dc
05-18-2004, 02:39 PM
I got a compression tester a while ago and I just used it for the second time yesterday. I was testing the compression on a two cylinder motorcycle and I came up with some questionable results. The first cylinder read 146 psi. The second cylinder read 115 psi. This tells me that there is something wrong with the second cylinder. So I put a couple squirts of oil in that cyl., screwed the tester back on, and cranked the engine. The compression jumped up to over 250 psi!! This can't possibly be right. The compression ratio is only maybe 9.5 to 1. I decided to check cylinder 1 with a little oil. On this cylinder I got over 270 psi!!
So I have determined that cyl 1 has more compression than cyl. 2. Too much more, in fact. Enough to signify that something is worn out in cyl. 2. Whether it be the rings or the valves I do not know.
Another thing. I thought that an engine would not start very well if it had less than 100 psi compression. Well I have a very old oil burning JD lawn mower that I could only get 75 psi out of but that thing will start right up.
Can anyone give me some advice with my compression tester?
So I have determined that cyl 1 has more compression than cyl. 2. Too much more, in fact. Enough to signify that something is worn out in cyl. 2. Whether it be the rings or the valves I do not know.
Another thing. I thought that an engine would not start very well if it had less than 100 psi compression. Well I have a very old oil burning JD lawn mower that I could only get 75 psi out of but that thing will start right up.
Can anyone give me some advice with my compression tester?