Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I borrowed a  pressure tester from the local auto parts store and tried testing the compression on this Yamaha 8hp snowblower engine.
I opened the choke and set the throttle to full open.  But I'm confused.
When I tested by pulling the recoil starter just through one cylinder of 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?

friiy wrote:

I did take the cover off that conceals the belts yesterday.  I looked around in there. (The cover is still off) I was reading up on the snowblower's manual trying to determine if the tension is adjusted correctly on the belts.  I have had the belts off completely before.  I compared the old belts to a set of new unused ones that previous owner had supplied along with some other parts.    The belts look good and match the original replacement part number.  I am not sure about the tension on the belts.  There is some slack but I have not figured out how to move the clutch wire.   As for rototilling, we have a long long long way to go.  The only hints of spring here are frost heaves and pot holes.  You are spoiled out there.

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