BACKFIRE
 

Some times from starting from cold,driving at low revs,I get a backfire which comes all the way out through the airbox.the engine misses as a result and sometimes stalls in the worst kinds of situation.My plug only has 1000 miles on it.What could be the possible causes?
Otherwise it's running ok.

seems that something is wrong with the ignition.
check pickup-coil and cdi-unit.
in the worst case you need a new (second-hand) cdi-unit. try first to change the pickup / cdi-unit with somebody else.
regards
klaus

I think i found the backfire problem.The inlet rubber for the primary carb was in two pieces,drawing lots of false air.I also stripped the carbs and cleaned.Everything seems to be ok now except for an accasional lag when I shut off the throttle,not a lot but it doesn't shut off completly.Like a little bit of over run.In the exploded drawing of the carbs on the link from this forum,the assembly no.42?What is this and what will adjusting it mean?I have the Clymer manual but I can't see a corresponding screw.

congratulations!
strange that the problem occured only sometimes.
ass. 42 is the idle run adjustment screw (hope you know what i mean). it's located here: http://www.xt600.de/xt_werkstatt/+sp...euse_unten.jpg
(no. 12 in picture).
look also here: http://www.xt600.de/xt_werkstatt/+sp...uesen_assy.jpg (no. 31).
turn the screw in -> lean mixture
turn the screw out -> rich mixture
look here: http://www.xt600.de/xt_werkstatt/+sp...rim_schema.jpg

regards
klaus

forgot:
basic setting is 2 1/2 ... 3 revs out (depending on modell and when everything else is o.k.).
klaus