rough ridin 81 kz750

hey guys.. new to the forums and hope someone can help me out. My 81 KZ750 runs pretty well most of the time but lately it's been doing something strange.

after riding for 10 minutes or so with the engine all warmed up and the choke fully off, the engine will nearly stall on me and I have to wring it's neck/throttle to keep it alive. this will last for a minute or two and then usually goes away.

I'm thinking it's the carbs but before I spend the $$ to rebuild them I'd love to know if its something more serious that would put the bike in the "too far gone" category.

any thoughts would be greatly appreciated.

thanks

Check for vacuum leaks.

How old is the battery? Ed

.

thanks for the tips guys.. i'll give them a try

(BTW, the battery was just replaced)

question your suppose to run the bike in pri correct because if i take my tank off the bike and turn it to on or reserve it dosent have gas coming out but when it's on pri it comes flowing out pri is primary correct sorry i'm new to this and i just seen you said try runing the bike on pri in a post and i thought that's what your suppose to run it in.

Vacuum operated petcock receives vacuum from a running engine via a nipple fitting on the carb or carb holder from which fitting a vacuum hose runs to the petcock.

When there's no vacuum being supplied by a running engine, there's a rubber diaphragm, o-ring and spring inside the petcock that prevents fuel flow in the ON or RES (reserve) position. When the engine isn't running, both ON and RES positions are the same as OFF. This design allows us retards to ignore any need to shut off the petcock when parking the bike.

PRI (prime) position by-passes the rubber diaphragm, o-ring and spring, permitting fuel flow without needing any vacuum. Same as a manual (non-vacuum) petcock in ON or RES position. For example, PRI could be used to fill the carb float bowls when the engine isn't running (i.e., when there's no vacuum being supplied to the petcock).

Good Fortune!

if you leave it on prime without the bike running it will flood the engine