Cold Start Fast Idle?

My new-to-me 2004 Swing starts, runs and rides great. However, when starting out, the cold start is excellent and it immediately idles cleanly, but not a fast idle. Is that normal? I am under the impression that there is nothing short of holding the throttle open a little to help it warm up. What is anyone else's experience? Am I worrying about nothing?


Ron in AZ

Don't worry, if it idles cleanly then it's running fine. There is no need to run a modern engine up to temperature before use, just start it up and ride it.

I usually only see a slight increase in idle speed on cold days, on warm summer days I hardly see any increase, but the fact that is holding a steady idle at start (slightly lower than full warm), clearly indicates the idle enrichment is working, KIM that is not a mechanical actuator on throttle plates, but an idle air by-pass/enrichment circuit, actuated by a very old tech/reliable "Wax Unit".

Ok. I guess I will just continue to enjoy riding it.

Thank you for the responses.

The cold start fast idle is controlled by air which bypasses through ports around the butterflies (which are sealed at idle). The wax unit opens a bypass around the butterflies more when cold, and as the coolant temperature rises, the wax unit relinquishes control of the bypass to the idle adjust screw. There is one other bypass circuit operating which is the balancing adjusters. These are used to balance the intake vacuum in both cylinders for smoothest idle.

The idle speed at any temperature is controlled by how much air reaches the cylinders, and that is a combination of both the balancing adjusters and the wax/idle position.

If the cold start idle is too low (not enough air reaching the cylinders) then it is likely that the balancing screws are set too far closed.

Normal operation on a cold start should be for the idle speed to start around 1800-2000 and then progressively drop to the warm speed of 1300 rpm.