Compression on old 5HP B&S small engine ....

[Crazy Horse]

This is an older version of the 5hp L-head engines that B&S made millions of, it has the old style ignition with points and a condensor. Any idea what the compression should be? This one has about 80-85 pounds when tested, how does that sound to you?

 

[timcasbolt]

I found a video stating that the compression should be in the 60-90 range. If that's true, you should be good to go.

 

[Crazy Horse]

I found a video stating that the compression should be in the 60-90 range. If that's true, you should be good to go.

Thanks Tim, hard to find that info, B&S just rates the compression ratio. I think some of those had a compression release for starting. This one I have is from an old garden tiller and was transplanted on by someone in the past. It had no spark with the original ignition system, I ordered a replacement coil from Amazon that replaces the original coil as well as the points and condensor at the same time ... so they claim and so do several videos online.

 

[504]

according to the B&S manual you check the compression by spinning the engine backwards by hand and it should rebound clockwise about a half a turn. Of course you need to take the starter housing off. I still have the manual somewhere from high school.

 

[T.R.K.]

As far as I know, those engines have a compression release profile ground in the camshaft, so Briggs never had a published compression spec. for those engines. That said, I have tested some new or nearly new engines, and got around 60 psi on my gauge.

I have also been told that if you can spin them backward -The recoil starter has to come off to do this- they should bounce vigorously back when the piston comes up on compression.