600N - Change the main gear for a high head speed

[ticedoff8]

I have been flying my Trex 600N Pro DFC with a YS 56SR and I just changed to a new YS 60SR.

The YS manuals say the "Practical RPM" for these motors is 1,800 to 18,000.

Assuming 18,000 is the "red line" and also the peak power RPM, and using the stock gear ratio in a Trex 600N (8.5:1), the maximum head speed is 2100 RPM.

I do not want to hear from anyone that says "Oh, its safe to run these motors at 20,000 - I do it all the time" - thanks, but that is you.

Does anyone know if there is a drop in replacement pinon / main gear set that lowers the gear ratio to around 8.0:1 (2250) or 7.8:1 (2300)?
"Drop in" as in no frame modifications required to maintain a good gear mesh.

I've read there are other pinions available.
I assume I need to slot the motor mount & starter shaft mounting holes to get a good gear mesh with the new pinion.

[Sirolf]

If you are lowering your ratio then you are putting more stress on the engine which will bog easier..
My advice is to try out different headspeeds around 2000-2150 and see how it handles.

To my knowledge there isn't any drop-in fit replacement gears available.. i know cause i needed to drop mine to 7.4:1 to make use of a .91 engine.

[fullerfab]

here you go http://www.infinity-hobby.com/main/i...p?cPath=32_126

[Sirolf]

I've got the 23T pinion of infinity. Although it is a drop in fit, the teeth of the pinion needs to be grind down a bit to get a proper mesh or slot the frames to move engine and clutch-housing forward.

[Bladefx]

if you decrease your collective pitch you gain power maybe try that .
I'm very happy with 10 collective 10 cyclic

[ticedoff8]

The stock gear ratio (170 tooth main gear, 20 tooth pinion) is 8.5:1
The motor "red line" is 18,000.
At 18,000 RPM, the head is turning at 2100.
I would prefer to run the motor a little slower that 18,000 and still keep the head speed around 2100.
With the 170T main & a 21T pinion that is a 8.09:1. At 18,000, the head is turning at 2220.
If I use the 8.09:1 GR, and I fly at 2150 (which is the speed I use on my 600E), then the engine is turning at 17,300.
That's a good RPM in my mind.

The issue now is getting the gear mesh right between the main & pinion.

I supposed I could slot the 4 engine mount & 8 starter shaft housing screw holes in the frame. Maybe all I need it 1mm or so.

[Sirolf]

Are you really going to notice a RPM difference of 700?

Best to run it in the engine's power band.

[ticedoff8]

Interesting point.
What is the power band for a YS 60SR?
I talked to the Service Tech at YS in Reno - he didn't know.
I know the "practical RPM" range to 1,800 to 18,000.
OS publishes both the Practical RPM and the peak power RPM - YS does not.

So, what is the "power band" for a YS 60SR?

[Sirolf]

I bet it's somewhere between 16-17.000.
Do some tests and get a feel for good power.

Getting a different gear ratio will also put more strain on your engine..

[Zbawer]

I've been using the 23T and 24T pinions from infinity hobby in my Big Block conversion, using OS91... it works great!
For you on a YS60, im pretty sure you'll have plenty enough torque to run the 21T, mabe even 22T if you're good with collective management ...

Check out that page on infinity hobby :
http://www.infinity-hobby.com/main/p...366fe386fd6c53

They're giving you the distance between main shaft and pinion / clutch depending on different pinion sizes, with 21T you'll need to grind the 4 screws for the clutch bearing block about 0.5mm forward.
Easy-peasy !

[ticedoff8]

I bought the 21t & 22t pinions, but they don't have the 23t pinion in stock

I am now planning to go Big Block instead.
I changed to the new 3 bladed 550 / 600 head, and the YS 60SR is not up to the task.