Help!! Kz750 LTD! Newbie...engine studdering

[Bigphil001]

I just bought a 1980 KZ750 as a project, and After it warms up, and you take the choke all the way down, the engine studders when trying to start up from a stop. It will simply not accelrate with any briskness until it gets above 2500 rpms, at which point it takes off. I can ride it with the choke on, and it idling at like 3000 rpms, but thats just not right. Could someone please help me figure this out, I think it could be the carbeurators but I'm really not sure. any help would be apprectiated.

[78_KZ750_Cafe]

Carbs need a cleaning, probably jets. What color are the spark plugs?

[RomSpaceKnight]

What mods or state of repair is bike in. Sounds like it is lean. Choke enrichens. Probably dirty carbs. A part of the idle system. Stock airbox, carbs and pipe? Could be out of synch.

[Bigphil001]

I got it from a guy who said it sat for aobut a year, so it oculd very well be the dirty carbs. Everything appears to be stock on the bike, no modifications whatsoever. You think the first thing to try would to pull the carbs and rebuild them?

[Chevy]

Originally Posted by Bigphil001

You think the first thing to try would to pull the carbs and rebuild them?

That'd be my first choice. It sounds to me like the primary jet in either your no.3 or (more likely) no.4 carb is plugged. The Keihins have both a primary jet and a secondary jet. Once you get past a certain RPM the secondary jet will "mask" the problem with the primary jet to a certain extent.

Does it seem to backfire/pop on the right side either through the exhaust or the intake? My poor Spectre was doing that and it turns out that the no.3 AND the no.4 carbs were gummed up big time. Even the secondaries were clogged. Of course it spent 6 years sitting on it's side stand before I got it...

[Bigphil001]

Actually it does do exactly that, I will take a look at the carbs tommorow, and see if they need cleaning.