Carby NT Carb Tuning Basics

if you have acorn nuts on those studs, be sure they're not binding at the top - either break the tops off, replace with regular nuts, or add enough washers to give them more room inside
 
I was riding home last night and my bike started actin funny, it would die when I stopped it would start with full choke and run while I fiddled with the choke between open and closed. I made it home, luckily I was only 2 mi.out. today I cleaned up the motor and started process of elimination fuel line, filter, sparkplug dry n tan. I pulled the carb slide out and the mainjet had rattled out so I pulled the carb cleaned the jet put loktite on,figured while it's open I'll check float height it was at 5/8" or16mm i set it 21mm,i took it for a ride it runs good @WOT,but it has flat spot in the middle, needle is set on topnotch. Anyone have a suggestion?
 
Ya I was gonna raise the needle a notch and see that helps or raising the float a hair
 
So do i need a new main jet?

My bike starts to choke out? Bog down? After 75% trottle. Does that mean its to rich or lean? What size main jet would i need? Please help thank you.
 
could be too rich, but 2-strokes will do this of revs aren't high enough to take extra throttle opening - if you are slowly building up speed & this happens, I'd try lowering float level to see what happens & if it helps, I'd try a smaller jet
 
they allow more air to flow when you have made performance mods to the motor
 
Great tuning tips for the NT. This little carburetor is a good design. Simple & way less quarky than the 4 stroke carburetors the HS142 Honda clone engines use which I've had nothing but problems with. The NT carbs almost never seem to fail & are easily modifiable. I replaced a 4 stroke carb with the 2 stroke NT carb on my HS142 4 stroke engine & it starts up every time with no issues. Gas mileage seems to be a bit less with the NT carb on there but I think it was worth it.
 
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