compression reading

J

jimmy3262

Member
What would you say would be the minimum compression reading on any small engine for it to run right. I understand that a leak check is tons better. Just need a base number for a compression test so I can run a quick test then if need be run a leak down test
 
I like to see 90 psi plus. I have also seen new briggs push mower engines run fine at 60. To me 70 is borderline, and on most weedeater/chainsaw engines they won't run at all or for very long if the reading is below 90. I have come across a couple chainsaws over the years that wouldn't run below 175. Most ATV's run in the 130-230 range.
 
Well thanks for the info. I like my gauge is bad i have checked 5 different small engines and I cant get the gauge to go over 30. One was my rider that I use every week and it runs good another was my weedeater which runs good but neither would go over 30 psi. my gauge if fairly new kit from Harbor Freight is their a way to test the compression gauge
 
Jimmy, Try holding the carb butterfly open while cranking. You must have a seal at the spark plug hole . Watch the needle to see if it is setting itself at the highest "flutter" point. If two scales read the PSI side.
 
Hi motoman thanks for the infoi have done tons of test on cars and trucks. You do the same way with small engines right. The gauge hold on the first pull. Most of the engines i tested was i would say 10 or 12 years old just guess on that but would they have the compression relief on them. How long have they been using the copression relief on small engiens
 
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