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riddon(at)sent.com
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 Posted: Sat Sep 01, 2012 1:02 am Post subject: 912S sprag clutch |
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I often have a bit of a problem starting my 912S when it has been stopped for while but is still just warm. I was at the rally yesterday and it took me longer than normal to start the engine after about 4 hours stopped. Lots of kickback etc. I tried on one mag, both mags, with throttle, with choke and no throttle. I have a fairly new red battery and the larger starter motor. I wondered if the sprag clutch is starting to fail? Engine has done 650 hours. From those who have already replaced their sprag clutch, what are the symptoms and at how many hours?
Richard Iddon
G-RIXS
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ward.t(at)xtra.co.nz
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| Posted: Sat Sep 01, 2012 1:30 am Post subject: 912S sprag clutch |
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Richard,
My Rotax Sprag clutch went at 300 hours and starting problems, nasty kick backs are symptoms. Some grinding noise when starting and longer to start, not engaging probably so worn out. Not good to carry on as it could do a lot more damage with parts disintegrating.
Expensive repair. I have the original starter and can't replace it with the heavy duty one but that is not the problem. The battery is more important I believe so I replaced my old battery with a very powerful motor cycle lithium IRON battery, excellent. Also had my gearbox tightened up. Now working fine. It was usually a winter starting problem and cold engine. I still heat it up in winter with a hair dryer, 5 mins can get the oil from -4C to +4C starts much better.
Cheers,
Tim
Tim Ward
12 Waiwetu Street
Fendalton,
Christchurch, 8052
New Zealand.
ward.t(at)xtra.co.nz
Ph 64 3 3515166
Mob 0210640221
On 1/09/2012, at 9:01 PM, Richard Iddon <riddon(at)sent.com> wrote:
| Quote: |
I often have a bit of a problem starting my 912S when it has been stopped for while but is still just warm. I was at the rally yesterday and it took me longer than normal to start the engine after about 4 hours stopped. Lots of kickback etc. I tried on one mag, both mags, with throttle, with choke and no throttle. I have a fairly new red battery and the larger starter motor. I wondered if the sprag clutch is starting to fail? Engine has done 650 hours. From those who have already replaced their sprag clutch, what are the symptoms and at how many hours?
Richard Iddon
G-RIXS
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dg.watts(at)talktalk.net
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| Posted: Sat Sep 01, 2012 1:42 am Post subject: 912S sprag clutch |
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Richard
When I had the 912UL engine in my Europa I managed 900 hours before the
sprag clutch needed replacing. On the 912ULS currently installed it started
showing signs of needing replacement at 600 hours. Also I have heard stories
of 400 hours or less before replacement required.
The signs are apparent when trying to start the engine, especially when
cold. When you turn the engine over to start it suddenly violently kicks and
turns backwards a blade or two.
I have not found this to be a problem when warm.
There is a possibility that your problem was caused by not having the choke
set correctly. An engine that has been run a few hours before is quite
difficult to judge for choke requirement when starting. In fact at the rally
yesterday in similar circumstances I started with just half choke applied.
Also a couple of days ago when the air temp was 30 degrees C I tried to make
the first start of the day with choke and it didn't want to know. When I
removed the choke application it started straight away and ran fine.
Dave Watts
G-BXDY Just off to the LAA Rally again today
--
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kheindl(at)msn.com
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| Posted: Sat Sep 01, 2012 4:07 am Post subject: 912S sprag clutch |
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Hi Richard,
I had all the same problems as yourself and others. As I understand it there were a number of reasons:
Early 912S production engine
High compression
Low torque starter motor
Original flywheel not giving the correct ignition sequence on startup
Friction torque in slipper clutch at the low end of permissable range.
I changed the starter a long time ago and it was a big help, but only a sticking plaster.
Pre-heating the engine worked as well.
But the occasional vicious kickback was wearing out the sprag clutch and things would get worse.
Sometimes it would start but seemed to run on only one cylinder for a couple of seconds.
So, I took it to the Rotax agent and he seemed to know exactly what was going on. The engine was removed completely, sprag clutch replaced, and at the same time the new type flywheel installed. Gearbox was removed and the 3 worn spring discs in the slipper clutch were replaced and the friction torque set to the maximum. With the gearbox off, I also had the oil seal at the rear of the box replaced, and that was no easy job. I always had a tiny oil leak from there since new.
While the engine was out, we also removed the two mounting frames, had them sandblasted, professionally inspected, and then powder coated. I also did a thorough cleaning and polishing job on all components, especially the exhaust. Made some wiring changes etc. etc.
Re-installed everything and tried a start. It started instantly, then I synchronized the carbs. The engine starts nicely every time. Not only that, but it also stops more gently. The Rotax man turned the donkey into a real pussycat.
The bad news is: it cost me $ 2600, incl. 13% tax. That was for 20 hours labour plus parts.
You may want to just change the flywheel, which you may be able to do yourself and without removing the engine completely. The wear on my clutch was tiny, but enough to cause the problems.
Hope you get it sorted.
Cheers,
Karl
| Quote: | From: riddon(at)sent.com
Subject: 912S sprag clutch
Date: Sat, 1 Sep 2012 10:01:46 +0100
To: europa-list(at)matronics.com
--> Europa-List message posted by: Richard Iddon <riddon(at)sent.com>
I often have a bit of a problem starting my 912S when it has been stopped for while but is still just warm. I was at the rally yesterday and it took me longer than normal to start the engine after about 4 hours stopped. Lots of kickback etc. I tried on one mag, both mags, with throttle, with choke and no throttle. I have a fairly new red battery and the larger starter motor. I wondered if the sprag clutch is starting to fail? Engine has done 650 hours. From those who have already replaced their sprag clutch, what are the symptoms and at how many hours?
Richard Iddon
G==============
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[quote][b]
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graeme bird
Joined: 15 Jul 2010
Posts: 434
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| Posted: Mon Sep 03, 2012 11:44 am Post subject: Re: 912S sprag clutch |
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I dont know about the sprag clutch but if my previous 912S had been run the technique was dont touch the choke at all. 3-4 cycles of throttle and then go. On the rare occasion this didnt work then repeat.
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_________________
Graeme Bird
kit4 (Wagstaff) TBD
Kit3 G-CLXU (Gregory) mono 914 xs Woodcomp
Kit2 G-PATS - (kesterton) Mono Classic 912 warpdrive
Kit 1 G-UMPY - Mono Classic/XS 912S, Woodcomp G(@)gdbmk.co.uk |
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phillik747
Joined: 04 Apr 2012
Posts: 73
Location: Birminham, AL USA
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g-iani(at)ntlworld.com
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| Posted: Tue Sep 04, 2012 7:59 am Post subject: 912S sprag clutch |
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Kyle
I cannot give you numbers but the ConAir soft start module is well known in
the UK.
It is LAA approved as a standard modification SM12305 (See the LAA site) or
is available on the Club web site
http://www.theeuropaclub.org/wp-content/uploads/2011/12/SM12305-SoftStart.pd
f.
Ian Rickard G-IANI XS Trigear, 300hours
Europa Club Mods Specialist
e-mail g-iani(at)ntlworld.com
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rlborger(at)mac.com
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| Posted: Tue Sep 04, 2012 8:00 am Post subject: 912S sprag clutch |
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Kyle,
Rotax Owner has a good video on the Soft-Start Module:
http://www.rotax-owner.com/all-videos -- bottom of the page.
It seems to be worthwhile.
Best regards,
Robert Borger
Sent from my iPad
On Sep 4, 2012, at 8:24, phillik747 <helperpsp(at)gmail.com> wrote:
Saw BullyHawk / ConAir Soft Start Module today while surfing the web and didn't know if anyone has used it/heard of it before.
Review:
Purchase:
Kyle
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