Justinmkantor wrote on 12/05/08 at 20:53:04:If I keep it at 1G then what dod I do about the shotgun? Is there anything else that could set it off like that? Timing, valves, unseen hole in exaust system? A gremlin that belches who live inside?
Agree with keeping the idle at 1000 rpm at a minimum.
On the VM carb, the pilot adjusting screw works
opposite of the stock carb. Stock carb screw turns out (counterclockwise) to richen mix...
on the VM carb the pilot screw turns IN (clockwise) to richen the mix. This is probably one of the primary sources of frustration for you.
The carb manual covers the tuning steps for all 3 throttle ranges.
Also, you should recheck your exhaust system. Don't just check to see if the bolts are tight, but take the muffler and header off, install a new head/header gasket and reseal the header/muffler connection and then make sure of proper alignment when the bolts are tightened.
The bolts may be tight now but with the age of the bike, if the seals/bolts have been untouched for a long period, it is possible that the seal is broken (allowing air into the system and creating backfiring) even though the bolts still seem to be tight.
Better to take a little time and redo the sytem and make sure there is no air leaking into it and causing backfiring.
There are only 2 primary causes of backfiring, the pilot circuit of the carb running lean & air getting into the exhaust system, so your solution is likely to be found in those systems.
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