700 tail issue???????

[moonmanflyer]

Help people i am struggling to find an issue with one of my 700 and it is driving me nuts.
Right my tail is drifting but only on certain manovers, also seems twitchy and not holding the best.
So far i have changed the following.
Diff tail servo, diff gyro, boom, tail hub, Torque tube, had the engine out and taken it apart and checked it all and seems all ok, though it is not running right (is a YS91SR), checked the bearings and all seem ok including the main shaft ones, new head dampers, tried a diff rotor head just to be sure, diff tail blades, diff main blades
Basically it is drifting to the right on backwards manovers and when inverted flying forward same direction.
The only thing that has changed is my outrage muffler has been taken off due to a loose baffle and refitted a hatori, and the engine has been running funny since, reset all the needles and tweeked and fiddled but can't get it right, so, could it be the muffler?? it hunts when in the hover, even with the gov on, oh and a diff gov has been tried
I am baffled what could be the issue.
My other 700 runs the same set up and the engine is sweeter.
Is it a case that maybe the engine is just in need of a major service? Can it be sent to probuild? Is 2 years old ish and never been touched in that time, not even a bearing
HELP

[Nick B]

My m8 had this,James,he did this and that,changed this and that and still had it(tail drifting right).
He had 2 iffy ys engines in the end,popped an os in and its sorted

[sacko]

Put the good engine in the 700.

... Just hope you dont end up with 2 700s that dont run right after!

[mattie-lodge]

James.

Might be worth swapping moduler sections between your 700's with this one. By this I mean the complete tail section..... Complete head section......

For interest what fuel are you running?

[moonmanflyer]

James.

Might be worth swapping moduler sections between your 700's with this one. By this I mean the complete tail section..... Complete head section......

For interest what fuel are you running?

Running opti 30 standard mix, do you think it would be worth running the ys stuff, never have before as i can't get it local

[Jamin_00]

700 tail issue???????

James, probuild have posted on here today saying if your engine needs a service or repair send it in.

I did and have nothing but excellent service from them.

[mattie-lodge]

I don't think you need to change your fuel brand unless you want to, I was just wondering if you had changed it recently.

Maybe try swapping the modules like I said or swap the engine with the other one.

[t-rex pedro]

Headspeed? Tail grips? Boom supports? Also, check the tail control arm as the bearings can corrode and gum up causing problems. The metal upgrade is silky smooth.

[moonmanflyer]

Headspeed? Tail grips? Boom supports? Also, check the tail control arm as the bearings can corrode and gum up causing problems. The metal upgrade is silky smooth.

done done done and forgot to list the last one, also done.....lol
I really do think it is an engine issue now, there is nothing else it could be

[GravityKills]

I've had crazy vibration problems in my 700 with an YS 91 SR and Hatori muffler.
They disappeared - at the price of losing some power - when I shimmed the head with a second gasket. The sound of the engine used to be rather bright, now it is very mellow. It was also idling very badly - they early ignitions sometimes kicked the engine into reverse gear and you could feel it sometimes fighting violently against the starter.

Before shimming, on one day a cold plug solved the problem, but it refused to spool up the next day when the weather was different.

[jay916]

I've also been trying fix a less than satisfactory tail on my 700.

Just a thought, I know you've check most things but have you checked the plastic clutch bearing block. The bearings on the pinion can sometimes spin melting the bearing block moving the cluch bell and pinion out of alignment. I'm suprised they made the part out of plastic in the first place.

Justin

[barney]

James the 700 Tail lacks tail power overall. Even on an optimally set model running 1950 it will turn nose left with a reasonable breeze from the Left especially if you run lots of Pitch.

[moonmanflyer]

Clutch bearing blocks do seem a bit loose and there is float in there, cheers will check that out.
The tail Barney was fine, and on my other 700 is spot on, this is a developed issue

[barney]

Iv'e tested for this on 5 700's using different Tail servo's, Gyro combos both YS/OS engined. All exhibited this without exception.

Bri....

[darryl]

by chance are you running a CSM govenor? I've had the engine hunting before caused by a sensor on my revlock on the way out.. just a thought