Screeching noise on rappy Titan??

[Made2Fade]

Hi guys... took the raptor 50 Titan out today. Setup the tail and dialed in some pitch curves. Engine seemed fine and had loadsa power. After 2 tanks i start to hear only what i can describe as a screeching sound. It only seemed to be there at higher rpms. Any idea what this could be? Im guessing that the bearings could be gone on the OS 50 hyper. Reason ive put this in the raptor section is because i couldnt exactly locate the source of the screeching so i am assuming its engine related as it was happening at high rpms/headspeed. The engine was purchased with the model from andysadd on here. Piston is reasonably stained (not black or anything) so i take its been used a bit. Any help most appreciated here.
Thanks
Lee

[Made2Fade]

If this is my problem anyone know where i can get bearings for the OS 50 hyper?
Cheers
Lee

[simon_s]

you can get the bearings from www.modelfixings.co.uk.
When you take the engine out check that the pinion gear is tight in the bearing. When I had Raptors I had a few which had come loose due to the pinion wearing hence the reason for the quick uk upgrade

[barney]

When the bearings go in the Hypers it's a slight whine and not a screech. The give away is at idle its gets noisy if they are far gone but its more a knocking sound like a big end in a car.

I suspect the pinion bearing possibly is spinning on the pinion or something in the start shaft area. Another big possible is your start shaft coupling being mounted too high on the start shaft allowing the start shaft move up/down. The coupling should have very little verticle end float.

Another possible is the main gear one way bearing can screech but you usually notice a loss of drive to the rotor head..with that one.

hope that helps you out brian

[Made2Fade]

Thanks guys al check those out more closely but the coupling seems fine, not sure about the bearing itself mind so might check that out before i go stripping engines stc.
Cheers
Lee

[colin n]

i think barney is pretty close

start shaft has caused that on many of my rappys. if u have no vertical play when u pull the coupling up and down its not so good. aim to get just a smidge of play by adjusting the position with the grub screws on the coupling.
a small drop of oil in that shaft and bearing while the coupling is off will help alot.
dosn't sound like the motor.

[3dee]

also you check the clutch lining it might be slipping at higher revs, or the meshing of the main gear and pinion st higher revs it could be missalining

[Made2Fade]

Colin think you could be right buddy, just checked the coupling and it is a tight fit. Ill try putting a drop of oil on the bearing and moving the coupling a small amount off the bearing.
Now that i think about it though the heli seemed noisey when idling. Maybe its both problems? Gearing seems to be aligned nicely 3dee. And i know the clutch and lining are good as i checked that when i had the engine out.
Lee

[HiroboFreak]

Just to give you something else to check....

I once had a similar screeching noise on one of my machines, only at higher RPMs.
I checked various things & all was in order.
It had me scratching my head for some time.

I almost kicked myself when I found it.....

I had put some reflective holographic foil tape on my black CarbonTech blades a few weeks before to aid in the visibilty of the disc (similar to the flash tips on V Blades).

The leading edge of the tape on 1 blade had lifted very slighty causing this noise at high RPM.

Just a thought.

[Made2Fade]

Cant be that as even after i have made sure my blades are tracking properly etc i always remove the tracking tape or any stickers. So i havent anything like that on my blades. Just plain old BBT Maniac 620's. I know that sound though as its kinda the same sound thats made when the covering comes apart from a pair of woodies in mid flight.
Cheers
Lee