225 compression test

[islandboat]

I check the compression twice a year on my 1999 225 Johnson. Change the plugs, water pump impellar and foot oil once a year. I have run into this same question each time I do a compression test and never ask anyone about it but tonight I read a post that stated to remove all plugs before the compression test. I warm the engine first and use a remote starter button to spin the engine. If I remove all of the plugs before starting the test the starter will not stay engaged for more than a few revolutions. I have to keep 3 plugs in to keep enough load on the starter so it will not spin the engine too fast and dissengage before I get a good reading.I also open the throtle all the way, don't know if that makes much difference but that's the way I was taught in school. I never have a starter problem after "buttoning everything up" and using the boat the rest of the year. Is it normal for a starter to spin an engine with no plugs installed so fast that it disengages the starter drive?

 

[Dhadley]

Re: 225 compression test

Thats the way 90 degree loopers act. I usually loosen all the plugs and then take out one at a time to keep the starter engaged. What you see is perfectly normal.<br /><br />Opening the throttle -- or not -- doesnt matter. Just do it the same so you keep your reference to the baseline. Use the same gauge too.