souring VM24 #16 pilot jets?

I recently swapped carbs on a kz650 from the VM22 to VM24. big improvement in fueling but it was getting this weird surging cruising at highway speeds and also during off-idle acceleration. I changed the pilot from #15 to #17.5 and the surging went away and overall performance was improved except  now it is too rich at idle and can be difficult to start compared to the #15 pilot. I was consulting the service manual and I saw that the original pilot jet size is listed as #16. which seems like it would be the perfect balance, however i cannot find this size of jet anywhere.

any ideas?

 

I think that those and 100 mains were for US emissions on 22's. In the uk the standard jets in 24's is 15's an 102.5's.
Bets are off if you have non stock exhaust and air supply.
Also as you have founds mikuni jets go up in 2.5's so 16 is a misprint or a special. Never seen any and I have striped plenty of US import 22's.

if your carbs have a pilot air screw, I'd open them some more and see how the bike responds.  

I have always thought that table in the B1 manual is a misprint, but I have no data to back it up other than other lists in later manuals, and the fact I have never seen a 16 pilot jet offered by Mikuni,  

 

wrote:

I recently swapped carbs on a kz650 from the VM22 to VM24. big improvement in fueling but it was getting this weird surging cruising at highway speeds and also during off-idle acceleration. I changed the pilot from #15 to #17.5 and the surging went away and overall performance was improved except  now it is too rich at idle and can be difficult to start compared to the #15 pilot. I was consulting the service manual and I saw that the original pilot jet size is listed as #16. which seems like it would be the perfect balance, however i cannot find this size of jet anywhere.

any ideas?

 

Hi Doc, I haven't read the other comments yet but, I had this exact same thing with my sons bike, fully rebuilt VM24's, 100% spotless, the bike "hunted" at highway speeds, A hesitation/ surge , I raised the needle one position and the problem went away immediately, haven't touched the carbs since....

Another thing to remember is todays fuel is not the same as when these bikes were new and I'm not even referring to the ethanol.


.

wrote:

I have always thought that table in the B1 manual is a misprint, but I have no data to back it up other than other lists in later manuals, and the fact I have never seen a 16 pilot jet offered by Mikuni,  



 

When you are a big OEM like Kawasaki, Mikuni will customize jets for them.  Like the 2.3 float valves used on the big bikes.  That said, I suspect you are correct in that the 16 is a typo.  The parts fishe references #15 pilot jets.

well back to #15s then. i will try raising the needle next.