noginblue

Just had a weird crash and need some opinions on the matter. Have been trying to work out a problem, the heli will hover ad climb fantastic but when doing a climb and then throttling down to about half way the engine will raise in revs and then go back to normal for a second or two till I throttle up some to level out, just did the same but this time the engine reved up but no matter how much I throttled up the blades lost momentum and didn't have time to auto so slammed into the ground?

BarracudaHockey

My Feedback: (11)

Drop the engine, sounds like you sheard the clutch bolts.

Hold the head and spin the gear, one way it will move, one way it wont. I doubt its the auto hub though.

noginblue

Have checked the clutch and is fine, new clutch with new bolts. Checked auto hub the way you described and works. As I say I have been chasing a problem fir some time with the engine, after full throttle going down to half the heli will hunt badly but it's the engine that is making it hunt, you can hear the engine rev up and down about a good five or so times before it becomes constant again, this happens if it's in gov mode or non give mode. Have changed all fuel line and also tank and fittings.
Can a 2 stroke run backwards and also why would this happen? Had engine tunes pretty well at the time of failure

Have decided to run the engine up on a test stand to see if I can simulate the problem I'm having, what prop would you recommend to try to simulate the rotor loading or would this not make a difference, have a 10 by 10 also 11 by 5 and 12 by 6 and a 13 by 8 to hand

BarracudaHockey

My Feedback: (11)

If the low end is rich, yes they can run backwards and yes, I've seen it happen in flight.

Do the pinch test. Warm up the heli, land, pinch the fuel line closed and start counting. If you get to 5 before it speeds up lean the low end screw.

Check your head bolts, make sure the carb is fully seated, your muffler is tight, and if you have an inline fuel filter, take it out and test with a straight shot fuel line.

noginblue

Will do, also remembered I have a set of head loaders so will use them First to do a static test

BarracudaHockey

My Feedback: (11)

Yikes. Throw those in the trash!

noginblue

Did some testing and it was the main gear one way bearing, checked mixtures and made no difference, it happened when you spool up and throttle down and as soon as you throttle up again one a little bit to load the bearing you could hear it slip, so took it out and cleaned it and put a little light oil in and now works a treat