Engine Idle Speed

On stock 920s (and those bored to 1000 pistons) I like to set the engine idle speed around 800RPM. This also holds for engines with stock (or near stock) cams running higher-than-stock compression. If this is the case, it may be necessary to spin the engine as high as 1500RPM to get it lit, and it should probably stay over 1200RPM until it is properly warmed up.

Now a bike with: 1) larger carb venturis, or 2) long cam duration will likely need a faster idle. If it is fully modified, it will likely not idle well below 1200RPM. If it is also running pipes with a very large (1.75" or larger) inside diameter and/or a very non-restrictive muffler, an even idle may not be achievable below 1500RPM. Keep in mind that back in the day, there were muscle car enthusiasts who found that an idle speed as high as 2500RPM was acceptable -- this with 100+ octane TEL fuel and a redline at (or below) 6500RPM.

More to come . . .

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