RCU Forums - YS-120 NC help

Hi All,

I am having a problem with a YS-120. I bought 2 of them for a twin scratch built pond racer. They were both taken apart and put back together with "leak free" gaskets. A peculiar difference between the teo motors was that inside one regulator was a small copper disk that looked about like a hearing aid battery. The other motor did not have this copper disk inside the regulator. When I started each motor, the one without the copper disk inside the regulator ran perfect. With a 15X10 prop it tached at approx. 9200 RPM and had a nice idle and transition. The other motor that had the copper disk in the regulator from the start, would only start at over 1/4 throttle and when i tuned the high end would only turn the same prop around 8700 rpm, then when i would bring the throttle stick down to between a 1/4 throttle and a fast idle, it would shut off. I did notice that when it would shut off, i could instantly bring the stick back up and it would catch and continue running. It would do this with and without glow heat. I then took the copper disk out to match the good running motor, and i get the same results, it seemed to turn a few more rpms at the top, but would instantly stop when i brought the stick below 1/4 stick. I tried starting the motor at a fast idle and it would maybe only slightly pop, but never seemed like it would run. Also the motor would drip alot of fuel, whereas the good running motor did not drip hardly any. Any ideas, or if anyone has seen this problem and knows the solution, please let me know. I have run many YS's and love the motors, they do usually run perfect, and if they don't something is wrong somewhere. Thanks in advanced.

Bill Adams