700 problems

[t-rex pedro]

Gotta be that diesel you are putting through it. Change to Rapicon will clear out all the sludge that's probably been left in there

I wonder if it could be your fuel regulator or the pressure nipple thats playing up.

LOL!!!! The fuel is fine. My 600 is sweet on it!

Could be the pressure nipple. I'll check it. I had the fuel reg apart to change the rear bearing and it looked fine.

The heli is great when I'm giving it 'full banana' (ChrisB phrase!) but its really annoying having the tail wander in the hover.

[GravityKills]

I've had also problems with throttle servos.
Once the carburetor barrel got stuck irregularly on a .50. One throttle servo lost its force for unknown reasons (overheated?).

[moonmanflyer]

Check your clunk line, might be starting to go, filter pete, try a new one to be sure.
Maybe the carb needs a clean out mate

[t-rex pedro]

Check your clunk line, might be starting to go, filter pete, try a new one to be sure.
Maybe the carb needs a clean out mate

I'll check the filter and tubing James - good idea. Carb should be ok mate as I cleaned it out when changing the rear bearing.

[mattie-lodge]

Hi Pete,

Don't know if this is relevant but I had a long standing problem with my 700 which I was convinced it was the motor. Eventually I'm positive I tracked it down to the tail area and the action that eventually cured it was taking apart the tail end assembly, cleaning up and re greasing the thrust washers in the tail blades grips and replacing the tail output shaft bearings. I've flown it 4 or 5 time since and it has been fine, but I'm going for a blast tomorrow afternoon so i might take and see if it still ok.

Will let you know how I get on.

or of course follow Richies advice and use Rapicon

[Steve]

The YS91SR can be smoothed out considerably by shimming the head. Buy an extra head gasket for a couple of quid and stick it in. It will smooth out the motor no end with hardly any loss in power. Doing this cured a lot of heli issues with my SR.

[t-rex pedro]

Thanks Mattie. Didnt think of that. Great advice.

[Tim Procter]

Mattie Lodge has 99% covered this but have you checked the tail ball joints are not tight and sticking somwhere Pete.

Won't cure the engine but could be the cause of the tail oscilatting side to side.

[t-rex pedro]

The YS91SR can be smoothed out considerably by shimming the head. Buy an extra head gasket for a couple of quid and stick it in. It will smooth out the motor no end with hardly any loss in power. Doing this cured a lot of heli issues with my SR.

Thanks for that. Interesting. Is this common practice on the YS91SR?

[t-rex pedro]

Mattie Lodge has 99% covered this but have you checked the tail ball joints are not tight and sticking somwhere Pete.

Won't cure the engine but could be the cause of the tail oscilatting side to side.

All ball links are fine Tim. Nice and loose. This problem has only recently developed. I actually thought a knackered rear bearing was causing it but since replacing it the problem is still there.

[Steve]

Thanks for that. Interesting. Is this common practice on the YS91SR?

I can't remember who (someone from the forum) suggested it to me, but I did it and it worked a treat.

[Tom Burgess]

The YS91SR can be smoothed out considerably by shimming the head. Buy an extra head gasket for a couple of quid and stick it in. It will smooth out the motor no end with hardly any loss in power. Doing this cured a lot of heli issues with my SR.

I'm so going to try this, my YS SR runs rougher than a bears arse. I mean terrible, it has been back to probuild and given the all clear but it's still terrible

[Steve]

Fast Lad Performance
Probuild Aircraft Store: Ys 91 SR Head Gasket

Both pretty cheap and ProBuild are more likely to have it in stock. Gotta be worth a try surely?

[t-rex pedro]

Ok guys, tried everything you suggested (except the head shim) and got the chance for a brief hover this morning. No change unfortunately.

However, I did notice that the main gear is not exactly round and has a high and low spot to it. I can physically feel the mesh tighten when turning the rotor by hand against the clutch. The gear is the -1 upgrade.

Do you think this could be the issue? I wouldnt have though a high spot on a main gear would give a 90 any problems but really cant think of anything else that it could be!

[Steve]

I can't remember who (someone from the forum) suggested it to me, but I did it and it worked a treat.

Just remembered who it was........




It was colin_n