Mikuni carb with no air screw? What?

[dansvan]

Hello all. I picked up a Tri-z and a Tecate awhile ago. Was looking at the carbs on both and noticed that neither have air screws on them. They are Mikunis, 38mm, have a tall, long round slide, and no external idle screw. One has had the inlet and outlet blended with a flapper wheel, other is stock. Anyone heard of these and how do you adjust slow speed mixture? Thanks. and no the screws are not missing, none of the holes are threaded.

[Maico]

'86 and '87 Tecate stock carbs have no idle mixture screws...and they're 34mm Mikuni round slides. VM34SS Mikuni's 2 B exact.

on these carbs....there is no way to adjust the idle mixture....making pilot and needle settings more of a factor.

[dansvan]

VM34ss according to the web is a carb for a yamaha sr500 with an accelerator pump. These two carbs measure quite a bit larger than a 34mm. They also have the long lever style choke instead of the black knob the stockers came with.

[Maico]

There's more than one VM34SS. I saw that too when I was researching Tecate carbs.

[Yamaha_Rules69]

I agree on the tecate carb, there is no pilot screw. On the tri z carb, however, there should be a pilot screw. The carb you have on the Tri Z must not be made for it if there is no pilot screw. I had a tecate carb on my tri z for a little bit, and it didnt run right at all. I rebuilt my old tri z carb, and used the same jetting as I did in the tecate carb, and it ran a lot better. Have you had either of them running?