3

As per the title, if I'm starting a motorcycle or lawnmower or something similar with a carburetor and I know the mixture is too rich, does opening the throttle lean the mixture out? I've got a klr650 that I can't adjust the pilot screw on yet and it's starting without any throttle or choke when cold, but refusing to start when warmed up.

3

No (or maybe more accurately – not for long), that is why you have a choke. Opening the throttle does allow more air in, but should also be causing more fuel to come in as well to preserve the mixture. It sounds like you might have a stuck choke or perhaps your idle adjustments are off.

That said, when the engine is stopped, there is no airflow to pull in fuel, so you might get a momentary leaning of the mixture if you open the throttle when starting. Be prepared to close the throttle right away, as it won't be good for the engine to rev up so quickly before there is good oil delivery.

  • Wait, what do you mean 'that's why you have a choke'? I thought a choke made the mixture richer. – Hellreaver Sep 5 '16 at 15:35
  • Yes, what I'm trying to say is the throttle controls the fuel delivery (allows in more air which causes more fuel to be pulled in), the choke lets you control air independently of the fuel, altering the mixture. – dlu Sep 5 '16 at 16:27
  • 1
    right, but not in the opposite direction. Only toward the rich side. – Hellreaver Sep 5 '16 at 16:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.