slight hesitation at lower end of rpms

thanks Patton thats good info!!!Im no carb guru!

I think the 77 KZ650 models came with air screw located on the sides of the carburetors. Well, if you have adjusted your air screws to no good effect, check WHERE The clip is on your slides... put it on the 4th slot. If it is on the 4th slot, then try the #20 pilot jets someone else suggested. I have never needed to use #20s to richen up the pilot mixture... #17.5s have been enuf.

Thanks Wiredgeorge thats what I will do!By the way the adjusting screws are on the sides!Previously I meant than they were not on the bottom.I have an extra set with the screws on the bottom so I know what ya mean.Thanks again.
Tony

If problem continues unabated even after adjusting the pilot air screws to enrichen mixture (turn in clockwise to reduce air being allowed into mixture), then would consider restoring the pilot circuit to as-new condition.

Pilot Circuit Overview

Freshly filtered air goes into a small entrance hole on the airbox side of the carb. Sometimes there's an air jet, but oftentimes not. Thinking no air jet on subject carbs with side located pilot air screw -- just the simple entrance hole. Anyhow, air enters the small entrance hole and continues along a passageway until reaching the pointed tip of the pilot air adjusting screw which regulates amount of air allowed to continue thereafter on to the pilot jet.

Meanwhile the pilot jet has picked up raw fuel from the float bowl. The air reaches the end of the air passage at the pilot jet where the air joins the fuel creating an air/fuel mixture which mixture then travels from the top of the pilot jet on through the pilot passage and out the pilot outlet (a tiny orifice in bottom of carb bore), from where the mixture is sucked through the intake valve into the combustion chamber.

All this is accomplished while the throttle slides are positioned completely down with no additional mixture contributed from the needle jet. And the pilot circuit continues this function of providing fuel mixture until about 1/8th to 1/4th throttle opening position. As the throttle is opened, the slides are raised, which allows increasingly more mixture from the needle jet and lessening effect of mixture from the pilot circuit.

Now, toward achieving a perfect (as new) carb pilot circuit --- And there are undoubtedly other and perhaps better methods, maybe even far superior methods, but here's how I do it, until learning a better way.


Pilot Air Passage

The pilot air passage throughout its entire length from entrance hole at airbox side of carb throat to the pilot jet should be clear and ultra-clean.



Pilot Passage

The pilot passage from top of pilot jet to and through the pilot outlet should be clear and ultra-clean.



Pilot Jet

The pilot jet central hole and lateral holes should be clear and ultra-clean. The pilot jet itself should be in pristine condition and the proper size. Remember, possible damage from previous cleaning efforts (with wire or otherwise) may be visually imperceptible. Holes appearing perfectly round and clean may be faulty enough to disallow the absolute precision needed to properly meter fuel intake from float bowl and infusion of air from the air passage. As new pilot jets are relatively inexpensive, I prefer to replace them. Opinions may differ, but new pilot jets worked for me. And I have yet to see any visual defect in the old original pilot jets (even with some slight magnification).


Cleaning The Passages

With carb on the bench, remove float bowl, float and pilot jet. Wear protective goggles. Plug threaded area where pilot jet was removed so as to block access into float bowl (using finger is okay). If pilot air screw has been removed, block its hole with finger. Direct carb cleaner spray into air passage entrance and blast away until spray freely exits from pilot outlet.


Pilot Air Screw

Remove pilot air screw and examine pointed tip to assure it isn't damaged. Carb cleaner spray directed into the (1) pilot air screw hole has three places where it may exit, (2) Air passage entrance, (3) into float bowl through pilot jet location, (4) pilot outlet. Any two of these may be purposefully blocked so the spray flows between the other two. Spray every combination until assured all the passages are clear and clean as new.

Here's a diagram for reference. Good Luck!

[click on image to enlarge]

Did you check your points?

How about your centrifugal advance and advance timing?

wow Patton that,s over and above what I expected for help.I thank you!Im gonna pull the carbs or maybe try it on a extra set I have and let you know!Thanks Again!
Tony