John, your not mentioning what type of fuse your dealing with. I'm assuming this is a profile? Most profiles are susceptible to the shakes this one being the same. It might be a worn out crank bushing. However, some of my best runners literally had the crank wobbling in the case and they ran flawlessly although fuel was coming out of the front of the bushing. I've had issues with this engine as well due to using too much oil. While many on here suggest using up to 29% oil content in the iron piston engines, I found for me 23% was my choice. Even when I used Sig 25% the engine would just run rough and quit typically at the worst time. It certainly sounds as if once the rpm's drop the harmonics begin. What happens when your try and run the engine in the higher rpm's? Does all smooth out? For instance, if your running a 10x6, would a 10x5 fix this? Is the fuel fresh? I would also look at trying another plug that's hotter or better quality than the current one in the engine. The MAX-S is typically a sewing machine, I've had some shakers but this was due to lite ply doublers on the plane or crash damaged planes. With the plug out, you should be able to verify if the crank is bent just by rotating it. Is the drive washer fully seated with no dings or flaws preventing it to seat square on the shaft? If the crank is that bad, it will visually show up. Lose your spinner and put the prop back on and run the engine. Even a prop regardless of balance may not have it's back mating surface parallel to the front bolting surface which will reveal the same appearance of a bent crank. Ken
Topic: OS MAXS-35 (Read 1050 times)