I just went down and checked two of my 80's. One I bought brand new when they first came out when I worked for Hobby Shack. The other I bought about 10 years ago. I filled the cylinder at BDC with oil and then again at TDC. They both held about 16.2 CC's at BDC and about 2 CC's at TDC. That gives a comp ratio of about 8.1 to 1, give or take a bit. Guess I got an early oddball. Always wrong, I guess. Another funny little item. The newer one is ABC, too. It has an 8.1 to 1 Comp ratio AS MEASURED. Either that or Saito is wrong too. Weird,huh? You can say what you want but I know what I just measured.

The ABC's run just fine on YS20-20 but I use 10% because I'm cheap and got a great price for it. 8.1 to 1 isn't all that high a compression ratio. Both are ABC's and both have that same volumes and same compression ratios.