That was my biggest dislike of the Magnum (Sanye) .30 four-stroke engines. The high idle.

My OS FS-20 would happily idle at between 2k and 2.2k all day long, with instant recovery. Sanye should really work on this problem. A near 3K idle is unacceptable.

Burning Cool Power fuel in a Sanye engine, two or four-stroke, is a problem waiting to happen. At least switch to Omega so that the engines get some castor oil. Or add three to four ounces of castor oil to your Cool Power fuel. You will even seen an improvement in overall handling if you do.

Surging can be caused by several factors, but I would ensure that your radio setup isn't causing the problems first. An unstable encoder/decoder can easily cause servos to move a bit without command.

If the servos are rock solid, then I would look at such things as the lubrication package of the fuel (you MUST have some castor in the fuel if using American synthetic oils), weak valve springs, crimped or otherwise restrictive fuel tank vent lines or even too small of a load on the engines. The weak valve springs of Sanye engines in conjunction with a prop that lets the engine rev too high could be causing the surging. Rare? Yes, but possible.

This situation is one where I have BTDT and not speculation.

Let us know how you resolve the problem.


Ed Cregger