QuestionI am having all kinds of trouble with my dirt bike. I have spark and gas to the carburetor but don't know how to adjust the idle and other fuel jet to the lower left of the idle screw. I completely disassemble the carburetor. and cleaned it. I had the bike running yesterday but it will just kick over now. It will pop if I pop start it. but then a few seconds later it will bog down. I was wondering if you could point me in the right direction with the adjustments? thanks.
AnswerBrian, start with the basics first....
Compression.... what readings do you have now? Should be 170psi. If not, adjust the valves to .002" at T mark on the flywheel... compression stroke when both valves are closed. If valve adjustment is okay and compression is low, then either it is worn out with worn rings/leaking valves or the cam timing is incorrectly positioned. Compression readings below 140 need to be repaired before trying to force it to run in worn/damaged condition.
Once that part is done, check the ignition points. Should be around .014", just opening at the F mark alignment on the flywheel.
Carb float level is 21.mm, with #35 idle jet and #95 main jet. There are two screws on the carb body. One raises the slide to change the idle speed. The other one is the idle mixture screw which should be 1 3/4 turns out from gently seated in. Idle speed screw is in the middle of the carb body centered on the slide. Idle mix screw is forward towards the intake manifold.
Make sure you have a good clean spark plug, plug cap if resistor type should be 5k ohms. Intermittent spark, even with a fresh spark plug usually indicates a bad condenser, which requires buying the flywheel removal tool and unsoldering the condenser lead in some cases.
Bill Silver
