I just went from a 30mm carb to a 34mmTMX carb on my trailbazer. And it's also gotten cooler, about 50 to 60 degrees. What kind of jetting changes should i make going from a 30 to 34 carb (up or down)? And when the temp. gets cooler do you generally go down in jetting? All and all how much of a jetting change should i make (up/down), say if i was running a 180 main.

 

You would go up to a bigger main jet for every 15-20 degrees on a 2 stroke.
Cooler, more air requires more fuel.


Jim
from... 101 ATV Tips- #26


26. A general rule of thumb on correctly jetting the carburetor on a high-performance quad for the weather is that every 15 degrees of air temperature change, up or down, requires a main jet change. You can usually get by on one 15 degree change without rejetting but rarely two. This usually does not apply to 4x4 and utility riders of most four-stroke ATVs which can withstand varying temperatures all day long with no major changes.

 

What kind of difference in jetting should there be from a 30mm to a 34mm carb-(180 to 210)? What is the main jetting in a 400 scrambler?

 

My stock main jet was a 230 i am now running the 260 and moved the clip position down one with my mods.

Jim

 

So I'm guessing i should be anywhere from a 210 to a 220 especially with cooler weather.

 

Not sure about that carb. but bigger main for colder weather.

Bigger than the original jet, make sure to do plug checks.

 

Thanks for the help. I found a 210 main to be perfect.