high performance carny running lean

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motorized kodiak

New Member
Aug 3, 2013
105
0
0
australia
hey everyone, my bike is 4 stroking, it is running lean, the spark plug colour is white, if i change my jet to a bigger one, it should make my mixture richer, right? and if i do make my mixture richer, would that make it stop 4 stroking? thanks
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
4 stroking is caused by running too rich.
Is it actually stumbling and 4 stroking or is it just running out of power too low in the RPM's?
Are you sure it is jetted lean?
Yes, a larger fuel jet will allow more fuel enriching the mixture.
 

motorized kodiak

New Member
Aug 3, 2013
105
0
0
australia
pretty sure i am running lean because of my spark plug colour is white,and it is 4 stroking when ever i keep a steady throttle,but it could be stmbling, could you tell me what stumbling mean's?
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
A well tuned 2 stroke will burble and miss when simply cruising along merrily down the road under barely any load.
4 stroking when too rich will occur when under a straining load, even at WOT.

Stumbling is what would happen when the carb is starving for fuel from the fuel tank and the engine coughs, spits and jerks as it fires whenever the carb gives a little precious fuel. Reducing throttle position and slowing the RPM's of the engine can show improvement, but is not the correct remedy.