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dhardin

What compression should i get?

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dhardin
I checked cold and got 80LBS and after running and checked I got 60LBS.. Whats normal for a 12hp BS in my Lanlord? I am quite shure I need a set of rings. Today was the first time I got to go for a ride on my Lanlord. Thanks to member smilinsam for the fine looking bevel gears I got last week. (Thanks a lot Sam) new gears, reulator and carb kit, was lots of fun to drive around all my hard work today. She puffs a little smoke, and the plug looks very black after just a 30 min. ride, with no real load. Starts in one short crank, runs fine. Iv had the head off and the cylinder looks remarkably clean with very little rig wear. But the rings must need to be replaced. I wish I had a "leak down test tool". The compression seems low to me anyone have other experence and information on compression.

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Salthart
spin the engine by hand backwards to the compression stroke and it should "bounce" off of the compression stroke. ( So says briggs ) You can't check a Briggs with a gauge because of the built in compression release. Its made in the cam shaft. From the way it starts etc, I don't think you have compression trouble.

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DaleC
Salt is right about difficulity checking the briggs because of the release, however, if you have 80 cold, I would say that your compression rings are fine. Oil rings may be a different story. One way to check for worn out rings is to check the engine compression cold and dry and then put in a squirt or two of oil from an oil can and check again. If the compression pressure goes up significantly, you have worn compression rings.

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dhardin
The compression tester i have is a old Snap-On tester that reads the highest compression in a strok. So it must have built up 80LBS befor the cam detent releaved the pressure. I was guessing more like 120Lbs cold and 80Lbs to 100LBS hot. Salt it dose bounce back when i spin it as u said, It runns to go to have all the rings shot. But i am leaning to as well as Dale said I may have a bad oil ring. Rings i dont have a problem with but valves and valve guides i have not done much of. That type of work i would have to take it to a shop. My hopes and consern is to have to only take it down one time for this type of internal work. Thansk guys...

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