83 KZ750 shaft carb woes

Hey guys! Hoping to get some direction with this damned problem. My bike is stalling out on tip in and won't rev past 6k. Recently I have had the engine completely torn down to reseal the cases and such. I got all new gaskets, lapped the valves, verified that is has minimal leakdown and good compression in all cylinders, set valve clearances after bolting down the head. It has new intake boots, NO vaccuum leaks (checked with propane while running), factory airbox, and an old kerker 4-1 pipe and header.

It did not have this problem before the teardown. It did however have the factory header that the PO had hacked off the mufflers and put straight turnouts on. The Kerker I put on is baffled(sounds nice!). I did have the carbs apart before tearing it down, it ran fine after that as well. Just not after putting it back together!

I can nurse the throttle and rev it up but it wont go past 6k, almost acts like its fuel starved. If I try to goose the throttle, it dies. It does seem to be running pretty rich at idle and I saw a small blue flame out the tailpipe once while revving it. It has Keihin CVK34's, I don't know main jet size, pilots are all 35's. I have been through these things 4 or 5 times and they are CLEAN. Float level is a little high. Timing advancer is working good as far as I know. Good spark. Its running off a fully charged good car battery right now.

I bow to you Kawi Gods. Any advice or thoughts? Sorry for writing a novel on this thing...

Well, it deffinately sounds like its in your carbs/jetting if you've gone thru the motor so efficiently.

Get your float levels correct using the clear tube fuel height method, and that will deffinately help things.

After floats are set PERFECTLY , adjust your mixture screws to find highest idle.
This can be very hard to do by ear, and is usually done with an accurate tachometer, or vacuum guage.
If highest idle is more than 3 turns out, or less than 1 turn in, you will need to change your pilot jets.

Try this and let us know...

Good luck!

When you say "find the highest idle", do you mean adjust one at a time and see where the idle changes? Or adjust all of them about 1/4 to 1/2 turn at a time, to see where the idle changes?

wrangler615 wrote:

...If I try to goose the throttle, it dies...Timing advancer is working good as far as I know....

If not already done, would use strobe-type timing light to observe advancer quickly moving back and forth while varying rpm by blipping throttle.

Am thinking advancer might possibly be stuck in idle position.

Good Luck!

Would also assure there's nothing under the seat blocking intake at factory air box. (Such as a shop rag.) And that the air filter is clean and clear.

Good Luck!

One question comes to mind in reviewing your posting....
Before doing ANY carb adjustments....

Install your original exhaust system...
Does the 6Krpm max problem still exist?

If yes, then most liekly not your carb but possibly something you did in your tear down and rebuild...

NOTE: I said most likely....

Just a thought....


OMR

OMR- unfortunately I no longer have that exhaust. It hit the scrap barrel the day after I got my Kerker. But it was in very hacked condition, and I'm sure couldn't be the cause of this issue.

Patton- I do have a clear airway, and the vacuum slides are working perfectly. I will double check the timing components just in case...

It's one thing to not be able to goose the throttle, but I need to be able to get it up into the 5-8k range for highway cruising. I'm just not sure what could be causing this "rev limiting".

Got the carb float levels adjusted... we'll see if that helps when I have time to put them on. I checked on my jetting. The mains are stamped "100" and the pilots are stampe "35". I thought this seems lean for the mains, but it ran good last time it ran on the street(2 yrs) at my altitude(~6000'). Thoughts???