---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Tue 12/01/20: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:42 AM - Rotax 912ULS starter motor (arwel pritchard) 2. 06:38 AM - Re: Rotax 912ULS starter motor (Alan Burrill) 3. 05:18 PM - Re: Rotax 912ULS starter motor (Bud Yerly) ________________________________ Message 1 _____________________________________ Time: 05:42:12 AM PST US From: arwel pritchard 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. ________________________________ Message 2 _____________________________________ Time: 06:38:30 AM PST US From: Alan Burrill Subject: Re: Europa-List: Rotax 912ULS starter motor I=99ve just replaced the sprag clutch at 700hours and already have the sky-tec fitted for at least 500hours of those. Alan Sent from my iPhone > On 1 Dec 2020, at 13:49, arwel pritchard wrote: > > =EF=BB > Good morning > > > > Has anybody replaced the starter motor on a 912ULS with a Sky-Tec model. A pparently, it cranks the engine faster than the standard Rotax model. > > I have been quoted =C2=A3660 for this unit, seems quite expensive, but if i t preserves the sprag clutch (which I had to replace last year at much more c ost) its got to be a good thing? > > Just wondering if it=99s worth it. > > > > > > > ________________________________ Message 3 _____________________________________ Time: 05:18:10 PM PST US From: Bud Yerly Subject: RE: Europa-List: Rotax 912ULS starter motor Arwel, In my Troubleshooting guide I mention the starter issues. It is my opinion all Rotax engines should upgrade to the high torque starte r. I=92ve tried them both. The Rotax high torque is what I installed ($1100US D), mainly because my plane was kept stock as much as possible. For the Ex perimenter 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 40 0-450 for a 912S/iS. Even with a slightly low battery, starts are crisp. This lengthens the lif e of the sprag clutch. But these clutches do wear and somewhere within 100 0 hours even on a well maintained 912S engine with good starting, it may fa il. In my Rotax troubleshooting update in March, I went into the soft start/sta rting ignition problems of the Rotax. As many have learned, once the start er can=92t push past the compression peak at ignition, the engine will kick back which will quickly wear the sprag clutch. What I didn=92t explain co mpletely was when the sprag clutch begins to weaken and slightly slip, this will exacerbate the kickback issues. Adding a high torque starter on a de fective clutch will not be the total answer to the kickback. Because the R otax 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 s pring stretches which causes the clutch to slip so it no longer is an effec tive 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 =93k ick backs=94 with the defective clutch, then things break and fowl the engi ne with metal parts. Which means it goes from a somewhat expensive repair t o a very expensive repair. Youtube has videos on the different types of the se one way clutches. I recommend that if you have an XS firewall forward (with the ring mount) t he 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, I=92m afraid neither of the high torque sta rter 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 operat ion, keep the battery up, and on very cold starts, use engine preheat. Best Regards, Bud Yerly www.customflightcreations.com Sent from Mail for Window s 10 From: arwel pritchard Sent: Tuesday, December 1, 2020 8:51 AM Subject: Europa-List: Rotax 912ULS starter motor Good morning Has anybody replaced the starter motor on a 912ULS with a Sky-Tec model. Ap parently, it cranks the engine faster than the standard Rotax model. I have been quoted =A3660 for this unit, seems quite expensive, but if it p reserves the sprag clutch (which I had to replace last year at much more co st) its got to be a good thing? Just wondering if it=92s worth it. ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message europa-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Europa-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/europa-list Browse Digests http://www.matronics.com/digest/europa-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.