Buzz 502 #1 Posted September 18, 2008 I've seen several posts lately telling someone to do a compression test. How accurate are they on small engines and doesn't the automatic compression release (ACR) make them useless? How do you tell if your engine has an ACR? Does anyone do a leakdown test? Supposedly they are more accurate. I had this in one of my files, "How to build and use a leakdown tester": http://www.motorcycleproject.com/motorcycl...t/leakdown.html I'm just curious on how you decide what's wrong internally with your engine. Share this post Link to post Share on other sites
big mike 13 #2 Posted September 18, 2008 K series Kohlers have a compression release that is in place until the motor gets to about 600 rpm.It has been said that a K series can be tested by spinning it in the opposite direction.Leak down would be tough to do with out disabling the ACR also. Kohler twins,Briggs & Scrapiron and Techs?.....I cannot give good information. Share this post Link to post Share on other sites
WheelHorse_of_course 99 #3 Posted September 18, 2008 You can also tell a lot about an engine by properly interpreting a vacuum test (most vacuum testers include a chart to help with interpretation. Most vacuum tester also measure pressure so they are really handy diagnosing fuel system problems. Handy tool to have. :banghead: Share this post Link to post Share on other sites
suburbancowboy 0 #4 Posted September 21, 2008 I tested my old K 341 with ACR and a standard compression tester.It just takes a well charged battery and 20 or 30 revolutions.If they didn't build compression when cranking they wouldn't start.Leakdown testing is probably a better way but I never knew how it was done or what tools or tester you use.I had the valves on my Farmall Cub done and the mechanic said it takes a minimum of 68 lbs. to fire a gas engine.Maybe he meant the 4cylinder valve in head Cubs.Dunno' Share this post Link to post Share on other sites
