Trouble Starting When Warm

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Sep 7, 2006
My 1972 Fastback had developed an annoying habit of being difficult to start when it is warm. By this I mean it starts fine stone cold (first or second kick) and re-starts fine if you stop and start up again within a few minutes. Trouble only arises if you stop, let it cool for 30 minutes or so, and then go to re-start. Bike has a single 34mm Mikuni and Boyer Ignition.

Bike always started first or second kick at any time. Clearned all wiring connections and checked for spark, which check out. Seems to be getting fuel, plugs are moist and there is fuel in the line and bowl. When I go to re-start if has cooled down somewhat, I give it some choke, and it the past no problem. It will push start when these problems arise, so it appears to me this is not a coil issue and the battery is new. If anyone has had simiilar problems and has cured them, I would be interested in learning the solution, before I tear into carbs. Thanks
Moist plugs can mean one of two things lost spark or too rich.
Have you first tried starting without the choke, or when it won't start with the ignition off giving it a few kicks with the throttle fully open?
Does adjusting the air screw slightly (in or out) make any difference?
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