81kz750 ltd

ok the bike is an 81 kz750h3ltd and after installing the carbs from cleaning them and backing the air screws 2 full turns upon starting now the bike shoots up to 5-6 grand and staying there i dont know what to do..i have to kill it cause it wont come dwn on rpm...all stock bike new plugs wires ignition coils

rosko77 wrote: ok the bike is an 81 kz750h3ltd and after installing the carbs from cleaning them and backing the air screws 2 full turns upon starting now the bike shoots up to 5-6 grand and staying there i dont know what to do..i have to kill it cause it wont come dwn on rpm...all stock bike new plugs wires ignition coils

Is the choke on?

And for whatever it is worth, when I cleaned and rebuilt my carbs a few weeks ago I turned them out 2.25 turns

Some common causes are----

The carbs were not properly adjusted before installation
-- bench synch the throttles and preliminary float adjustment.

The throttles are hanging open
-- twist grip is dirty or damaged
-- throttle cables are damaged, dirty or kinked
-- return spring is missing or broken
-- throttle shaft is damaged

There is a serious air leak
-- the carbs are not fully seated in the carb holders
-- the carb holders are old, cracked and leaking

The ignition advancer is stuck
-- rust and lack of lubrication

Have you tried turning down the idle control knob? Ed

ok thx for the info the main idle knob was way out ..it calmed way down idles smooth but the carbs pop with the smog pulser off the bike ..i made 2 machined plates for the reed valve covers..it was almost like the carbs were back flowing and exhaust was coming thru the vent hole on the carbs causing the bike to pulse like it wants to shut off when warmed up..so i put the smog pumper back on and it seemed to run fine except wanting to shut off..i cant bring the bike to 1100 rpm without it wanting to die...i have the air screws out 2 full turns...when looking at the rectifier wires is it the bundle im looking at for checking or the 3 loose ones coming off the rectifier wire bundle after the main pack..my manual says white/red wire and yellow and black..for the bundle of 3 loose wires i have a red/green a black/yellow and an igly yellow ..all push in connector..im confused..help..now im new to tuning carbs when adjusting the air needle which carbs do i start with?and how will i know if im turning the screws [properly?

it was the main idle knob i backed it off and it idled smooth..thx..ok thx for the info the main idle knob was way out ..it calmed way down idles smooth but the carbs pop with the smog pulser off the bike ..i made 2 machined plates for the reed valve covers..it was almost like the carbs were back flowing and exhaust was coming thru the vent hole on the carbs causing the bike to pulse like it wants to shut off when warmed up..so i put the smog pumper back on and it seemed to run fine except wanting to shut off..i cant bring the bike to 1100 rpm without it wanting to die...i have the air screws out 2 full turns...when looking at the rectifier wires is it the bundle im looking at for checking or the 3 loose ones coming off the rectifier wire bundle after the main pack..my manual says white/red wire and yellow and black..for the bundle of 3 loose wires i have a red/green a black/yellow and an igly yellow ..all push in connector..im confused..help..now im new to tuning carbs when adjusting the air needle which carbs do i start with?and how will i know if im turning the screws [properly?

i turned the knob and presto it come dwn..yaaay...thx

do i need carb caps for the air holes?

If you are asking about the vacuum barbs, then yes. Three of them should be capped and one should have a hose connected to the fuel valve (petcock) on the fuel tank.

Do you have a factory service manual? If not, you really need to get one. Check under the Articles tab on this forum to see if the one you need is there.

If you eliminate the polution system, you need to cap the vaccum carb ports.
By the way, KZ750ltd has Keihin CV34 carbs. The screw is a fuel screw, not air. it should 2.5 turns out as the service manual recalls.

ok thx...im gonna get some caps for the carbs...i have a service manual as well ..ill let yinz know how it turns out thx for the info

undiablo wrote: If you eliminate the polution system, you need to cap the vaccum carb ports.
By the way, KZ750ltd has Keihin CV34 carbs. The screw is a fuel screw, not air. it should 2.5 turns out as the service manual recalls.

Yes, my previous post was based on the completely unfounded assumption that the clean air system had been removed. If it is still in place, two of the vacuum ports will be connected to it, and only one will be capped. Be sure to use high quality caps as the cheap ones will dry out and begin to leak rather quickly. The factory ones are really good.