Idle speed

F

Formosa kid

New member
So I just put the tiny tach on my lo206 and tried to adjust the idle rpm at 2300rpm. Is it normal that the rpm range from 2280rpm~2340rpm? Or should it just stay right at 2300rpm. Im having a hard time making it stay at 2300rpm. My idle speed screw doesnt really work that well...when I turn it clock wise the idle rpm would go up but when I turn it counter clock wise(almost all the way out) the rpm doesnt seems to drop. The mixture screw is the opposite. When I turned it clock wise the idle rpm would drop and when I turned it counter clock wise the rpm would raise. Any idea?
 
Formosa kid said:
So I just put the tiny tach on my lo206 and tried to adjust the idle rpm at 2300rpm. Is it normal that the rpm range from 2280rpm~2340rpm? Or should it just stay right at 2300rpm. Im having a hard time making it stay at 2300rpm. My idle speed screw doesnt really work that well...when I turn it clock wise the idle rpm would go up but when I turn it counter clock wise(almost all the way out) the rpm doesnt seems to drop. The mixture screw is the opposite. When I turned it clock wise the idle rpm would drop and when I turned it counter clock wise the rpm would raise. Any idea?
Click to expand...

Sounds exactly as it should to me.
What you are calling the mixture screw, (I assume is the idle air bleed screw - to the left of the slide as you look at it and closest to the airfilter) which when turned clockwise, limits the amount of air drawn into the carburetor (thus richening the mixture) and causes the rpm to drop.

The idle adjuster screw is directly under the slide in the middle of the carb. If it doesn't make any difference turning it out beyond a certain point, then it sounds like you've got the carb too lean (air bleed screw out too far,) or the throttle cable is too tight thus holding the slide slightly open regardless of the idle adjuster screw position.




-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
27 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
CarlsonMotorsports said:
Sounds exactly as it should to me.
What you are calling the mixture screw, (I assume is the idle air bleed screw - to the left of the slide as you look at it and closest to the airfilter) which when turned clockwise, limits the amount of air drawn into the carburetor (thus richening the mixture) and causes the rpm to drop.

The idle adjuster screw is directly under the slide in the middle of the carb. If it doesn't make any difference turning it out beyond a certain point, then it sounds like you've got the carb too lean (air bleed screw out too far,) or the throttle cable is too tight thus holding the slide slightly open regardless of the idle adjuster screw position.




-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
27 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
Click to expand...

My air bleed screw is about 1 1/4 turn out and the c clip needle is at the #2 slot.
 
If it idles at all (anywhere between 1800 and 3000), then I don't touch it. As a smart engine builder told me one time, we don't race them at idle. I want my carb set-up so it produces the power in the area I need it.

As long as your engine runs long enough for you to get in the seat after you start it and doesn't die on the track, it will be fine. Keep the idle somewhere below clutch engagement and above dying...
 
I never won a race at idle ----- yet
Since we can't change jets (by rule) The idle mixture screw plays a role in tuning the carb.
However, it's pretty tough to do without having the engine on the dyno.
It always amazes me how many people change the needle clip position and or the idle mixture screw on days that the weather has changed.
They never have a weather station so they just guess.
BAD IDEA
 
Yep, no races are won at an idle. I have seen a couple lost with a lack of an idle though. ;)

Just make sure you set the idle high enough that when the engine gets hot, it doesn't stall on a caution (or off track excursion.)
 
It's been my experience, with two cycles, that once you get the low-speed set right for on the track racing, they won't idle in the pits.

When you hit it, and the clutch is slipping, is there a point where the rpm drops and the clutch locks up? The reason for that drop in RPM is that the low-speed is too lean. You don't have to believe me, if you're having this problem, richen up the low-speed and see if it goes away.
 
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