Compression testing procedure question; what am I doing?

[Underdog]

Not to beat a dead horse but I went out with a new expensive pressure tester that I borrowed from the local auto parts store and gave this compression testing another try.
I did as everyone here suggested and opened the choke and set the throttle to full open. Then I checked the compression again. But I'm confused.
When I tested by pulling the recoil starter just through one cylinder compression I got one reading ( 47 psi  ):


Then when I pulled the recoil starter cord fully (like you would to start the engine) I got another reading (72 psi  ):

Then when I plugged in the electric strarter and really spun the engine over I got a third reading  ( 100 psi  ):

I  repeated each of these tests several times and always got the same results (pretty much). Could I be doing something wrong?  So which one am I supposed to be looking at?

[henriksson]

Hi, according to what I´ve learned about compression testing, your first test is of non interest, one cylinder compression ( one turn on the crank ) is of no use. When you take a compression test on a car or a bike, you have full throttle and press the starter button , or kick the kick starter several times  and let the motor turn so many "cycles" ? til the compression tester reach it´s peak if you understand what I mean.......According to the manual, you should pull the recoil starter "briskly" ? a few times, and then read the meter, so I guess you would try again with the recoil starter. Probably you find something like 85-90 to 100 psi, which what I understand means you got a very good compression in your engine. No need to overhaul that motor :-)
Regards / Thomas H.

[Underdog]

Thanks for the input. I was all set to take this engine apart and replace the rings.  
Now what?  I have no idea why this snowblower will not throw snow. Maybe the valves?
Maybe the belt is not right?   You gotta wonder.

[henriksson]

It´s not the valves, the compression is alright. The belt or somethng else who put the engine power to the auger. I was a little disappointed with my machine the first time I tried it, everybody said it was "so powerful" and I thought " naa, not that good really" then I noticed that one breakbolt at the auger was missing, so only one side of the auger pulled in the snow. Mounting new bolt made the difference, now it´s working like everybody says.
Regards / Thomas H.

[Underdog]

I'll take another look at things. I'm baffled at how poor the snowblowing capability is right now.  I have a honda and an Ariens that will easier throw snow 3 times the distance and handle 2 foot drifts. My dear beloved Yamaha can barely get through six inches of light fluff.  :
http://www.vimeo.com/2604216