Vintage Dirt Bike Q & A

This is one of the best articles I have seen on the explanation of the differences between the two types of carburetors. It includes a nice conversion chart.

nola_fiddy

In the article included, Amal type is Mikuni and the Reverse type is Keihin.

FYI,
nola_fiddy

I am pretty sure Amal is the hex head mikuni jets and the reverse is the mikuni round main jets. This article never refers to any carb but mikuni, are you sure it relates to the keihin. I ask because I thought the keihin and mikuni jets were not the same.

You may well be right. I have only looked at a limited number of Keihin and Mikuni carbs and only had to re jet 3 of them. How it relates to keihin is with the chart. I had a 155 main jet in my 1979 cr125's keihin carb. The carb leaked and it was too hard to find parts so I converted to a vm round slide mikuni 32mm. I came across this article while googling for information and noticed that the chart pretty much worked as a conversion chart for the jets. I use both a mikuni 300 and 290 main in my bike depending on fuel and time of year (gets hot down in LA). The chart worked right on for two other cab conversions on older bikes.

Hope the information helps.
nola_fiddy