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Some Alternative Ultralight Single Cylinder Engines!

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Armilite

Well-Known Member
Joined
Sep 5, 2011
Messages
3,738
Location
AMES, IA USA
Was looking on eBay for some engine parts and stumbled on a NOS Head for and Old Sachs SA340SS Single Cylinder. Had (4) hole bolt pattern like the Rotax's, so got me looking at some Sachs Engines. Now at one time, there were over 500 different Brand Name Snowmobiles in the World that used about 20+ different Brand Name Engines. They all made many different CC Singles, Twins, Triples, and even some Quads.

2 Strokes can be hung upright or upside down. As far as I know, not many Ultralights or Kitplanes were designed to use one upside down, Challengers and T-Bird I's(277UL) was some that did. The Rotax 185UL(9.4hp) & 277UL(26hp) had a (4) Bolt Pattern on the PTO Case to attach the Rotax Gear Drive or an aftermarket Belt Drive.

Some, but not all Old Snowmobile Singles also have some different 4-6 Bolt Hole Patterns, so could be Adapted for Ultralight use. Some early 60's Skidoo/Rotax 247/250's also had the same (4) PTO Cover Threaded Holes. Some Sled motors, on some Brands had 2-3 different Class's. Like Skidoo/Rotax had a Standard 335 Single (78mm x 70mm) 334.6cc with 9.0cr, 30mm Carb and a Muffler was rated 20hp@5500rpms, a 340 TNT(78mm x 70mm) 334.6cc with 10.5cr, 38mm Carb and a Big Tube Muffler was rated 26hp@6500rpms, and a Blizzard 340(78.5mm x 70mm) 338.9cc rated 36hp@??00rpms, with ??cr(Thinking 11.8) and used a Tuned Pipe, no one seems to know what Rpms they were rated at, but I'm thinking 7500rpms as some others were at the time. The TNT & Blizzards used the same better design Ported Cylinder for Higher Rpms.

So basically they play with the Rpms used, Carb Size used, CR used, and Muffler/Tuned Pipe used to make different HP Classes of Engines.

A Sachs SA370(79mm x 75mm) 367.8cc, average used Price Range $50 to $200. Notice CR differences, Rpms used, Carb Size used, all three used a Muffler!

Some have Electric Start Option.

340 22hp@5250rpms 38mm Carb 9.0cr with a Muffler!

340SS 26hp@6000rpms 38mm Carb 11.0cr with a Muffler!

370 23.5hp@5250rpms 30mm Carb 9.7cr with a Muffler!

PDF Manual with some Spec's.
http://www.vintagesnow.com/Engine_manuals_files/1969_Sachs_SM_Pt2_SM.pdf

There is a very good book that shows most of these Old Engine Spec's and gives a lot of good Info. For some, it even gives Racing Cylinder Porting Data.

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Attachments

  • SACHS 340 ENGINE SPEC'S.jpg
    SACHS 340 ENGINE SPEC'S.jpg
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  • SACHS 340 PTO SPEC'S 3.jpg
    SACHS 340 PTO SPEC'S 3.jpg
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  • 1970 Sach SA370 Single Cylinder Snowmobile Engine 79mm x 75mm 368cc.jpg
    1970 Sach SA370 Single Cylinder Snowmobile Engine 79mm x 75mm 368cc.jpg
    19.3 KB · Views: 17
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