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HelicopterKasama Srimok 90 › Starter Coupling replacement
09-01-2009 03:31 PM  8 years agoPost 1
speedys4

rrApprentice

Beaverton, OR

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So I was in the process to take the engine out to do some maintenance/checking. When I tried to take the starter coupling out, one of the bolt broke-off. So currently I only have one bolt holding the coupling.

It's still working but I'm sure one day it will strip the shaft as well. I basically went all over the internet to buy a replacement but nobody have this item in stock.

Has anyone fitted a different starter coupling from a different heli? The Srimok has a 5mm shaft, I wonder if I can fitted one from another make.

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09-01-2009 04:57 PM  8 years agoPost 2
dankreed

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Corvallis, MT

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dont quote me on this.. but i am sure i saw where someone used a coupler from a raptor 90.. as i remember they had to do a bit of dremeling on the shaft to create a new flat spot..

hope that helps

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09-01-2009 05:16 PM  8 years agoPost 3
REGULATER

rrApprentice

Bakersfeild, CA

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Get a raptor 30 starter coupler it is 3 mill it will drop right on all you have to do is Dremil or file a flat spot on the shaft for the set screw ,and you wont have any more trouble.

Hope this helps

Mark

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09-01-2009 06:31 PM  8 years agoPost 4
gavinator1972

rrNovice

perth

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exactly the same thing happened to me borrowed the coupling from my rjx x50 and it fitted perfectly

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10-01-2009 06:33 AM  8 years agoPost 5
nyc863

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australia

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my starter coupling just stripped, and I was very careful with its install making sure it was exactly square with the cutouts.

What happens each time you start is the threads on the two locking screws chew a bit more of the starter shaft cutout, until there is a groove carved all the way around, and your starter shaft bearing block is full of little metal shavings!

Unreasonable amount of use? no, I am having difficulty with my YS 91 SR engine and was using the starter repeatedly, but no more than the equivalent of 20 flights if the engine always starts easy. Basically it stripped in 20 minutes of random efforts. I was using the align starter with the one-way bearing.

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10-01-2009 06:37 AM  8 years agoPost 6
Anthony.L

rrElite Veteran

Seattle, WA

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I basically went all over the internet to buy a replacement but nobody have this item in stock.
Well I don't know how far you got on the internet...but I just got one today in the mail. I know of two places right now that have it in stock ready to ship, and I only looked at two places. There are 6 more to try.

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10-01-2009 07:23 AM  8 years agoPost 7
nyc863

rrNovice

australia

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the Raptor 30 5mm coupling works I think. (not the v2 coupling which is for 6mm). It has two grub screws.

The Kasama coupling perhaps needs those bolts cranked down REALLY tightly so the coupling grips, and use loctite as well on the coupling, not just the bolts. Otherwise the bolts will chew up the shaft as just happened to me.

I am worried about stripping the heads of the bolts. They are not large enough considering the hammering this part gets. No idea how you'd remove the coupling then..

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10-01-2009 06:39 PM  8 years agoPost 8
bigote

rrNovice

IL,PH

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hirobo starter coupling will do also, i replaced mine with my old hirobo sceadu 50 starter coupling. just make sure you make a guide for the screw to press.

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10-01-2009 06:55 PM  8 years agoPost 9
speedys4

rrApprentice

Beaverton, OR

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Well I don't know how far you got on the internet...but I just got one today in the mail. I know of two places right now that have it in stock ready to ship, and I only looked at two places. There are 6 more to try.
The coupling was really tough to find in the US back in the beginning of the month when I originally post this message. But yes you're right most online vendors have it in stock now.

I'm on my 3rd starter shaft right now because no matter what I did, it kept on eating the shaft. I end up drilling a hole through the starter shaft to fit a 3mm set screw since there's already a hole in the coupling. It's working great now, I'll try to post some pics later.

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10-02-2009 06:42 AM  8 years agoPost 10
nyc863

rrNovice

australia

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I should buy a new shaft but the wait and shipping is too long so I'm going to try to work with my eaten shaft. I've the Raptor coupling here and it is quite usable with two fat grub screws I think I can file flat spots out of the mangled groove..

Really this coupling design sucks I can't believe they didn't notice during testing that it will happen sooner or later to any user and especially fast if they have a tuning or starting issue.

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HelicopterKasama Srimok 90 › Starter Coupling replacement
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