I know this is an Old Post, but I want to add my 2 Cents! Almost ALL Rotax UL Engines, except the 185UL are based off the Skidoo/Rotax Core Engines! The Rotax 185 was used on Water Pumps, Weed Wackers, Generators, I have seen reference to them being used in Europe on some Sleds, But I have never seen any photo's of one used that way. Water Pumps was Rotax's Oringal Core Business. Skidoo/Rotax Engines started in 1963 and went from Bosch Points to Nippon Denso CDI around 1983. All Rotax 277UL Free Airs rated 26hp@6250rpm were Points Engines till discontinued around 2000, but could be converted to Nippon Denso CDI. Most of these Points to CDI Conversions were done by Air Screw and few other Big Ultralight Dealers. There was also a 277UL Fan engine used on SCAT HOVERCRAFT that was all Nippon Denso CDI and was rated 28hp@6400rpm. Rotax wanted to make their UL Engines with Dual Plug Ignition and Nippon Denso didn't want anything to do by then with Airplanes, so around 1993 about 10 years later Skidoo/Rotax and Rotax UL Engines were Switched over to Ducati CDI Dual Ignition for their UL Line of engines and the Skidoo/Rotax line of engines to Ducati Single Ignition. Around late 1992, 1993 is also when the Provision 8 Cases came out. The 670(Big Dog) actually came out in late 1992 in limited numbers and had a Crank Issue, it was corrected for the 1993 Model, and is also what Helped kill off the 617/618UL. The 583 was and still is a very Popular Engine as is the 670. 1993 was a very Important year for SKIDOO/BRP/Rotax, that is also WHY the 670 the last Provision 8 Engine made was never made into a UL Engine account that is the first year Rotax offered their New Golden Boy the 912 (80hp) which Cost about $4-5000 more than their 618UL(74.3hp@6750rpm). People would not have spent that much for just 5-6hp and more Weight than the 618UL made, and the New 670(Big Dog) Blew Both the 618UL and the 912UL out of the water, since it could make 95hp@6500rpm!
Rotax UL Motors don't really used a Tuned Pipe, they use more of a Tuned Muffler that is Tuned for the Sound Signature! Most UL Engines are rated at 6500rpm, the 618UL was rated at 6750rpm, the 185UL was rated at 5000rpm. The same Motors used in Sleds, Fanners are usually rated at 7000-7500rpm, Liquid Cooled(LC) at 7750-8000rpm.
A Skidoo 277F = Rotax 277UL. There is a difference in the 277 Case's around the PTO if you want to run a Gear Drive and around the Stator area if you want to make it into a Free Air. Some 277 Case's are drilled for both Bosch Points or Nippon CDI. 277UL with an R&D tuned Pipe. http://www.rotaxservices.com/dyno.html#7
A Skidoo 377F/380F = Rotax 377UL. All 377UL's were Single Ignition.
A Skidoo 440F = Rotax 447UL. 447UL with an R&D Tuned Pipe. http://www.rotaxservices.com/dyno.html#15
A Skidoo 500F/503F = Rotax 503UL. A 503UL with an R&D Tuned Pipe. http://www.rotaxservices.com/dyno.html#7
A Skidoo 463LC & 470LC = 462UL. Wasn't a very popular Sled or UL Engine for either side. 463cc, HP vs Weight.
A Skidoo 521LC = 532UL. The 521/532UL was also dropped around 1991/92 that is why most are Pro4.
A Skidoo 580/582, and 583(RAVE) = 582UL. A 582UL with an R&D Tuned Pipe. http://www.rotaxservices.com/dyno.html#3 So your talking 97hp@7750rpm with a Tuned Pipe for the Sled Engine vs 65hp@6500rpm with a Muffler for Airplane use.
A Skidoo/Rotax 583 with an R&D 618 Tuned Pipe. http://www.rotaxservices.com/dyno.html#583
A Skidoo/Rotax 617LC = Rotax 618UL. 618UL with an R&D Tuned Pipe. http://www.rotaxservices.com/dyno.html#1
A Skidoo/Rotax 670 with an R&D 618 Tuned Pipe. http://www.rotaxservices.com/dyno.html#89
There was only one Provision 8 Triple I believe 738/748
Almost ALL Skidoo/Rotax's Liquid Cooled used 11.5cr, except the 380HO(11.2cr) & 670HO(12.5cr). I have seen Documentation of some 532UL's also used 12.5cr, but most were also 11.5cr. I have never found any reference to a 521HO. 380HO's 11.2cr Stock 48hp@7000rpm were only Sold in Alasaka and Euroupe! With a better Tuned Pipe Dynoed 57.26hp@7000rpm, it still made around 52hp at 6500rpm!
Some General Rules for 2 Strokes. A +/- 1.0cr = 2hp, so a +/- 0.5cr = 1hp. At 6500rpm(Industry Standard today) and using 11.5cr with a Good Tuned Pipe it takes on Avg 7cc to make 1hp! Fresh 91 Octane is good for 11.8cr or Cranking 175psi. If you look at all the different Engines Companies today, most have dropped the CR to 9.5cr for most of their Engines used on Planes today, Hirth, Simonini, MKz, etc. Atmospheric Pressure is 14.7 at Sea Level. 14.7 x 11.8cr = 173.4psi, if your Engine was Built Perfect, but most Engines aren't. The Higher you go, or start out at, that 173.46psi Number will be Smaller, as your Max HP will drop the Higher you go or start out at. Avg PSI Drop is about 3% for every 1000ft. 9.6cr x 14.7 = 141.1psi. Fresh 87 Octane is Good for around 125-130psi. Pump Gas can lose 2 Points in Octane in as little as 2 weeks. Go Bad in 6 months. 100LL has a 5 Year Shelf Life.
532UL 11.5cr 64hp@6500rpm 521cc/7cc = 74.2hp@6500rpm is possible!
582UL 11.5cr 65hp@6500rpm 580cc/7cc = 82.8hp@6500rpm is possible!
618UL 11.4cr 74.3hp@6750rpm 617cc/7cc = 88.1hp@6500rpm is possible!
670 11.5cr 669cc/7cc = 95.5hp@6500rpm is possible! A Rotax Rick 670 Dynoed 93hp@6350rpm!
So YES, a Skidoo 583 can make you a Nice Engine for an Airplane. With Fresh 91+ Octane Gas and a Good Oil you can turn them Higher rpm, but the Service Life will go down. Rotax Service Life has more to do with WHO is Maintaining and Flying them, than Rpm used. 11.5cr is on the Edge with 91 Octane for Detonation, so run 93 or 100LL. With Higher Rpms you also make more Friction Heat & Hp Heat that you have to deal with. Can it be done, Yes, if you Design and Build it right. It's better to keep rpms down to Max 6500rpm and use a Tuned Pipe, and Higher CR if below 11.5cr, or use more CC to make more HP. Look what Rotax Rick does to make his 670's have a 450hr TBO, use 40:1 Amsoil Interceptor Oil premixed, Ceramic Top Coated Pistons, use's 6350rpm. With the 582UL Exhaust Muffler a 583 will make around same 65hp@6500rpm. With a Good Tuned Pipe it will make more HP at same 6500rpm! The 583, 670 were discontinued after 1999 when Skidoo came out with their New 2000 Line of Engines. The 521 was dropped in 1993, as was the 617. The 503 was dropped in 2003 by the introduction of the 550F, hence we never got a 550UL either. The 277F, 380F, 440F weren't dropped till around 2008 by Skidoo. I believe the 277UL was dropped around late 90's. Some of these Skidoo/Rotax Engines, 250F, 377F, 440F, 503F, 550F are still being made in Russia under the Brand Name RMZ!
That RMZ-250 Single(Skidoo/Rotax) 51,500 rub = $739.52 usd, is 22hp@6500rpm with a Muffler. Around 32-34hp with a Good Tuned Pipe! (72mm x 61mm) 248.5cc/7cc = 35.5hp is possible. Use's a 34mm Carb vs a 36mm.
IF, you notice, their RMZ-250F, RMZ-500F and RMZ-550F all have Provision 8 Case's, our 550F's Sold here US/Canada is not Pro8 on the Top Case Halve, but is on bottom Case! A fellow I talked to along time ago said he had his 2004 550F with 34mm Carbs and it Dynoed 70hp@7000rpm using 9.6cr! Newer 550F's Sold here in US/Canada now only have 30mm carbs and are rated 58hp@6800rpm. 550F(76mm x 61mm) 553.6cc/7cc = 78.6hp is possible. Hmmm, wouldn't sell many 582UL's with all that extra Weight & Cost for Cooling if we had a 550UL now would they. RMZ-550 Engine 89,000 rub = $1,364.62 usd, 93,000 rub = $1,425.89 usd, 96,000 rub = $1,472.00 usd in todays $$$. A 582UL Engine only today is around $5200 + Cooling.