XCell SE 60, convert to 90. What ratio?

[kjkelly]

Considering converting my much loved XCell SE from .60 to .90 power. What I'm unsure of is what ratio to use and ideal main blade lenth. I have an OS61SXH WC in there now with a 90 tooth main and 10 tooth pinion. It has 690mm mains and the 31.5" boom with 105mm tails.

I will put in a YS91ST4. My ratio now is obviously 9.0:1. I've seen some excellent advice on this topic from DavidH in the past, but for the Fury. It does not appear that with a 31.5" boom I will have any trouble running 700's even with 105mm tails. Is my thinking correct there?

Appreciate the feedback, thank you

[DavidH]

Kevin,
I ran 700 mm mains and 105 mm tail blades with a 31.5 inch boom on a P2K. It will be the same on an SE.

For the YS 91 you will need a gear ratio of 8.45 or 8.36 or 8.18 to 1.
If your going to be doing a lot of 3D type flying I suggest 8.45 or 8.36.

If the SE has the screw in type pinion on the clutch bell and is not held in by set screws.
Then you will need 0864-12 11 tooth pinion.

Your going to need 0549-3 motor mount. This mount will be need to move the engine away from the main gear towards the front of the heli. It moves the motor approx 3mm forward.

If you want to use 8.18 to 1 ratio. You can use the 90 tooth main gear you have now.

For 8.45 you will need a 93 tooth main gear 0865-93
For 8.36 you will need a 92 tooth main gear 0865-92

You will need some shims to get the motor lined up correctly.
0549-3 .017 thick shims
115-47 .030 thick shims

For the shims I would get at least a pack of each.

8.36 would be a nice middle of the road ratio for the YS 91.

David