Normal for change in idle between hot and cold?

02yz426f

Member
Nov 15, 2006
319
0
When my bike is cold with NO choke, it idles very slowly and almost wants to turn off. When I ride it around and warm the engine, I stop and the engine is idling fairly high. Is this normal? Bike runs great though.
 

Rich Rohrich

Moderator / BioHazard
LIFETIME SPONSOR
Jul 27, 1999
22,839
16,904
Chicago
Fuel can't vaporize properly when the engine is cold so some of the fuel puddles in the intake tract and it runs lean. Once it warms more of the fuel is vaporized and is available in a usable form which effectively richens the mixture.

The choke adds more fuel when it's cold to account for this. Once you turn off the choke the engine stays too lean till all the parts heat up.
 

02yz426f

Member
Nov 15, 2006
319
0
It's normal for my 426 to have the header glow bright red when I just sit and idle for a minute or two. As soon as you get going, the pipe will cool off and turn back to the normal color. I have heard if you ride for awhile and it stays that cherry red, you might have a lean condition in your bike. The 426 I ride, will puke coolant if I idle for about 4 minutes, they overheat very fast. My rule of thumb is that if I am stopped for a minute or more I just shut it off, and turn it on and take off when need be. Thanks Rich Rohrich. Impressive explanation.
 

Ol'89r

LIFETIME SPONSOR
Jan 27, 2000
6,961
45
SFO said:
what if my headpipe glows?


Hey Bill.

You forgot to use this guy---------------> ;)

:laugh: :rotfl:
 

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