VM24 650cc - Pilot screw posistion

Good day,

Can someone tell me what stock pilot screw posistion is for 650CC with VM24 carbs?

I'm not familiar with the 650 D4. Do the carbs have a pilot fuel screw or a pilot air screw?

Typically pilot fuel screws are set at 3/4 - 7/8 of one turn open. More open means richer.
Pilot air screws are typically set at 1-1/4 - 1-1/2 turns open. More open means leaner.

In both cases the pilot screw affects idle and up to about 1/8 throttle or so. When syncing it's customary to tweak these screws until you achieve the highest idle speed and good tip-in performance.

Depending upon upon where the bike was originally sold (US market or elsewhere) there will be differences. In the US market they came stock with and accelerator pump and in other markets came without the accelerator pump. Both came stock with pilot air screws, but there are differences between the main jets, needle jets, needles and slide cutaways between the 2.

Though I do not have a table for the D4 I have attached several tables for FSMs for the different years models that show the settings

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Wow thank you !

I have been advise to back to stock setup on the carbs except main jet, and take it from there.

Orginal the big was 1981 KZ650-D4 (The SR series of KZ650 was internally known as the Kawasaki KZ650D.), but the engine have been replaced with a 750-H(X) Ltd 81 H1 as 1980 and H2 was 1981 (don`t know witch).

The carbs have not acc. pump.

I will set the scre to 1-1/4 - 1-1/2 turns open as Nessism mention for Pilot air screws.

I guess these is the correct setup when it was orginal ?

There should be an ID stamped on the carb one either the flange below the choke lever or on the outside of carb # 4 (same location on flange see pic) If you post what the ID is then I may be able to tell you more about what model / year they came stock on and what the internals were.

Some great information in this thread as related to the original carbs specs. Realize though that the original specs represent a carb that's been tuned to an emission spec, not for best running.

Agree Ed, not only are they tuned for specific emission the stuff we call gas now is much different than it was when these bikes were new. I was just trying to give the OP some info to work with.

Did not bring up fact the 24ss carbs may be a bit small for the 810 he is running and that the stock jetting etc for a 650 will require differences to work with the larger motor.

gd4now wrote: Agree Ed, not only are they tuned for specific emission the stuff we call gas now is much different than it was when these bikes were new. I was just trying to give the OP some info to work with.

Did not bring up fact the 24ss carbs may be a bit small for the 810 he is running and that the stock jetting etc for a 650 will require differences to work with the larger motor.

Thank you for all info

When it come sto jetting around my engine and the carbs can you see here:
kzrider.com/forum/3-carburetor/615349-810cc-and-vm24-jetting

I have been advise to go back to stock pilot and stock needle posistion and I trusts zed1015 skills
The main jet will be set larger.

So I wonder just where the starting point for the screw should be, and I will start with 1-1/4 - 1-1/2 turns open from what I have understood from these threads.

My understanding from zed1015 is that 15 pilot jet shall be okay with 810cc and VM24 from 650cc engine, if I need some more gas, I should be able to compensate with the screw, so it turns down to find correct main jets.