Coleman at200-b

[spencer64]

New unit has 50 miles on it and it has had this annoying sputter since day one. It will sputter around quarter throttle(8-12mph). Things I have done;
-new replacement carb
-air filter cone style
-ngk spark plug
-112 main jet
-raised the needle
- changed octane in fuel

All these things and nothing has taken it away slightly better but not great.

Runs super strong top end and initial take off but that cruise speed is annoying.

[Matt DeGroat]

Does partially engaging the choke change anything? If so I would lean towards fuel. I have fixed a few baja warriors in the past, most recently one with the sparkplug wire rubbing on the engine shroud. It ran fine but would simply not idle under any condition. Also you could disconnect the kill harness and see if it changes anything.

[Matt DeGroat]

I just noticed that your model is a quad, I was thinking it was a mini bike, sorry.

[JerryHawk250]

It looks like you probably ruled out carb issues. Check the valves for proper clearance. Most of these engines come from the factory with little to no clearance on valve lash.

[cwright53]

Yes on the valve clearance. I bought one for practically nothing because it would run for 10 minutes and quit and would not start until it cooled off. Valve clearance was less than .001. I set intake to .002 and exhaust to .003. Runs good now but when starting it sometime does not make it through top dead center.