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ETLB Squawk Forums  /  miniMax, Hi-Max, and AirBike General Discussions  /  Industrial twins in a Airbike
Posted by: erkki67, February 19, 2023, 7:42am
Are there any examples of an Airbike equipped with an industrial twin engine? And how satisfied are you with the performance?
Rgds Erkki
Posted by: Cy V, February 19, 2023, 6:35pm; Reply: 1
To the best of my knowledge, I don't think anyone has ever put one of the v-twins on any of the Mini-Max airframes. I do think they would work (depending on power output). The guys at Hummel are now selling a v-twin they claim puts out 35-40 hp. That might get the job done on a Mini-Max.

https://www.youtube.com/watch?v=odOwW7uLzQA
Posted by: erkki67, February 24, 2023, 4:20pm; Reply: 2
There was at least one in Sweden that flew with a industrial v-twin!
Posted by: kenpowell, February 26, 2023, 3:07am; Reply: 3
I'm putting a B&S 993 in a 1600R.  I'll report details here when I get it running.
Posted by: erkki67, March 4, 2023, 6:10pm; Reply: 4
ken, what is your firewall forward system going to weight?
Posted by: raphael150, March 5, 2023, 8:13pm; Reply: 5
The guy who created the legal eagle is successfully using:

https://youtu.be/MBMAdLkYtz0
Posted by: erkki67, March 18, 2023, 4:24pm; Reply: 6
Hmmm, if this works in a Legal Eagle, then it might work in a Airbike as well!
Posted by: kenpowell, March 24, 2023, 2:44am; Reply: 7
Quoted from erkki67
ken, what is your firewall forward system going to weight?

I need to check-in more often.
Briggs and Stratton 993cc Direct Drive:
Bare Engine     68.6     
Carbs-VM32 (1.6 x 2)     3.2     
Exhaust (1.3 x 2)     2.6     
Oil (2.4 qts)     5     
Ignition- 2 coils, 2 HEI, 4 pickups, 2 switches     3.5     
Prop Flange     2.8     
Remove Governor     -0.73     
Crankshaft Taper to 1-7/16” adapter     1.1     
Camshaft Weight Loss     -0.43     
          
Total Engine Weight     85.64     
                    
Stock Cam     3.07     
DynoCam     2.64     
Difference     -0.43     
Governor     -0.73     
Weight Lost     -1.16     

Note that a redrive will add ~11.5 lbs.



Posted by: 437 (Guest), June 28, 2023, 2:46pm; Reply: 8
I need to check in more often as well.

Thank-you @Kenpowell for that information. I currently have a Hirth 2702 and plan to fly with it for a while. Since I have no love for 2-strokes I was thinking an industrial v-twin might be an "okay" engine for my 1700.

I'll try to find the video where a guy made a CHAIN PSRU. Certainly cheap and light, but not typical.
Posted by: erkki67, February 25, 2024, 12:23pm; Reply: 9
Hello Ken, do you have any new data available? rgds Erkki
Posted by: kenpowell, February 29, 2024, 2:56am; Reply: 10
I haven't touched the engine  (briggs 993cc) since summer.  I hope to get back to it and get it running sometime this summer.  I have to build the ignition system with 4 pickups, 2 HEI ignitions and 2 coils.  This allows hand-propping at 0 / TDC and running at 28 degrees BTDC.  The engine needs a separate ignition for each cylinder due to being a 90 degree 4-stroke plus separate pickups for 0 TDC and 28 degrees BTDC for each cylinder.  Sounds complicated but it really isn't.  The engine will be direst drive and will use an Eiffel prop to test for horsepower.
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