Re: 2-stroke vs 4-stroke spark plugs;am I dreaming

[johnyrude200]

I’m actually starting to wonder if the motor is over-revving in the test tank with a test prop. I’m going to set up a tach on the motor and see what type of RPM’s it’s turning. Since it pre-dates CDI powerpacks, it doesn’t have a limiter.

I’m wondering if some of the veteran techs know if test props allow for over-revving a motor, which I would think would cause false positive overheat conditions. The service posters by OMC have minimum recommended RPMs for testing motors out, and I spend the majority of my time testing motors in the test tank with test props. Anything much above 6hp, I generally throw on a test prop.

I’ve found that, even in my 250 gallon tank (which is only a tad below the minimum recommended size…some day I will build a custom test tank that is large enough to run regular props…when I have a big back yard!), I get a lot of false positives where air pockets form behind or around the water intake at medium to high RPMs. I try to turn the motor to either side to get the water swirling around the tank, but particularly with thru-hub exhaust motors, the water just plain turns into a bubble bath.