Rich or lean mixture

Sometimes your bike won't run or start properly. Often the reason is as simple as it being set too rich or too lean. Here we'll tell you how to tell if your bike is running rich or lean. These may sound complicated to first-time users, but it's easy if you follow the instructions. First, let's explain what these exactly mean.

Too rich means that there is too much fuel or too little air in relation to the amount of fuel.

Too lean means that there is too much air or too little fuel.

Why adjustments can go wrong

-Air filter clogged or too open
-Carburetor nozzle size incorrect
-Carburetor idle or mixture screws incorrectly adjusted
-Air leaks in the intake manifold or valves


Rich mixture - Too much fuel/Too little air

How to identify:

-The engine smokes a lot, the smoke can be bluish or black

-The spark plug is black and sooty

-The engine chokes easily

-Power decreases and fuel consumption increases

-The exhaust pipe may be oily.

What to do:

-Adjust the carburetor mixture screw to reduce fuel or increase air

-Check the nozzles, replace with smaller ones if necessary

-Clean or replace the air filter

-Make sure there are no air leaks in the intake manifold

Lean mixture - Too much air/Too little fuel

How to identify:

-The engine runs hot and overheats easily

-Power decreases, running may jerk and knock

-The spark plug is light gray or white

-Difficult starting and unstable idling

-A little smoke comes out of the pipe.

What to do:

-Adjust the carburetor mixture screw to increase fuel or decrease air volume

-Change to larger nozzles if necessary.

-Check that there are no air leaks in the intake manifold.