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Re: Europa-List: Rotax 912ULS starter motor

Subject: Re: Europa-List: Rotax 912ULS starter motor
From: Martin Tuck <MJKTuck@cs.com>
Date: Sat, 6 Feb 2021 15:06:31
Hi all,

Closer scrutiny of the SkyTec starter shows eligibility for the Rotax 
912ULS Serials 4425001 and on.

I have an older 912UL. Do you know if there a similar hi-torque starter 
available for it?

Anyone have experience installing the SkyTec starter on the 912UL?

Regards,
Martin Tuck

On 12/3/2020 6:47 AM, Bud Yerly wrote:
>
> Martin,
>
> Remember all the posts, SBs, SLs, Sis on Genuine Rotax Parts kept 
> coming on and on?
>
> I normally use Rotax parts on my engine because I can afford it and I 
> plan on selling my aircraft when I get old. My plane and I are aging 
> similarly by the way. But my plane is easier to touch up and is not 
> growing hair out of its ears.
>
> The Sky-tec has the same nose seal as the Rotax. The problem with 
> Joe Bag of Doughnuts installer is they fail to note the spacers and 
> O rings that go on the spindly threaded rods. Sky-tec threaded rods 
> are not as hard a steel as the Rotax and bend usually in shipment. 
> Ive had to straighten them and fab a new spacer to suit my liking to 
> get the gear length exactly the length of the other starter, which was 
> a waste of time. Simply reinstall the existing spacers and the clamp 
> and it works just fine.
>
> The Rotax heavy MX manual shows the spacers, O rings and clamp. That 
> rear clamp will keep the starter securely fastened preventing the 
> somewhat soft threaded rods from worrying you about a sagging starter.
>
> You just have to work around the ring mount, footwell, and any 
> hose/electrical routings with cold fingers getting it all back into 
> place without pulling apart. The O rings help but I find using safety 
> wire to hold the starter nose and tail tight while installing prevents 
> the starters from falling apart on install which can damage brushes. 
> Once the starter starts to slip in place, and you have not forgotten 
> to put the clamp back on, simply cut the .020 safety wire off, and 
> push it home.
>
> I normally do starter changes and engine rubber mount changes at the 
> same time by pulling the engine on a 5 year. If you make the engine 
> easy to disconnect and come off like a pod, it is a 4 hour hose, 
> rubber, starter cleanup, and service rather than days of frustration.
>
> Best Regards,
>
> Bud Yerly
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for 
> Windows 10
>
> *From: *Martin Tuck <mailto:MJKTuck@cs.com>
> *Sent: *Wednesday, December 2, 2020 11:09 PM
> *To: *europa-list@matronics.com <mailto:europa-list@matronics.com>
> *Subject: *Re: Europa-List: Rotax 912ULS starter motor
>
> Nine years ago on the Rotax Owners Forum there was some commentary 
> surrounding the suitability of the Sky-Tec starter due to the lack of 
> oil seal resulting in oil in the starter and possibly compromising the 
> oil return system.
>
> This is explained in a Rotax service bulletin.
>
> See Rotax Service LetterSL-912-014 / 914-012 / 2ST-008 
> <https://eur05.safelinks.protection.outlook.com/?url=http%3A%2F%2Flegacy.rotax-owner.com%2Fsi_tb_info%2Fserviceletter%2Fsl-912-014-r3.pdf&data=04%7C01%7C%7Ce4413423f0a147ea925a08d897413630%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637425653619573178%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=7JH9LR5coDY%2FiHPA1jXP%2FaAdctWtKMibkk4lAEeCbYY%3D&reserved=0>for

> more information.
>
>
> That was a while ago and put me off the idea of using that starter.
>
> Do you know if the Sky-Tec starter has since been modified to prevent 
> this? It doesn't sound like those who have used it have had issues 
> like this.
>
> Thanks,
> Martin Tuck
> N152MT
> Wichita, Kansas
>
> On 12/1/2020 7:16 PM, Bud Yerly wrote:
>
>     Arwel,
>
>     In my Troubleshooting guide I mention the starter issues.
>
>     It is my opinion all Rotax engines should upgrade to the high
>     torque starter.
>
>     Ive tried them both. The Rotax high torque is what I
>     installed ($1100USD), mainly because my plane was kept stock as
>     much as possible. For the Experimenter I recommend the Sky-Tec
>     as it costs half (<$500 USD) as much and is quite torquey.
>
>     
>
>     Both spin the prop with authority, easily surpasses the ignition
>     excitation speed. With plugs in and ignition off, I see 500 RPM
>     for a 914/912 and 400-450 for a 912S/iS.
>
>     Even with a slightly low battery, starts are crisp. This
>     lengthens the life of the sprag clutch. But these clutches do
>     wear and somewhere within 1000 hours even on a well maintained
>     912S engine with good starting, it may fail.
>
>     
>
>     In my Rotax troubleshooting update in March, I went into the soft
>     start/starting ignition problems of the Rotax. As many have
>     learned, once the starter cant push past the compression peak
>     at ignition, the engine will kick back which will quickly wear the
>     sprag clutch. What I didnt explain completely was when the
>     sprag clutch begins to weaken and slightly slip, this will
>     exacerbate the kickback issues. Adding a high torque starter on
>     a defective clutch will not be the total answer to the
>     kickback. Because the Rotax sprag clutch is a trapped un-round
>     roller type one way clutch, if the spring that holds the un-round
>     roller in place is loaded excessively, the spring stretches which
>     causes the clutch to slip so it no longer is an effective one way
>     clutch. The good news is there is no damage to the starter or
>     the crank shaft when this happens unless the engine continues to
>     have kick backs with the defective clutch, then things break
>     and fowl the engine with metal parts. Which means it goes from a
>     somewhat expensive repair to a very expensive repair. Youtube has
>     videos on the different types of these one way clutches.
>
>     
>
>     I recommend that if you have an XS firewall forward (with the ring
>     mount) the high torque starter will fit. (Note the Rotax high
>     torque may come with the tabs still attached which must be
>     cut/ground off. Our dealers in the States supply them ready to
>     install without the tabs.) I found the Sky-Tek to be well built
>     and spun up quickly on some light sport aircraft we have around
>     here. I think it is good insurance for preserving the sprag
>     clutch. The Sky-Tek is cheaper also.
>
>     
>
>     For those with the Classic FWF, Im afraid neither of the high
>     torque starter options will fit the original Classic mount. It
>     is too long by only a few millimeters, but it is too long.
>     Service your starter for good operation, keep the battery up, and
>     on very cold starts, use engine preheat.
>
>     
>
>     Best Regards,
>
>     Bud Yerly
>
>     www.customflightcreations.com
>     
> <https://eur05.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.customflightcreations.com%2F&data=04%7C01%7C%7Ce4413423f0a147ea925a08d897413630%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637425653619573178%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=HlvIQjpH42%2BEPZpJGxoIdhCla8JaEK1CDVxNtmV2E3s%3D&reserved=0>
>
>     Sent from Mail
>     
> <https://eur05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgo.microsoft.com%2Ffwlink%2F%3FLinkId%3D550986&data=04%7C01%7C%7Ce4413423f0a147ea925a08d897413630%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637425653619583173%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=uaUpZqhiF2nGrXR5s9Ou%2BjJ927NGj4zzU6x5YVH0m20%3D&reserved=0>
>     for Windows 10
>
>     
>
>     *From: *arwel pritchard <mailto:arwel.pritchard@powercom.ltd.uk>
>     *Sent: *Tuesday, December 1, 2020 8:51 AM
>     *To: *europa-list@matronics.com <mailto:europa-list@matronics.com>
>     *Subject: *Europa-List: Rotax 912ULS starter motor
>
>     
>
>     Good morning
>
>     
>
>     Has anybody replaced the starter motor on a 912ULS with a Sky-Tec
>     model. Apparently, it cranks the engine faster than the standard
>     Rotax model.
>
>     I have been quoted 660 for this unit, seems quite expensive,
>     but if it preserves the sprag clutch (which I had to replace last
>     year at much more cost) its got to be a good thing?
>
>     Just wondering if its worth it.
>
>     
>
>     
>
>     
>
>     
>
>
> -->
>



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