High idle 78 cb550

uksparky

New Member
Bought bike been sitting two years, rebuilt the engine, new primary chain, cam chain valve job etc....rebuilt the carbs, i did the carbs before i pulled the engine but still had this problem before i pulled the engine. Idle in garage perfect 1100 rpm......now i take it for freeway ride ten miles, exit and bang its idling 3k..........turn thumbscrew bringing idle back to 1100rpm, ride around town perfect idle, back on freeway heading home and idle perfect....fire it up ten minutes later 1100 idle ok...overnight in garage morning start engine getting hot.. idle comes down and dies...so i give it a turn to bring it up.
New intake rubbers.. O rings
carbs sync
fuel level ok did clear tube test
jets cleaned 42 pilot 90 main...not drilled
sprayed carbs no Vacuum leaks
Cables ok, no binding
spark plugs all tan color
mixture screw 1.5 turns out
timing ok, electronic ignition, advance ok

It looks to me like coming down from main jet fueling to idle pilot jets there is a delay, i have the stock exhaust and air filter, but the air filter is foam lined
 
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