# Cuyuna 430 > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Cuyuna_430 > Markdown URL: https://mediated.wiki/source/Cuyuna_430.md > Source: https://en.wikipedia.org/wiki/Cuyuna_430 > Source revision: 1349525837 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Cuyuna 340 & 430 Type Two-stroke aeroengine National origin United States Manufacturer Cuyuna Development Company First run 1979 Major applications Pterodactyl Ascender The **Cuyuna 430** and **Cuyuna 340** are a family of two-stroke, twin-cylinder piston [snowmobile](/source/Snowmobile) engines that were redesigned to serve as [ultralight aircraft](/source/Ultralight_aircraft) powerplants.[1][2] ## Development While developing the [Pterodactyl Pfledge](/source/Pterodactyl_Ascender) flying wing ultralight in the late 1970s, designer Jack McCornack experimented with a number of possible engines. Early flights used a German-made Sachs engine, but the high exchange rate and long lead times for this engine convinced him to try other options.[2] McCornack settled on a [snowmobile](/source/Snowmobile) engine produced by the [Cuyuna Development Company](/source/Cuyuna_Development_Company) as having the best potential. In 1979 he modified the engine with a [crankcase](/source/Crankcase) extension, an additional main bearing, lowered the [compression ratio](/source/Compression_ratio) using an additional head gasket and substituted a smaller 32 mm (1.26 in) Mikuni [carburetor](/source/Carburetor), amongst other modifications. The original snowmobile engine produced 40 hp (30 kW). Lowering the compression ratio not only de-rated the engine, but also made pull-starting easier and allowed it to run on lower-[octane](/source/Octane) [regular auto fuel](/source/Avgas#Automotive_gasoline). The resulting engine worked well, was de-rated to produce 30 hp (22 kW) at 5,500 rpm and proved reliable in service.[2] Citing liability concerns over producing a two-stroke engine for human-carrying aircraft applications, Cuyuna declined to produce the modified engine. Instead, Cuyuna decided that the resulting engine was different enough from the base snowmobile engine that they would supply assembled and test-run shortblocks as parts to McCornack's company, *Pterodactyl Limited*, who would then complete the engines and be the manufacturer, allowing Cuyuna to continue producing snowmobile engines.[2] After two years of poor sales of snowmobiles, due to a dearth of snow and no lawsuits against Pterodactyl Limited regarding the engine, Cuyuna agreed to build the engines themselves.[2] The 430 was also produced in a reduced 2.362 in (60.0 mm) bore version called the 340. The modification reduced its displacement to 339 cc and output to 25 hp (19 kW) at 5500 rpm. The standard 430 has a bore of 2.658 in (67.5 mm).[1] ## Variants **340D** - Direct drive version, 25 hp (19 kW) at 5500 rpm, [recoil starter](/source/Recoil_starter).[1] **340R** - Reduction drive version using a belt drive system, 25 hp (19 kW) at 5500 rpm, recoil starter[1] **430D** - Direct drive version, 30 hp (22 kW) at 5500 rpm, recoil starter.[1][2] **430F** - Reduction drive version using a 3:1 gearbox system, dual carburetors, producing 45 hp (34 kW).[3] **430R** - Reduction drive version using a belt drive system, 30 hp (22 kW) at 5500 rpm, recoil starter[1][2] **UL II** - 35 hp (26 kW) version ## Applications - [Advanced Aviation Cobra](/source/Advanced_Aviation_Cobra) - [Advanced Aviation Husky](/source/Advanced_Aviation_Husky) - [Airborne Avenger](/source/Airborne_Avenger) - [Airmass Sunburst](/source/Airmass_Sunburst) - [American Aerolights Eagle](/source/American_Aerolights_Eagle) - [Chandelle Mk IV](/source/Chandelle_Mk_IV) - [Eastern Ultralights Snoop](/source/Eastern_Ultralights_Snoop) - [Fletcher Hercules](/source/Fletcher_Hercules) - [Goldwing Ltd Goldwing](/source/Goldwing_Ltd_Goldwing) - [Goodwin Tri-Moto](/source/Goodwin_Tri-Moto) - [Hovey Delta Bird](/source/Hovey_Delta_Bird) - [International Ultralite Banchee](/source/International_Ultralite_Banchee) - [Kolb Ultrastar](/source/Kolb_Ultrastar) - [LEAF Trike](/source/LEAF_Trike) [Malibu Grand Prix Virage open wheel kart w/ CVT belt drive](https://en.wikipedia.org/w/index.php?title=Malibu_Grand_Prix_Virage_open_wheel_kart_w/_CVT_belt_drive&action=edit&redlink=1) - [Manta FX-3](/source/Manta_FX-3) - [Meadowlark Ultralight Meadowlark](/source/Meadowlark_Ultralight_Meadowlark) - [Mitchell Wing P-38](/source/Mitchell_Wing_P-38) - [Pinaire Ultra-Aire](/source/Pinaire_Ultra-Aire) - [Pterodactyl Ascender](/source/Pterodactyl_Ascender) - [RagWing RW4 Midwing Sport](/source/RagWing_RW4_Midwing_Sport) - [Robertson B1-RD](/source/Robertson_B1-RD) - [Rotec Rally 2B](/source/Rotec_Rally_2B) - [Star Flight Tristar](/source/Star_Flight_Tristar) - [Swallow Aeroplane Company Swallow B](/source/Swallow_Aeroplane_Company_Swallow_B) - [Ultra-Fab Sundowner](/source/Ultra-Fab_Sundowner) - [Vintage Ultralight SR-1 Hornet](/source/Vintage_Ultralight_SR-1_Hornet) - [Waspair HM 81 Tomcat](/source/Waspair_HM_81_Tomcat) ## Specifications (430D) *Data from* Cuyuna[1] & McCornack[2] ### General characteristics - **Type:** Direct drive two-stroke piston aircraft engine - **[Bore](/source/Bore_(engine)):** 2.658 in (68 mm) - **[Stroke](/source/Stroke_(engine)):** 2.362 in (60 mm) - **[Displacement](/source/Engine_displacement):** 428 cc (26.11 cubic inches) - **[Dry weight](/source/Dry_weight):** 65 lb (29 kg) - **Designer:** McCornack/Cuyuna ### Components - **Fuel type:** [Regular auto fuel](/source/Avgas#Automotive_gasoline) - **Oil system:** 40:1 premixed fuel and oil - **Cooling system:** fan forced air ### Performance - **Power output:** 30 hp (22 kW) - **[Compression ratio](/source/Compression_ratio):** 12.5:1 - **[Power-to-weight ratio](/source/Power-to-weight_ratio):** 0.46 hp/lb (0.76 kW/kg) ## References 1. ^ [***a***](#cite_ref-Cuyuna_1-0) [***b***](#cite_ref-Cuyuna_1-1) [***c***](#cite_ref-Cuyuna_1-2) [***d***](#cite_ref-Cuyuna_1-3) [***e***](#cite_ref-Cuyuna_1-4) [***f***](#cite_ref-Cuyuna_1-5) [***g***](#cite_ref-Cuyuna_1-6) Cuyuna Development Company: *Cuyuna Engines*, Cuyuna Development Company, undated 1. ^ [***a***](#cite_ref-McCornack_2-0) [***b***](#cite_ref-McCornack_2-1) [***c***](#cite_ref-McCornack_2-2) [***d***](#cite_ref-McCornack_2-3) [***e***](#cite_ref-McCornack_2-4) [***f***](#cite_ref-McCornack_2-5) [***g***](#cite_ref-McCornack_2-6) [***h***](#cite_ref-McCornack_2-7) McCornack, Jack (Fall 1980). ["The Cuyuna 430D Experimental Aircraft Engine, Ptimes Vol 2 No 1"](https://web.archive.org/web/20110716123213/http://pterodactyl.squarespace.com/storage/ptimes/Ptimes%20Vol%202%20No%201.PDF) (PDF). Archived from [the original](http://pterodactyl.squarespace.com/storage/ptimes/Ptimes%20Vol%202%20No%201.PDF) (PDF) on 2011-07-16. Retrieved 2009-09-29. 1. **[^](#cite_ref-Cliche_3-0)** Cliche, Andre: *Ultralight Aircraft Shopper's Guide* 8th Edition, page D-17. Cybair Limited Publishing, 2001. [ISBN](/source/ISBN_(identifier)) [0-9680628-1-4](https://en.wikipedia.org/wiki/Special:BookSources/0-9680628-1-4) v t e 2si engines Aircraft engines 215 230 340 430 460 540 690 808 Multi Fuel Engines 215 MF 230 MF 460 MF Industrial Engines 215 230 460 690 Marine Engines & Jet pumps 460 690 Sport Vehicle Engines 460 500 540 --- Adapted from the Wikipedia article [Cuyuna 430](https://en.wikipedia.org/wiki/Cuyuna_430) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Cuyuna_430?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.