83 KZ750 shaft keihin pilots?

Can't remember off the top of my head the exact numbers but I do remember they were all within 7-10 psi of each other

I am going to try to get some videos of the bike running rough. I will get some when it's cold started, warm, then after riding it for a while. Anything specific you want me to show in the videos? I wont be able to make them until wednesday at the earliest, maybe not even til next sunday. The weather here is not looking nice enough to ride until then.

rboutin2 wrote: ...stumbles and is running lean on the low end, anything below 2700-3000 rpms....

Is a classic symptom of blockage in the pilot circuit.

Would double-check that carb spray squirted into the pilot jet exits from both orifices into the carb bore.



Some CV carb designs have the orifices located through top of the bore, and in any event the orifices are usually located near pointed tip of the the pilot screw.

If an in-line fuel filter isn't fitted, or the float bowl contains grit or sediment, a perfectly clean pilot circuit may instantly again become blocked.




Good Fortune!

I can say 100% for sure that the pilot circuit is free and clean. i've been through it many times, triple checking everything. fluid and air both come out of where they are supposed to. Even the 3 little holes above the throttle plates are even clear.I can geta steady stream of carb spray through them no problem. This is the whole reason why this is such a weird ordeal i am in. The carbs are spotless, all jets are the right sizes for stock, the air filter is new and correct for stock, there are new boots on both sides of the carbs, the valves are in spec, timing advance is correct, never have run ethanol since the carbs were cleaned. new pilot o rings. Float heights set. etc etc. Yet, the problem still persists.

Are spark plugs the brand and heat range as provided in the FSM (and especially not a "hotter" plug) ?

Good Fortune!

yep. I put in exactly what the manual states. They are NGk B8ES.

Has strobe type timing light even been used to assure proper functioning of the automatic timing advancer?

Has the reported stumble always existed during your experience with this bike?

Good Fortune!

If not already tried, would fabricate and install some baffling in both mufflers to add some back pressure, and test run to see whether the same stumble occurs.

Good Fortune!

I have not checked it with a timing light yet, but everything does move freely. My dad can't find his timing light. So I am not 100% sure that the timing is working perfect, But nothing is stuck, and the advancer does move freely and you can see it move as the rpms go up. Also, I had thought about repacking the mufflers. Any suggestions on what to use? I have an 82 kz650 h2 I could swap pipes from temporarily. Would they fit on my 83 kz750 f1?

from left to right on the bike when you're sitting on it, the compression readings are:
1- 143 psi
2- 137 psi
3-137 psi
4- 145 psi

I also checked the timing with a strobe timing light, and it is advancing properly, and the timing is correct.

Any news?