adjusting screw all the way with the carb piston removed, does the jet come all the way flush to the bridge, even protrude slightly? If it doesn’t that’s a problem too…Sent from my BlackBerry 10 smartphone.
The archives and FAQ will answer many queries on the XJ series…
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