TOPIC:

gd4now wrote: Both of the screws shown in the picture appear to be pilot screws - notice the end a screw driver would interface with it is knurled which is what all of the pilot screws I have seen are like and none of the air screws I have see are like.

According to streetfigher, they both were removed from the pilot screw locations, bottom of carb on engine side of the carb as opposed to the air screw location on the air filter side on the carb. I suppose someone in the past could of installed something different than stock, but I just have never seen any pilot screws with the blunt end like these have other than some that the tip has broken off of.

Something that does not appear to have asked, are all 4 of the screws from the original carbs blunt like the one in the picture? Or is it the only one that way?

Sounds right. His description does say "middle of carb, next to the mounting flange". So me and Oldschool were still thinking that, because of the shape of the tip, he was trying to describe the air screw passage at the rear. My bad. Internet communication.......

Good question gd4now, let's see if all of them are the same. That should tell more of the story.

I guess another thing that should be asked is there anything (the pointed tip) still sticking up into the carb throat where the pilot screw enters the carb?

It could be a broken screw tip which is a not uncommon issue with them. If not and the blunt end is the way it was designed then I would think the passageway / pilot adjustment opening into the carb would be larger than those that make use of screws that come to a sharp point.

Nah, I'm pretty sure that pilot screw is broken or cut oft. It will be interesting to see the other three screws.
Good point in looking for the tip. Not hard to do with the carbs on the bench.
I just went through my 26s two days ago and have this fresh on my mind(s).

Good Fortune!

BlackZ1R wrote: The carb mounting flange, to me, would be the portion that mounts into the intake manifold boots on the cylinder head.

Sorry for the confusion. I should have stated "the engine side".



The pilot air screw is blocked off.

gd4now wrote: Something that does not appear to have asked, are all 4 of the screws from the original carbs blunt like the one in the picture? Or is it the only one that way?

Yes, all four removed from the original carbs are blunt tipped.

gd4now wrote: I guess another thing that should be asked is there anything (the pointed tip) still sticking up into the carb throat where the pilot screw enters the carb?

There is no tip left in the passage way. I was able to block the opening at the venturi, the the opening for the fuel needle and seat, and the pilot jet opening and blow through the pilot screw passage. (Thank goodness for long fingers.) I could feel aid coming from the small orifice in the carb throat, on the engine side of the slide.

BTW, all the original carbs had "299A" stamped into the mounting flange. The donor carbs had "102 ??" stamped into the same place.



Later, Doug

It is hard to tell from the photo, but are all 4 the same length? I would like to think that at some point in the past the tips were broken off of those pilot screws and they were reused with out the tips - but I could certainly be wrong.

As to the IDs stamped on the carbs - the 299A is most likely a set of 2990 carbs which if I am not mistaken came on the 77 1000 A1. While the 102 carbs are either a set of 1024 or 1025 from the B2 a B2A.

I have never taken a set of the 2990 carbs apart, so do not know this via first hand knowledge, but I have certainly had many different Mikuni and other carbs apart and have never seen blunt end pilot screws before. But then each time I think I know about something, I learn I do not know enough yet.

I thought the same thing initially go4now, but if you look at the 2nd picture he posted, you can see a difference in the post size before it tapers too much, they are different and not broken.
And BlackZ1, they were in the wrong place, they needed to be in another set of air screw carbs

Oldschool, I will agree that the blunt ones in the pictures do have a different taper than the sharp or pointy ones do. I stated such in one of my posts. I will also agree that air screws do have blunt ends, certainly much more so than the pilot screws I have seen do. But I have never seen air screw with the knurled ends on them like the pilot screws have. To my way of thinking they would not fit into the air screw ports with that end on them. Instead they would stick out - the air screws I have seen have smooth ends on them with the slot cut directly into them. Now have I seen each and every air or pilot screw out there - no I have not. And as I said, each time I think I have something all figured out I find that I do not know as much as I thought I did or need to know.

gd4now wrote: ...air screws do have blunt ends, certainly much more so than the pilot screws I have seen do. But I have never seen air screw with the knurled ends on them like the pilot screws have. To my way of thinking they would not fit into the air screw ports with that end on them. Instead they would stick out - the air screws I have seen have smooth ends on them with the slot cut directly into them.....

Analysis seems consistent with carbs having both pilot air and pilot mixture adjustment screws.









Good Fortune!

Patton, I remember another member on here talking about how his carbs had both, air screws and the mixture screws. Can't remember what carbs he had though.
Are those carbs 24s off of a 650?

So, if the blunt nose screws Streetfighter pictured are air screws, where did they come from? Never saw an air screw with that shape and straight knurls on the end.

Back to Streetfighter's original question. I'd put the long pointed screws back in your carbs and see how it tunes out at idle. In Patton's own words, Good Fortune .

z1r - there were some kz650s that did come with both the air and pilot screws on vm24ss carbs. From what info I can find there were about 5400 bikes (some B1s ,B2s and C1s) that came this way. There were sort of a transition form the pilot only to air screw only carbs. This info is from the Kawasaki microfiche for the B1 - B3 bikes and provides frame # ranges for the bikes that had these types of carbs. Also interestingly enough Kawasaki suggests for the carbs with both type of screws to tighten the pilot screw up as tight as you can get it and to use just the air screw for adjustment. That sort of defeats the purpose of having both don't you think. But I digress.

As to the pics from Patton I know that some are from a how to clean carbs document on the GSResources site and they are pics of vm26ss carbs. It is my understanding that all of the 26s used on the Suzuki bikes had both pilot and air screws.

I still think the blunt screws in the OP post are broken tip ones, unless the carbs on his machine require some special type of pilot screws that none of us appear to be aware of. I agree if the pointed ones will fit correctly into the original carbs that they are the ones to use.

Hi all, this is an old thread but I've been playing with my carbs and I was confused about not seeing a Pilot fuel adjustment, so I came here for information and found this post.

My bike is an 1980 Kawasaki Z1000A4 MKII (non USA , belive to be for Japan-Europe market), the carbs are Mikuni VM28SS non pumpers.

I took them out for a complete cleaning since every once in a while some of my carbs leaked fuel thorugh the overflow hose, first I tried to flush the bowls and open the tap to see if the debris between the seat & needle will clear off. No luck there, so I finally took out the carbs and went for the full repair service, separate them, ultrasonic cleaner, some parts refinished (screws, throttle shaft, choke shaft) and of course new gaskets and o-ring all around.
My carbs use #105 main and #15 idle along with 5CM18 (or 5CN15 can not read well) needle.

Ok, enough introduction, now for the question. Does this carbs only have AIR pilot adjustments and not FUEL pilot adjustments? could this be like this? I know for sure that it has AIR idle adjustment only because this is on the air side of the carb.

I thought that they did also have a FUEL adjustment on the bottom, but nothing there, not even pluged. Kind of lost here. So you can only adjust the idle fuel by changing the R15 idle jet and by playing around with the air side screw?

Here I point out were I was looking for the FUEL idle adjusting screw, nothing there, not even a lead plug and the screw behind it


Here I point out were the AIR idle adjustment is on the other side of the carb (sorry I dont have a picture of the correct side)


So, if there is no fuel adjustment, wich would be a startpoint for AIR setting with R15 idle jet? My carbs were set up from 1 to 4 1/2-1/2-3/4-3/4 from seat out when running.

Well thanks in advance to all of you for your imput!!

Regards, Martin