When i bring my V1 rappy 30 up to hovering speed i get this noise like crunching or rattling like something is wrong.lol but only at a certain rpm which i dont know which rpm its at anyways at anytime. Also my muffler keeps coming loose even after i red loctited the ******* with a nyloc nut on it? I have a helimax tuned pipe with header for .30 sized engines should i put that on? I have a O.S. 32 SXH motor and i usually run powermaster 15% in it. But recently switched to coolpower 30% and it doesn't seem like it really likes that. Or i just dont how to exactly tune in my motor after repeated readings of directions and other info sites like raptortechnique.com Any advice or tricks, tips, etc. would be oh so deeply appreciated

pe@ce [&o]

Could be a bearing going bad, and/or the tail drive belt is not tight.

going from 15% to 30% will require a richer mixture...15% is fine for basic stuff (and cheaper)

nyloc may not work due to heat...use standard nut with lock washer

Could be engine surge? Do you see the exhaust change in pulses when this happens?

I had this happen on my TT39, i didn't believe it, when sombody told me this was the problem i was having ( i was certain it was a bearing problem) but sure enough, it went a way when i modified my idle needle. (i ground the tip of the needle down to more of a point)

Actually the puffs of smoke are different always different through whole range of throttle !

Sounds to me like your belt is slipping or chirping. Also, make sure your tail rotor blade mounts are secure to the shaft. they could be slipping, but the chances of that are not as good as a loose belt.

It's a cog type belt, with a half twist in the boom, is it's too lose the cogs on the belt will hit each other inside the boom. it would have to be very loose to jump the cogs (slip).

The red loc-tite will not withstand that kind of head, you need to use hi-temp sylicone on the muffler and exaust port. As for the crunching...yes, it is the belt, in cold weather mine does it when spooling up, but when its warm I don't have the problem.

Colin

You need temp resistant loctite (e.g. the green loctite)
Also nyloc nuts will not hold either because of the heat.
Use a lock ring and metal nut.
Make sure you DEGREASE otherwise nothing will keep your pipe in place.

Of course you hear rattling if your pipe is loose Do you have the noice only when at that RPM or do you hear strange sounds earlier (e.g. idling)? Do you have a tuned pipe?