We're told that there should be no drop in RPM during the run-up check when left or right ignition is selected. However, I'm getting a drop of 15-20 RPM (at 2000). Is this a problem?
We're told that there should be no drop in RPM during the run-up check when left or right ignition is selected. However, I'm getting a drop of 15-20 RPM (at 2000). Is this a problem?
The two ignition boxes "talk" to each other and know when the other is off, shift timing slightly to compensate.
You may be able to see 5 or 10 depending on how sensitive your tach is. If you are seeing larger drops 50 plus you may need to service/replace spark plugs or have an issue with the MAP hose for the ignition boxes. Watching what the EGTs do when on Left or Right key positions may help point to a particular cylinder if it is only one.
Pete Dougherty
Customer Support Manager
Cub Crafters Inc