Hi,
About three weeks ago i was having trouble with my 99 scrambler 400 4x4 when it got to high revs it would miss out our like say the exhaust would not shoot out for a millaseconds like it missed the revs.

So i took it home and let it thaw out. Was riding in foot of snow. Then today i took it apart and moved the air screw about 3/4 a turn clockwise, so now it is doing it but not as bad. So what do i do? anything to do to the carberator?
I am not that bright but if you ask me it kinda sounds like it is getting to much gas, (maybe to little). So I would like some help!

Thanks in advance,

David

 

sounds lean to me. Does it do it only at full throttle? If so check your jetting. Im pretty sure the air screw only does the idle circuit but could be wrong. If it started in colder weather maybe the dense air is leaning it out. Check your plug color and take it from there.

 

Sounds jetted lean. By turning the air screw in, you richened the mix a hair (tightening it down lets in less air). This is only really effective from idle to part throttle. To cure the problem, you need a bigger main jet (and possibly raise the needle, too). Beware, 2 cycle engines do not like to run lean! All sorts of meltdowns or siezures can occur on a severely lean 2 cycle. Far better to err slightly to the ritch side.

 

Ok, How do i rejet it? Or move the needle? I am new at working on these machines.

Thanks,

David

 

Oh, The plug is new, I will check color today. What color should it be?

 

The jet is located on the bottom of the carb. It's held in by the brass colored screw you will see. You need to remove your seat and airbox, and the clamp holding the carb to the motor. If you unscrew the throttle cable housing to the carb, you will see the needle. It is held in place by a small e-clip.

 

Further needle instructions:

Unscrew the top of the Carb.
Pull the the slide out.
Pull the spring back and hold it w/ one hand while pushing up on the needle.
The cable lock should pop up and the needle w/ it.
The "e-clip" is the little bitty clip on the needle.
Pop it off and snap it back into the groove that best suits your set-up????

EC

 

Ok, Which way do i need to move it to make the mix richer?

David