Wondering what the largest engine the Airbike can accommodate?  I have 503's   mainly...several Half Vw's also...Herb

Both the 503 and the half VW will work.  I had a half VW on mine and Airbike Ace uses a 503.

I figured that there were some airbikes out there with big engines...This one was destined for floats and a Kawasaki 440 water cooled engine.dcdi...Mated to a b box.  
  Sure should be a rocket with a 503.  Herb

I think an Airbike with a Pegasus O-100 engine would be awesome.

Does there exist an viable alternative engine for the 503, in terms of cost and reliability and other then Hirth?

Quoted from radfordc

Both the 503 and the half VW will work.  I had a half VW on mine and Airbike Ace uses a 503.

Do you have any close up picts on the 1/2 vw mount on your a/b. I have been interested for a while.

Monte

Quoted from erkki67

Does there exist an viable alternative engine for the 503, in terms of cost and reliability and other then Hirth?

Yes - this one: http://www.compactradialengines.com/mz201.html or even better: http://www.compactradialengines.com/mz202.html

wouldn't mind a pegasus on my Hi Max myself.

The Hirth F-23 50hp is a great engine for the Airbike.  I just completed the installation, replacing the Rotax 447, and I really like the switch.  10 more hp, electric starter, a lot smoother engine since the F-23 is horizontally opposed, and I'm getting better fuel economy, too.  I was able to use the same square mounting bar I had for the Rotax, ordered the F-23 for the inverted mounting, and just had to make a few other mounting alterations.  You'll need a Right Turning propeller now for the new engine. I put on a compression type swivel tailwheel from Aircraft Spruce, which I like a lot better than the original tailwheel, too.  Engine break in was simple.  Confirmed weight and balance by adding some weight in the rear, and I've got 10 hrs flying since the end of May.  Highly recommend going with the F-23.
Jeff

Hi Jeff,

   What is the AS/S part number for the tailwheel that you bought ?


    Ted

Hi Ted,
The tailwheel is PN 06-00399 and the compression kit is 05-11458.

Has anyone used a Rotax 582 on an Airbike tandem. Can this be done?

I'm still planning my build but want to keep an eye open for a secondhand engine, there seems to be the occasional one of these in my neck of the woods.

That is good information Jeff, thanks for posting. Where are you located?  I am 10 miles south of Wichita, KS.  

Paul Fiebich

The Wankel Engine of Geiger might be a solution 50hp at 100lbs.

Quoted from erkki67

The Wankel Engine of Geiger might be a solution 50hp at 100lbs.

But the MZ201 is 45hp for 69lbs complete. Or the MZ 202 is a genuine 60hp for 87lbs complete with proper gearbox, both inc. electric start. And at comparable prices to the F23.

Quoted from TreeTopsTom

That's a LOT of exhaust components! (and I wondered about the weight of it all.

78lbs, including reduction unit, full exhaust, and electric start or 71lbs with recoil start reduction unit and full exhaust   http://www.recpower.com/F-23%202%20cycle%2050hp.htm

Hey Jeff what seat are you using. Like to install one on my a/b.

Monte

If you shortened the exhaust pipes and brought the mufflers right up to the bottom of the fuselage it would look good.

2-stroke exhausts are nearly always a tuned length. The distance between the exhaust port, and whatever part of the muffler system acts as a rear cone, has a big influence on the rpm at peak torque.

So you'd really need a dyno to test the effect of varying the 'downpipe' length.

I have to say Jeff's pipes look very long compared to most.

Bruce

http://www.recpower.com/images/f23/F23-BeLite.jpg
Here is pict of a f-23 on a belite showing I assume the stock exhaust. looks like the mufflers on your a/b are stock but someone has added an extension. this will change the pulse timing of the engine which probably will result in torque curve change. IMHO.

monte

You're right, the original mounting didn't have the right length and the exhaust looked terrible.  Fortunately, I quickly found a good custom muffler guy who welded to spec so the pipes are tuned and without all the springs.  The F-23 motor has a lot of different exhaust options, but the only one that really works with the Airbike is the straight down and 90 deg bend.  Looks and performs as it should now.  I'd really prefer a 2 into 1 curved setup like Tom's Zenoah exhaust in the pic above, but they're not made by Hirth for the F-23, as far as I can tell.  Anyone know of someone who can make a correctly tuned setup?  
Here's a recent pic of the Airbike, and I'm attaching the pdf of the F-23 exhaust options.

Tom, the original pipes that came with the motor were a curved configuration, so had to be straightened to fit the Airbike.  The first guy I took them to didn't follow instructions, and made the frankenstein exhaust in the first pics (too long, too many pieces).  Then I found a guy that made them to the Hirth drawings, and with the right length, they are tuned.

One more for the pot! Just been looking at the Verner Radial engines (mmm!) they do a 3 cylinder radial 4 stroke, 42hp, 90ft lbs of torque at 2100rpm (twice the torque of a 447) and weighing in at 73lbs. UK price is 6000 euros.

http://www.vernermotor.com/3VW.html

here is a video of the 3vw. It sounds as good as it looks. I bit pricey.
https://youtu.be/32hhwjAFg5w

Monte

https://youtu.be/Oep0IlURHck and here it is doing what it's meant for!

You would think these engine manufacturers would offer a tuned exhaust suitable for use on a lightweight application. the old 2 stroke motorcycles had the best exhaust systems for extraction of power and if you researched one of equal displacement to the engine you were tuning most likely the manufacturer has specs. for the fabrication of a performance system. As an old hobby racer exspansion chambers could be tuned for different power curves, peak horsepower and torque. For peak horsepower , say 40 h.p. at 5800 to 6400 rpm or you can alter the chamber and get 35 h.p. from 3500 to 6000. Most motorcycles were tuned for a happy medium between peak h.p. and a decent torque curve. Your best bet would be Yamaha, Kawasaki, Suzuki, Bultaco, Montesa, CZ, any factory sponsored racing machines would have specs and drawings for what you are looking for. Bill Wurges was a prominent after market supplier of 2-stroke exhaust systems years ago and there are still some others around. You would have to adjust your jetting and maybe the heat range on plugs, but for optimum performance this would be the route to take.

You would think these engine manufacturers would offer a tuned exhaust suitable for use on a lightweight application. the old 2 stroke motorcycles had the best exhaust systems for extraction of power and if you researched one of equal displacement to the engine you were tuning most likely the manufacturer has specs. for the fabrication of a performance system. As an old hobby racer exspansion chambers could be tuned for different power curves, peak horsepower and torque. For peak horsepower , say 40 h.p. at 5800 to 6400 rpm or you can alter the chamber and get 35 h.p. from 3500 to 6000. Most motorcycles were tuned for a happy medium between peak h.p. and a decent torque curve. Your best bet would be Yamaha, Kawasaki, Suzuki, Bultaco, Montesa, CZ, any factory sponsored racing machines would have specs and drawings for what you are looking for. Bill Wurges was a prominent after market supplier of 2-stroke exhaust systems years ago and there are still some others around. You would have to adjust your jetting and maybe the heat range on plugs, but for optimum performance this would be the route to take.

That Verner 3 cylinder radial would look and sound pretty good on the Airbike.  Will have to research it (weight, mounting, prop, etc).  Here are a few recent pics of my plane with the F-23 and properly tuned exhaust.  I did learn from the Hirth dealer that a 2 into 1 exhaust system had been tried, but just doesn't work that well because both cylinders of the F-23 fire at the same time.

Think I'm In LUVE!

Hey Texas Buzzard the seat looks to be off a quicksilver you can get from Air Tech Inc.