carb jetting methods explained

Michael Forrest /

There's a common method of jetting and there's an advanced method.

About 2 Stroke Jetting

Jetting Calculator Spreadsheet

Re: carb jetting methods explained

oh boy, here we go again!

Re: carb jetting methods explained

I like data. Recently I used a speedo app that outputs GPS speeds to a spreadsheet. Then I make a specific run around my neighborhood, it's a few long flats from a stop. Usually also tryn time myself from a stop to a specific landmark. make small changes. +/- deg timing or +/- jet size, needle clip etc. plot em all overlapping and you start to see hey I got better pickup but crappier top. i'll try keep the needle and see if I can up the main or whatever.

But to go from experimentally validated trial and error to theoretical models, and just assuming away the lots of finicky little real world variances, I have a hard tie getting on board. sure as a starting point but not without validating w/ some tweaks

I also have a combustion analyzer, you can see when things are way off by the CO or off-stoich O2 but its not super responsive

Re: carb jetting methods explained

Michael Forrest /

I agree with you completely but despite 45 years of experience with 2 strokes I couldn't figure out why the jetting was so weird on my AX100 until I made this theoretical analyzer and it made it obvious that the needle taper was too steep. And given the fact that elevation, temperature, humidity, and % alcohol all affect jetting you'd have to have an IQ of 200 to figure out in your head what changes to make with any combination of changes. I think this is an excellent tool that everyone needs in their computer toolbox.

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