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Old 06-06-2004, 11:13 AM   #1
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Default Vigor and YS 91

OK, a couple of questions for all you experts out there!! I just aquired a very nice Vigor CS. It currently has an OS .61 for power and I would like to replace it with a YS 91 (I have a chance to get one at a great price). As I understand it, the YS will drop right in IF I use the 10t pinion on the 84t main gear. My question is, what else needs to be changed or modified to make this work (other than blades of course). I've been told I'll need a new collet to fit the YS..True or False?? Also, if any other mods are required, where to get the parts?? Thanks for your help!!

Ralph W.
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Old 06-13-2004, 10:53 AM   #2
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No mods required for a the 8.4:1 ratio. If you decide to try 8:1, you'll need to wallow out the frames a bit (the engine mount holes, and the start shaft bearing block frame holes), or mill the mount 1.5mm, so that the engine can slide a bit further forward in the heli (to allow for proper gear mesh).

The lower collet will be a tight fit, but you don't need to get a different one.

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Old 06-26-2005, 10:00 PM   #3
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Take the time to convert to 8:1. It is well worth it. I moved the motor mount and start shaft mount over approx 1mm to realign the pinion gear (11 tooth) to the main gear (88 teeth). At 8:1 @ 1750 you are right at the sweet spot of the engine (14000) compared to 8.4:1 (14700).

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Old 06-26-2005, 10:34 PM   #4
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I milled my own motor mount with a piece of wet or dry sandpaper on a piece of glass and about 15 minutes of elbow grease. the hardest part of it was the refitting of the mount to check the proper fit. I tried to have the first mount milled, and they used a fly cutter to do it in one pass, instead of a smaller bit and just moving the table to make a pass on each surface. needless to say, it kicked the mount out of the vice and got it screwed up. It was faster to use the sandpaper, even if the mill worked right the first time.

I had to use the dremel on the startshaft bearing block mounting holes in the frames. A few of the aluminum spacers from NHP tail blades really do a nice job of covering up the mess that guy (did I say it was me? no, it was that other guy) made of the holes in the frames.
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Old 09-01-2005, 11:44 AM   #5
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Or you can visit with Mark Christy at and take a look at both his engine mount and long bearing block custom made to fit your requirement.

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