Raptor 50 - strange problem.

[jyymbo]

Hey everybody -

I have a Raptor 50 with an OS 50SX-H engine. I flew this for the first time last weekend. It started with absolutely no problem at all. I did a little bit of hovering and adjusting the trims and called it a night (it was getting pretty windy). I went through almost a whole tank of fuel. We had some pretty rainy weather since then, but was able to get it out tonight. Me and my brother took it to the field, filled up the fuel tank and tried to start it up. When I put it away after last week I plugged the muffler with a small piece of paper towel to stop excess fuel from dripping out. I forgot to take that out when I started it tonight. I tried to start it twice before I caught this. I then took the paper towel out and began trying to start it again. It would not start. As I tried to start it - my brother plugged the muffler a little with his finger just to get some fuel into the carb - it started, but at a really high rpm and then stalled out within about 10 seconds. My initial thought was that I flooded it maybe - so I took the glow plug out and cranked it a few times to flush the engine out. Tried to start it again and same thing - started at a really high rpm then stalled out within 10 seconds. After about 10 attempts at starting it - all with the same result - I gave up and called it a day. I noticed a black powdery substance on top of the main fuel tank - I'm guessing this could be the clutch because I was holding the rotors so they wouldn't spin at that high rpm I was seeing at start up.

I didn't change any settings from last weekend when I flew it just fine. Any ideas what could have happened between then and now???? This is my first gas heli and I am really anxious to get it up and running. Please help!



JimO
Erie, PA

[Jimmy.F]

jyymbo,

Just check to see that no other air can enter into the engine without going through the carby (check carby manifold connections, o-rings on the needle, faulty fuel line and crackcase for vacuum leaks (pretty much everywhere except carby throat)).

Anywhere where air can get in will make the engine run leaner, causing it to rev high.

Problems where it's good one day and bad the next, it usually isn't an adjustment problem, but more a failure of a compoments operation (eg loose carby)

Be sure to check the operation of the carby throttle valve to ensure it's working properly (connection to the servo, and that the servo is actually moving it), and check trims to ensure it's closing back to idle position.

Jimmy.F

[RC Man]

Something loose is the most probable cause. Backplate, head, carb, carb parts, pin-hole in fuel line, bad glow plug.

If you use fuel with castor oil it can gum up the motor and cause problems. Make sure you have fresh helicopter fuel with synthetic oil.


:) :cool: