ys 60 st-h

[Spawndn72]

I got a ys 60 st-h(not the st2) in a trade. The guy I got it from says that it runs, but that it runs rough. As old as the engine is and knowing that it sat unused for a few years I am guessing that the check valve and diaphram probably need replacing.

Before I start ordering parts, is this engine worth rehabilitating or should I just go buy an OS 70?
If it matters, the engine is being used in a X-cell graphite.

Thanks,
Todd

[DavidH]

I used a YS 61 ST for a few years till the ST2 came out. The ST ran great. Basically the difference between the ST and ST2. The ST2 had 3 needles, the ST had 2. The ST2 had needle in the carb barrel that controlled the low end. The ST had a midrange and high end needle.
To answer your question, you should not have to replace the diaphram or check valve. The check valve can be taken apart and cleaned with alcohol. The rough running could be that the bearings need replacing. The ST engines ran really well. About $20-25 for a set of bearings and you should be good to go.

David

[Spawndn72]

Thanks David.

The previous owner tried replacing the bearings and that did not help the situation. I just took the engine out of the heli and looked it over. The very last thing I checked was the check valve and I think that was the culprit. It was stuck closed. Which would explain why the coils in the in the glowplug were distorted and why the engine was running rough.

Thanks again,
Todd

[DavidH]

Yeah if you can not suck air thru the check valve. That is the problem. The motor will idle with the check valve stuck or clogged. But when you try to bring it up in to a hover or forward flight. The motor does not really want to run smooth. Most of the time it will run , just not smooth. Check valves are inexpensive, like $7 for one. Is the check valve with the engine the larger or smaller one.

Larger one http://www.horizonhobby.com/Products/Default.aspx?ProdID=YSE0405

Small one http://www.horizonhobby.com/Products/Default.aspx?ProdID=YSE2510

I know the small one says Heli Only. but the larger one is what came with the ST motor. The small one started coming with the ST2.

David

[Spawndn72]

It is the smaller one.
Does it matter which one I replace it with?

Todd