28mm VM carbs

Ok, thanks for the info, I got a 20 pilot jet as of now, so I’ll look around for something bigger, partzilla only offers the 17.5. Get a bigger set and see what that will do. Have needles on the third clip.

Keyster offers up to #30 Pilot jets.

www.motorradbay.de/kys060xxx-c-207_209_2...cab37f89e1de5e9278bd

I have some 22.5's that I think I got from Z1 Enterprises. I don't think you need to go larger than that.

No eBay APP ID and/or Cert ID defined in Kunena configurationIf you are running no airbox or pods you really need air corrector jets fitting to cure the off idle flat spot and improve running.

These air corrector jets certainly look interesting. How do these actually work to improve things? And these are only for use when eliminating the air box?

Rick H.

Rick H. wrote: These air corrector jets certainly look interesting. How do these actually work to improve things? And these are only for use when eliminating the air box?

Rick H.

Yes! only for use with increased airflow when running open carbs, stacks, pods or modified/cut airbox.
The info in the listing explains it all but the quick explanation is that they restrict the air bleed to the needle jet tube and increase the signal and fuel to the off idle circuit which fills the flat spot.
This is a better and the correct fix rather than lifting the needles which only masks the issue and also over richens wide open throttle and increases fuel consumption.
With these jets you can usually drop a size on the main jet also .
If you look at the Mikuni smoothbore carbs they already have this extra adjustment from the factory ( research jet BS30/97 online ) but those jets are m4 thread. and are too small to use in the stock VM26/28MM upgrade hence these are m5 thread.

Those corrector jets look interesting. They go on the intake to the pilot circuit? Do you have to tap the pilot air intake? How do you know when the orifice is the correct diameter?

In thinking how to use the needles correctly I wonder if a double taper would do the trick...adding fuel early and restricting it in the upper half?

hardrockminer wrote: Those corrector jets look interesting. They go on the intake to the pilot circuit? Do you have to tap the pilot air intake? How do you know when the orifice is the correct diameter?

In thinking how to use the needles correctly I wonder if a double taper would do the trick...adding fuel early and restricting it in the upper half?

The info is in the listing and in my last post.
They go in the air bleed to the needle jet tube.
NOT the pilot circuit orifice which is opposite and has the air screw for mix adjustment if of that type and a fuel mix screw underneath if of the other. ( or both if Suzuki VM's )
You tap the hole M5 at 8mm deep.
The hole is already the correct size so no drilling needed.
Needle taper won't correct the flat spot as it is a low speed atmospheric pressure issue in the venturi not flow through the needle jet.
If a change of needle profile was the cure Mikuni would not have added the jet bleed facility to their smoothbores which are mainly used in non airbox performance applications.

Thanks for the info. My interest is because I have a 1980 KZ1000 LTD with VM28 carbs with a pump and I put a Z1 intake on it. I have some hesitation from a standing start and was wondering if this would cure it. Apologies for the thread hijack.

So this additional air intake jet restricts air entering the diffuser on the main jet circuit, allowing more fuel to enter the venturi at low rpm's via the main jet. Is that correct?

hardrockminer wrote: Thanks for the info. My interest is because I have a 1980 KZ1000 LTD with VM28 carbs with a pump and I put a Z1 intake on it. I have some hesitation from a standing start and was wondering if this would cure it. Apologies for the thread hijack.

To find out if it's an over rich or lean issue just feather the choke ( enrichener ) at the point of hesitation.
If the issue is resolved then you have a fueling gap but if it is made worse it's bogging due to over fueling.
Both lean and rich conditions can cause the same symptoms and this is a quick way to find out.
Beware that early z1 airboxs can be very restrictive , especially if it still has the metal brace installed in the opening which will cause the fuel/air ratio to increase.
This is possibly your problem especially coupled to the extra fuel supplied by the accel pump on initial throttle opening.

Sorry for the late reply, work been busy . Thanks for all info guys. I did find water in the gas tank I guess from the gas station. I also changed the needle from what was in it to one out of the rebuild kit I ordered. And it’s running better know expect at WOT then it falls on its face, Gonna tackle that next.

No eBay APP ID and/or Cert ID defined in Kunena configuration

zed1015 wrote: If you are running no airbox or pods you really need air corrector jets fitting to cure the off idle flat spot and improve running.

Are these the ones in the float bowls? The ball and pin?