QuestionQUESTION: I have a 2005 CRF 50.I can't get it to idle properly.When I adjust the idle screw to get it to Idle,when you give it throttle,it doesn't idle down quickly.Thats a little dangerous for my 9 year old daughter.I hadn't had this problem before.I cleaned everything inside and out and I can't seem to find the problem.If I pull the idle screw out of the way of the slider,it revs back down normally but then it won't idle.Any ideas?Thanx.
ANSWER: Scott,
check the cable. should have a bit of free play
or slack to allow the carb slide to drop
easily.
Is the slide sticky or moving freely
up and down inside the carb?
A small air leak where the carb connects
to the engine or anywhere on the
intake manifold can cause a lean fuel
condition and keep the engine racing.
Check the gaskets, or any o-rings, rubber parts.
One of the carb screws adjusts the idle mixture
and should be turned in lightly and backed
out a turn or wherever it runs best.
Is the spring okay on the carb slide?
Were the idle and main jets totally clean?
Did you run a small wire through them?
Was float okay?
Check the air filter is not dirty or too oily.
Set valve clearance at .002" when piston
is on compression stroke, valves closed.
"T" mark aligned on flywheel.
Tight valves can cause poor idle.
Is the carb bowl drain hose hanging down
as it should be? It should not be connected
to anything.
---------- FOLLOW-UP ----------
QUESTION: The Cable has play & carb slide moves good.
There aree no air leaks front or back of the carb.
Carb slide spring is good.
Jet is completely clear.
Float is good and working properly.
Drain hose is were it is supposed to be.
Haven't checked the valve clearance yet.
Engine only races for about 2 seconds after the throttle is hit and then it goes down,but only when the idle screw is set to keep the engine at idle.If I back the idle screw out away from the slide,the engine doesn't race when you hit the throttle but the engine won't idle on its own.I tried to adjust the air screw next to the idle screw and it didn't change much.
AnswerScott,
-I would either replace or use some
sealant on the gasket between the engine cylinder
and the intake tube. It sounds very much like
an air leak there.
-Is the fuel petcock valve
allowing a good flow of fuel to the carb?
-did the slide line up okay with the pin
in the carb? The cutaway part on the bottom of slide
should be to the rear or back of the carb.
-check your spark plug, is it black, white or tan colored?
-black is too much fuel, white is not enough, tan is good.
