Head Speed

[Jamez]

I am having problems with high head speed on a full tank of fuel, when the tank is brimmed up the head speed goes through the roof and I get a alot of vibration, enough to upset my new gyro, after a little while of hovering, it calms down, the vibration goes, and all is fine. Any Ideas of how to stop this? could it be anthing to do with the header tank which I fitted a little while ago :? :? :?

[chappers]

easy way to prove it, disconnect header tank and try it!

[Bender]

thats odd, Is this effect really dependent on fuel level or time running?
only thing that comes to mind is somehow you are very lean and the calming down bit is the engine overheating and loosing power
let us know

[Jamez]

Not to hot

The engine dosn't apear to be hot, and there is plenty of smoke, I did have to richen up the low end a bit. I will check the mixture settings again. I will also try bypassing the header tank to see what happens. Meanwhile if anybody else has any thoughts please feel free to let me know. Thanks for the ideas guys, it gives me somewhere to start.

[greig]

hi james

this sound svery similar to a problem i have, and its driving me crazy.

On mine, i can hover ok, or even sit on the ground - then when i flip the headspeed up to 1500+ it vibrates like a bad thing, this sets the gyro off on a mad tail wag. Changing the mixture does make a difference, leaning off does change behavoir but makes the engine compltely unstable and will overheat. Too rich just makes it pop and bang and does not really change the vibration. Im completely stumped, im beginning to think the engine is knackered.

Cheers

Greig.

[Stuart]

How have you positioned the header, is the outlet level with the carb. I've found in the past if your header is higher than the carb then you can get a richer flow at the beginning of flights and when you go inverted it leans a little.

I now position the header outlet as level as possible with the carb.

[greig]

On mine the header is level, where mine probably varies with jamez is that it doesnt seem to make any sort of difference as to fuel levels (would this change any pressures ?) it still does the same thing..

[Stuart]

What engine and muffler are you using ?

[Jamez]

Header

My header is below the carb as per the instructions, and the engine is an OS32, had about 3/4 of a gallon of fuel through the engine so is not realy properly run in yet so it is still a bit rich. The muffler is the standard hirobo 2 peice but is being changed to a torpedo one peice as soon as it comes through. I have reset the needle valve as per the book and richend it up until it didn't run properly, then turned it back a click at a time until I had good engine rev's / speed but still had high head speed, but it stayed for longer this time. I have subsequently found that the gasket in between the two sections of pipe has fallen to bits no doubt this will not have helped. I was having loads of fun last night :lol: :lol: