I thought I’d ask the experts here before I drown myself in YouTube instructional videos. I’m looking at possibly buying a 1998 Yamaha 2-stroke with low hours (supposedly). I personally, have never performed a compression test, but would like to buy the tool and learn how to.
Any recommendations on a good quality device for testing? Any pointers on how perform an accurate test?
Thanks in advance for any help
Could be wrong, but I think the technician who serviced my friend’s Waterman that we sold used an OTC Compression Tester. I see there is one on Amazon on sale during Prime days for $80. Seemed fairly easy to do: run the engine for a while, turn it off, remove the spark plug wire (mark/number the wires), loosen the plugs a turn or so and blow out any dirt/debris, take the plugs out (lay them out in order so you know where they belong), etc. From what I understand, you want the compression in each cylinder to be within 10% of one another.
Thanks Dave!
It’s Pretty straight forward. I personally wouldn’t invest in a good brand if your only going to use it occasionally. Dave pretty much covered the jist of how to do it though. I typically do em cold but, warm is the proper way. One other thing to mention, is to hold the throttle wide open. You want the engine to be able to draw in as much air as possible.
Thanks Mike! Good to know. I ordered the one Dave mentioned, on sale. Has good reviews!
AutoZone lets you use a compression tester for free.
Also wheel pullers, and a few other special tools.