Jet Info For Some Stock Carburetors

I was looking through some of my spare parts and I have two stock carburetors. One for a 50cc Vento Triton and the other for a 90cc Vento Triton. I had been told in the past that I had to drill my own jets because no jets were made for these carburetors. It really doesn't matter to me now, but I thought I'd check them out to see if the Dellorto 6mm jets I have may work and maybe save someone else from thinking they need to drill jets. I never messed with the pilot jets, only the mains.

Here are some shots of both carburetors. Left is the 90cc, right is the 50cc.

Here are the jets L to R : 90cc, Dellorto 6mm, 50cc

Top to bottom : Dellorto 6mm, 50cc, 90cc

Dellorto 6mm jet installed in 50cc

Dellorto 6mm jet installed in 90cc

Long story made short : It appears that Dellorto 6mm jets will work as replacements for stock Vento jets, and probably others. The threaded section of the jet measures 5.88mm diameter.

I think there are actually a quite few styles of jets that would fit, because there are probably a lot of 6mm threaded jets made in a simliar style.

M6 x 1.0mm thread Mikuni VM11/22 available from 50 to 180.

M6 x 1.0mm thread Keihin that is available in sizes from 60-200.

The main point here is not only to show a few choices for common carburetor setups, but to encourage people to check their jets. Here are some 5mm options.

M5 x 0.7mm thread Mikuni N100.604 in sizes 50-200.

M5 x 0.7mm thread Mikuni N102.221 in sizes 30-240

M5 x 0.75mm thread Mikuni M10/14 in sizes 40-200

M5 x 0.75mm thread Dellorto 1486 in sizes 25-178

There are more out there, but you get the point. Jets may not be made specifically for your off brand carb, but theres a very good chance that you can get something that will. If there are a few styles that fit that may allow for more fine tuning. For instance a Mikuni may be available in 105 107 and 110 and a Keihin or Dellorto may be available in a 108 or something that the Mikuni is not.

I believe the correct way is to measure as shown in this pic. It's where the slide intersects with the throat of the carburetor. Some carbs are oval shaped and average out. For example, a 20mm carburetor may be an oval 22mm wide and 18mm tall.

There is a problem with that for most of us though... we often don't have mics that can get in there to get a proper measurement. A couple of other ways people try to measure is the carburetors outlet (toward intake manifold) and the silde or slide passage.

Here's a 19mm Arreche measured at the inlet side at 19.05mm.

Before you think that's a great way to know exactly what you have, here's a 26mm Mikuni knockoff measuring 26.94mm at the outlet.

Here's the same 26mm Mikuni knockoff being measured at the opening for the slide at only 22.59mm.

I didn't get a good pic, but the Arreche didn't measure to it's 19mm spec in the slide passage either.

You can look through the carburetor and get an idea of just how accurate a measurement on the outlet side may be.

Here's the Arreche looking from inlet to outlet. You can see that it remains a constant bore all the way out.

Here's the Mikuni knockoff looking from outlet to inlet. It definitely does not remain at a constant bore.

My stock carbs measured 18mm at the outlet. I've been told they are 17mm.

It appears that you can get a reasonable estimate using the outlet's measurement and looking through the carb to see how it's setup.