4-stroking...

[ParadoX]

Hello, Ive searched the forums and have read the carb adjustment threads, but am still having an issue.

With my e-clip at the 2nd postion, the bike run bad. 3rd position, It rides pretty good, but I have some 4-stroking at higher speeds. Without any other positions to try, how can I fine tune the carb to get a little more air in?

Ive got a boost bottle and sbp pipe if that matters. Carb is the newer grubbee 'speed' carb.

Any tips?

 

[AussieSteve]

It sounds like you might need to go down to a smaller main jet.
With my stock NT carb, I had to go down from 0.79mm to 0.72mm to get my mixture lean enough and still have the slide needle on it's lowest setting.
Does the 'Speed' carb only have 3 notches on the slide needle? (The original NT carbs had either 4, (earlier model), or 5 notches, (later model).)

 

[Biker]

Steve
do the main jets have numbering on them,mines an NT,Needle is set the same as yours,so i need to go down on main jet to.Mines a 48cc
colin

 

[AussieSteve]

Steve
do the main jets have numbering on them,mines an NT,Needle is set the same as yours,so i need to go down on main jet to.Mines a 48cc
colin

G'day, Colin.
Unfortunately, the stock NT jets don't have the size printed on them and neither did the one I got from Rock Solid Engines.
The ones that I got from OzMiniMoto were numbered, though.

You can probably assume that you have an 0.79mm jet.
Mine's a 66cc, and I found that an 0.72mm was best.
Maybe you could start there.

 

[Biker]

Thanks Steve for the quick reply,i may take the jet down to the local mower place then and get him measured first off
regards
colin.