Thinking back on the original question about low compression. What is "low compression"? The reason for the question is because most of the manufacturers have not established numerical criteria for compression values in their engines. They have compression, or they don't. They run, or they don't. Another issue that comes up with compression is how it is measured. Two people can have engines identical in every way, use the same compression gauge to determine peak values or leak downs, and have different results. The same compression gauge, set up and installed only slightly different, will provide different results. If you have a hose attached to the end of the gauge you will obtain a lower value than someone that has a straight plug adaptor on the end of the gauge.

How does one check compression by flipping a prop? Do you flip in the running direction or opposite the running direction? The answer here is to flip opposite to the running direction because that is the direction the ring was designed to provide the best seal. Note that rings are beveled on one side for that purpose. Never check compression with a dry engine, and never check by wetrting the inside with straight oil. Both methods provide incorrect values. Check compression using the same fuel mix you will run the engine with.

I agree Pat, but in this situation this engine had VERY weak compression, so weak that it would have wind milled freely if it died in the air. I don't think the original poster was looking for any numbers, just some kind of comparison to see if his engine was healthy and whathe could do about it,believe me, it was not healthy. Do I see some more extensive testing to come up with some baseline compression stats on our little engines, can't think of anyone more qualified to do it, what do you say?

It's a subject that is in current discussion.....

My previous was more to let people know about the lack of standardization and subjectivity throughout the industry.

I flew my cap today and it was not the best day but I was able to get two flights on it. The wind was gusting before storms came through. It was rich, I brought it in and leaned it a little and it was still rich but I will fly it there a while. I can't put my finger on it but even when it was new it was diffrent than the one I got back? I heard one run on you-tube and my rebuilt engine sounds like it, but before it was rebuillt it did not??? I know it sounds crazy.

State of tune effects running tone. If you had an engine that ran poorly and have one that now runs well they would sound completely different. You Tube audio quality is 100% dependant on the quality of the recording equipment, and even with the best will not reproduce as well as the production equipment. Gotta give things a little lattitude.

I see you are at about 2300 ft ASL, you will need to fine tune the carb from my sea level settings. I never leave them rich, and being at sea level I never have to worry about the engine being run lean where ever it goes from here.

I flew it more today the weather was better. I almost have a gallon through it and I leaned it a tad more today. It is running great and just a little on the rich side still.

I now have 3 gallons through it and have leaned it out as mush as needed. I leaned it about 1/4 to 1/2 turn (high speed). The last time I flew it after I had landed the engine dies? Once I touch the ground I go to idle and let it roll out and this it when it dies. I richened the low speed and this seems to help I ran out of time and had to go, so more time is needed. Am I adjusting the low speed correctly? It transissions smoothly from idle to full throttle. Can I remove the cowl, leave the engine running at idle and adjust the low speed this way? I know to be extra carefull making the adjustment and then backing away before going up on the throttle.

If you can post a few photos of your engine setup, we all could view the photos and possible help find more clues to what may be taking place. I like to solder a cut-off head of a Allen head screw. Solder it to the end of your mixture screws and use a long Allen tool. I made a very long tool using 1/8 dia tube with a cut off Allen hex in one end and a Tee handle brazed on the other end. You can then go trough a very small hole in cowl and adjust the mixture with engine running. There are other ways for various engines. Capt,n

I have a small hole in the cowl now and have been making adjustments by shutting down the engine then restarting it and see If I can tell a diffrence. I can remove my cowl pretty easy so I will do that. The idle is not set too low, I think. After landing and roll out it sometimes dies but not always. I also will change the stock plug with a cm6 and see if that makes a diffrence. I will check the manual to see if it tells the idle RPM and set it. If I do all the above It should idle just fine. After about three gallons of pennzoil 32:1 this engine is really running good and strong. It's nice to be able to find the compression stroke when I go to fire it up.