OK, how about a leak down test on a two stroke?įrom what I've read on internet (good or bad) you place the piston so the rings are above all ports, lock down the crankshaft/flywheel, attach your leak down tester, pump in about 70 psi, and observe the leak rate. the other tech pulled the lanyard not knowing the customer had bypassed the lanyard.ĪLWAYS insure the ign is either disabled OR you can control where the spark is going to occur. The other was a 225 EFI merc that was at the shop. I went and grabbed the forklift driver and said Todd watch this.

One I warned the guys and they told me we know what we are doing. I have seen two merc EFI motors fireball. Pulled the plugs and went to crank the motor over and KABOOM. Mokanic was working on a gas hydrolock issue.

Mokanic got blowed out of the hull,owner got blowed out and landed in his backyard. Had a boat fire here in the harbor about 6 yrs ago. The reason I always use my stevens s48 spark tester when checking compression?ĪNYTIME you deal with gasoline vapors,especially with EFI or DFI motors, CONTROL the spark. Yet the compression was good and the leakage rate above 70%.

I cannot tell you how many 4 strokes have passed a compression test with leaking heads,leaking valves and stuck rings due to carbon. On a 4 stroke it is a teat on a boar hog. On two stroke a compression test is quick easy and painless.

Outboard motor compression tester