Hirth versus Rotax, comparing Hirth and Rotax aircraft engines, which is the better engine for ultralights?

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Hirth vs Rotax.

Scrivner vs Loveman 

U. B. Judge 

The following was posted at ul_flyer.com, it deals with a recommendation I made in response to advise given by Mr. Chuck Scrivner to an ultralight pilot. Mr. Scrivner gave a recommendation for the pilot to consider a Hirth engine.

I responded that I felt the Rotax was a better choice. Mr. Scrivner then responded with the following. Which of course I responded to, unfortunately when using the reply message board, I do not have access to a word processor, to correct spelling etc. and it is very difficult to make your answers flow right when you have to keep jumping back and forth from the question or reply to what you are writing.

Since there are issues here that should be dealt with I have decided to do a page on my site at www.ultralightnews.com - and use it to reply in a way where the answers and questions can be followed from point A to Z. So here goes.

Hirth Engines / Rotax

Mr. Chuck Scrivner
Hirth provides 1 year warranty...Rotax gives 6 months

A:Has anyone ever tried to get warranty out of Hirth? The last time I tried contacting what was suppose to the North American distributor he was no longer in business. Then I tried to contact the U.S. distributor, he referred me to the factory. The factory replied that (at that time) they did not recognize any North American distributor, would not honor any warranty claims or honor deposits taken for engines by anyone in North America. This was also written up in the U.S. Aviator published by Jim Campbell.

Mr. Chuck Scrivner
Hirth has 1000 hr TBO .....Rotax 350 hr

A:My reply was that I haven't seen a Hirth engine with 1,000 hrs on it. That all the ones I have worked on to date have either seized up or broken crankshafts in less than 100 hours. So the question is what difference does it make if someone says they can do something - prove it!

Mr. Chuck Scrivner
It would do well to site specific instances of stated malfunctions and correct info for the betterment/safety of the sport. To state blindly that no Hirth engine has ever gone more than 100 hrs stretches credibility.

A:First I did not say "no Hirth" I said none of the ones that I have worked on. You asked for specifics - here are some specific instances gleamed from another website, that is independent from me and has nothing to gain.

Rotax 503 versus Hirth 2703
Two-place builders almost invariably put a 503 of some vintage on their birds. But more and more, you'll spot C-2's and C-2S's sporting that square little Hirth. Now, Hirth claims a TBO of 1000 hours, a built-in starter, and more power-to-weight on their 2703 than Rotax can put out. On the negative side, there's the cost, fewer maintenance centers, and the usual horror stories about "them damn Hirths siezin' up when ya mount 'em upside-down". Personally, I know two pilots who made unscheduled landings which were directly attributable to their 2703 powerplants.

"I have a Hirth 2703, 55hp, with dual carbs, dual CDI ignition, and electric start. My engine has about 50 hours at present. I had a bad bearing which failed at seven hours.

"If you want to keep your Challenger in the air, buy a Rotax!! I've seen the Hirth quit several times on the Challenger and Hornet."

"A problem in operating Hirth engines is getting good factory support. The North American dealers in Canada do not provide good post-sale support. Good engine help can be obtained from Danny Day at CUA, Incorporated (1-602-961-3580). Danny is very good with all types of two-cycle engines. Also, Seneca Aircraft (U.S. Hirth dealer) is very helpful.

"Myself and two partners fly a C-2 with a Hirth 2703. We have a little over 80 hours on it and have not had any problems. The Hirth reps used our plane/engine for display at Arlington EAA fly-in for a couple of years, and they checked/adjusted everything with latest info. I don't know if this means a lot as most info has been made available to Hirth owners. If we get into the 250-300 hour range with no problems, I will be real pleased after hearing all of the 'bad' news. We are getting ready to put a set of Puddlejumpers on for next spring, and we are running the short re-drive. I'd like to find a tall re-drive from one of those that gave up on their Hirth."

"It all boils down to service, parts availability, and preference. Competition with Hirth has made the Rotax a better engine now, and we all benefit! If Hirth can correct the few problems that has plagued them we will have 2 good engines builders to choose from and again that will be good for ultralighters hopefully with lower prices. I fly with a Rotax 503 and it just runs better and better every time I go out. 3 years and 75hrs. on AMSOIL 100:1."

While in Evergreen, Alabama, I took time out to browse around the last day of the EAA Southeast Regional Fly-In (SERFI). One of the major players in the Challenger field was there, airing out a foot he recently injured in a wind shear-induced landing (I'll use his name later, if I can get his permission).
I asked about Hirths. Wish I hadn't. While I can't hope to duplicate the breadth and depth of his discontent with Hearths, here are few of his salient points:

  • The Hirth used in the Challenger is the 2703, a souped-up version of the smaller model 2704. The stress of pulling more HP out of the smaller engine force it to have a shorter lifespan.
  • Parts and service have always been the dickens to get, especially under warranty. Some of his customers bought new Hirths, needed warranty work, and were told "no" when they sent them in to be repaired by a major US dealer. The Hirth company then leaned on the owner of that dealership, and he relented. A substantial waiting period, however, was appended to all engines not bought directly from him.
  • Danny Day sold and serviced Hirths for awhile, but now he doesn't like them, either.
  • The big selling points on the Hirth were the built-in starter and the gearbox, but the higher price nullified any advantage the Hirth enjoyed.
  • Challenger will sell mounting kits and redrives for the Hirth, but they no longer offer the Hirth as an option.
  • He knew lots of flyers who disposed of their engines or their planes as a direct result of problems they were having with the Hirth.
  • 1000 hour TBO is a dream. Most are overhauled between 150 and 350 hours.

I built and flew a Challenger Clipped Wing Special until August of 1994 when my Hirth 2703 single CDI ignition motor stopped on final approach. It had 103 hours on it. I stretched the glide as far as I could but I hit the last house between me and the airport .If anyone purchased a new Hirtch motor from the manufacturer, or a distributor before August 1994, please contact me.

Naaa. Hirth won't make a hundred hours without trouble Hirth CLAIMS 1000 hr TBO , NEVER HAPPEN , not in this LIFETIME !!!!! When a Hirth blows it really BLOWS , then scream warranty HA ! then try and BUY parts HA again ! when customers send me Hirth engine to work on i require them to get there own parts , lotsa luck BTW try $ 169. for just a piston !!!!

Steve Airscrew Performance

Don Zank: "Re: UL: Hirth 2703 Engines" I am just happy that I never sold a Hirth engine to a customer, and I did lose one, sale because I would not sell one. I also lost other sales because of failures during demo flights and waiting parts due to failures.

Now Stev of Airscrew Performance is not a Hirth or Rotax dealer, and Don Zank is not a Rotax dealer and sells Challengers.

Mr. Chuck Scrivner
Hirth uses chromoly crank ...Rotax doesn't.

A:What difference does it make the Hirth has a chromoly crank - when the cranks breaks, as they do on a regular basis it still has to be repaired or replaced.

Mr. Chuck Scrivner
Hirth max CHT is 535 to 625 F ..Rotax is 450 or so.

A:Again what difference does it make what the CHT limits are - the Rotax is suppose to run as are Hirth engines at 350 EGT. If the Hirth is able to run hotter it just means you are going to due more damage when it finally goes. A lot like continuing to try to run with a broken leg.

Mr. Chuck Scrivner
Hirth cylinders are Nikasil ...Rotax cast iron

A:The Nikasil cylinders can't be rebored only replaced, the cast iron cylinders can be rebored at considerably less cost.

Mr. Chuck Scrivner
Hirths come with a starter ...Rotax is an add on

A:Since I couldn't argue with this I replied what difference does it make if the engines standard with an electric start if the engine is seized up on the ground. (If you can't beat them with brains baffle them with bullshit.)

Mr. Chuck Scrivner
Hirth is lighter wt.

A:That is debatable, and the published difference is not going to be noticed on a two place plane

Mr. Chuck Scrivner
A 65 hp Hirth is 625cc ...Rotax 65hp 582 is 580.7cc

A: Missed the point on this one - it appears that the Rotax produces the same power with less cc's.

Mr. Chuck Scrivner
Hirth delivers 65hp @ 6200rpm with more torque at the midrange
Rotax delivers 64hp @ 6500rpm (look at the power band charts!)

A: I responded that it is fine to have something published on paper - but the true test is in the field. My experience with both the Rotax & Hirth is that with the same reduction ratio they spin the same prop, with better performance from the 582 - but since the Hirth has 625cc - it should really be compared to the 618 Rotax which surpasses the Hirth in both power and torque - ( but is a little pricey)

Mr. Chuck Scrivner
Hirth is air cooled (like most aircraft engines)

A:However most cars, motorcycles, snowmobiles, seadoos/ hovercraft/motorcycles/boats are liquid cooled, so what's your point - if you want to fly on dated technology that's fine - but if you look at the accident data aircraft engines have their problems to.

Mr. Chuck Scrivner
Add another $600 ++ for radiators and gauges with Rotax.
And, you get to try to mount them someplace out in the air causing considerable drag.

A:While the Rotax rads might be expensive, most manufacturers are using other systems, on my L'il Buzzard the rad system is just over $100 Canadian. You run temperature gauges on a liquid cooled engine just like you do on an air-cooled.

The only difference is that instead of a CHT you have a water temp gauge. So what's the point? Drag - in most cases you have an engine mounted above the wing, with a massive exhaust and gear drive, and sometimes parachute, big tires, large round struts etc. etc. etc.

These planes we fly don't travel at 200 mph and a little extra drag is just like adding the extra weight of an electric start.

Mr. Chuck Scrivner
Hirth has made Aircraft engines since 1931 and they in fact supplied the Luftwaffe.

A:What's the point - Rotax has been building engines since 1908 and currently supplies 80% of the worlds ultralight aircraft engines.

Mr. Chuck Scrivner
Hirth doesn't offer 3 day mechanic courses to any Yahoo that decides he wants to be a "certified Rotax repair station"

A: Since I have been to these courses in Austria for a week at a time, British Columbia, and Quebec I take offense to the "any Yahoo comment," - people that have attended these courses with me include Lockwood Aviation, LEAF, CPS, Greensky, South Mississippi Ultralights, Reg's Small Engines, and many others - all are involved in the industry.

The cost of these trips to this "Yahoo course" run between $2,000 and $3,000 per person. These course keep us updated on changes, and many of the improvements in the Rotax engine line have come about because of us. The dual ignition, stronger crankshafts, gear drives, exhaust systems all came about because of our industry input.

Mr. Chuck Scrivner
To do more in these aircraft application engines is not recommended (referring to engine rebuild parts). Rotax sells the parts to do it...because they are supplying for snow mobiles and jet skis.

A: Rotax AIRCRAFT engines are TOTALLY different than those used in snowmobiles and jet skis. The ignition is different, the cylinders are different, the exhaust is different, the carbs are different, the crankshafts are different, the crankcases are different, and the cylinder heads are different, so your wisdom here just got flushed down a toilet.

Mr. Chuck Scrivner
The web site (www.ultralightnews.com)  is big so I may have missed the area that contained all of the Hirth info as stated by Mr. Loveman.  I would very much like to be directed to that area so that I may glean as much info on my engines as possible. One can never know enough.

A: No but some can have a little and make it sound like a lot! To my knowledge I never stated there was information on the Hirth engines on my site. I have over 1500 alerts to date of which over 100 deal with Hirth engines. When I get back from Sun N Fun I will try to get some time to do troubleshooting reports on the Hirth line - just like I did on Rotax - but then I will probably get a nasty letter from Hirth or a Hirth dealer telling me that they "have never heard of the problem."

Mr. Chuck Scrivner
Aircraft Spruce and Specialty, the leading aircraft parts supplier in the USA sells and services Hirth.   Ph. 1-800-824-1930. They are located on both coasts. (That's all that really needs be said about distribution) ...but there's more....
Recreational Power Engineering 1-800 583-3306 For Best service and info in Ohio.
East Side Engines in Washington at 1-888-9161.
Hirth has only just begun it's North American Distribution system. It is definitely growing!


A: Aircraft Spruce, is one of the best companies in this business - as are all of the Rotax Service Centers around the world. The advise - I gave was that if you are looking for service look right now to Rotax because they have been there since day one, you can get parts and service world wide. I am not knocking Aircraft Spruce or anyone else - I am simply stating that if you have a problem that you have more outlets for sales and service.

Mr. Chuck Scrivner
So, Mr. Loveman, what SPECIFIC problems have been associated with Hirth that Rotax has never had or does not have or has had?

A:Again what is the point? In three Troubleshooting reports I do nothing but name the problems with Rotax engines. Why, so that I can sell parts to someone in the U.S. or other parts of the world. Or so that I can sell more parts to someone on the west coast of Canada where there is already a local supplier, or in one of the provinces which have their own local service centers. It hasn't happened since my site has been on the web and is not likely to happen, ulpilots support their local dealer-because without him they are in most cases lost when it comes to troubleshooting or shopping for parts.

Mr. Chuck Scrivner
I don't sell or repair either engine therefore I am not economically biased

A: Mr. Scriver I have worked 12 to 15 hours a day for over 20 years in this industry, and if there is one thing I know it is that there is NO MONEY in it. I make a decent living and I am my own boss. I made more money as a General Manager of one of the largest firms in the world 20 years ago than I do now. But I am happy doing what I do. Taking this flack from you is no different than the flack I take from Rotax or Challenger or the other companies that I publish material on that shows the negative side of the coin.

Am I biased towards these aircraft, services, manufactures, or engines? I publish information that is first hand - information that in most cases won't come from a manufacturer or dealer.

Do you as a pilot flying a plane with a possible problem want that information on not?  I only wish someone could have told me of the problems I was about to encounter - before I encountered them. Mr. Chuck Scrivner, you prove to me that there is a better mousetrap out there and I'll be the first to buy it - but prove it with time and experience, not heresay,  gossip, or a personal opinion based on a couple of hours of flying.

U.B. Judge

The following was sent in by a Hirth owner who has read this report:

I just got done reading your Hirth vs Rotax article.  I think I should share our experience with Hirth.  My father (retired UAL and Veteran marine corps helicopter pilot) bought a used Challenger II on floats about two years ago.  It was purchased from a dealer "Charlie Grey" in Seattle.  This particular aircraft won an Osh Cosh award the year it was completed.  It had 300 hours on engine when he purchased it.  3 months after he first flew the plane the propeller broke in half.  One half was still attached to the reduction drive assy. this caused such severe vibration that a lot of hardware de coupled from the aircraft.  (instrument panel, magnetos, etc.) after a non eventful landing in a nearby farmers field we took the plane home and started the repair process.  about a month later we were showing the plane at the Watsonville fly in.  Since then we have an additional 175 hours on plane with no engine related problems.  We have had to replace one of the cylinder heads because of a stripped spark plug thread. (yes this problem appears not to be from over torquing as much as from electrolysis due to over heating.) The only other noticeable irritation from the Hearth is it is real cold blooded when starting.  Anyway I was surprised from our experience to see all the poor associations towards this engine.  Hope we continue to have reliable sound performance from our engine because it is sure fun to fly and a long way to the ground. Regards Chris McDowell 

deckard wrote: I only know of two Hirths, one on a Challenger ll that is local. The owner swears by it. Its the 65hp model. The other is Chuck S. on his personal Hawk. He hasn't posted much about it, maybe he can give some first hand knowledge. Jerry Deckard SEMO Air Sports LLC http://www.sheltonlink.com/~deckard

Hi Jerry Here's my 2 cents worth.

When I first got a Hirth from the Canadian guys the Service was lousy and the engine needed a lot of refinement.The Hirth Distributer in Canada who supplied the the engines for North America went bankrupt about 2 years ago.They had over $20,000 of my money for 4 engines I paid for in full, I thought I lost the money. It took a while for Matt Dundar to legally get to be the North America distributer.Between Matt and the Germans (Hirth) I got my engines even tho the Canadians had my money and kept it. That's pretty good service in my book ,they had no legal obligation to do so.

Now for the engine.I have flown the 2702,maybe a lot of you saw it at Sun n Fun and Oshkosh ,a green and blacked striped Classic and I have a 2706 in my personal plane and love it.I have owned Rotexs too and still sell them and have no problem doing so they are a fine engine as well. The Hirth that is being sold today is not the same Hirth that was sold 3 years ago.

Since Matt Dundar took over he instructed the factory which changes needed to be made to improve the engine and these refinements were added.My engine is different from the first one I sold 3 years ago. As long as a company sticks by me I'll give them a chance to succeed or fail,so far Hirth is succeeding.I wouldn't trust my personal plane to an engine I thought would let me down.Matts orders have doubled in the last year and because of this they were able to contain the prices.

It's a simple fact of business life You reduce prices to induce sales or you can reduce prices because of increased volume and economy of scale.If this brings you to the price level of the competition it's even better.If I doubled production you can bet I'd reduce the price of my kits. It's Business 101... :) Hirth has never let me down since Matt took over, in prices ,parts or delivery so I honestly can't bitch.

This is my experience. Just as 2SI is not the same Cuyuna that I bought in 82 and had problems with ,the same with Hirth. We're installing our first 2SI 70 hp engine in a 2 seat and maybe we'll offer them as well if it works out.If the Hirth doesn't work out you can bet I'll drop it like a hot potato....But I'm willing to not judge the new guy for the sins of the old guys...
My .02 worth Chuck S
Visit our Web site: Http://www.cgsaviation.com

Okay... I don't want to start a war here... I just want to hear some folks experiences with Rotax and Hirth engines. :-) I'm building a Challenger II, and am considering the possibility of going with a Hirth 2706 rather than the standard Rotax 503DC.

I would like to hear from both Rotax 503 owners and Hirth 2706 owners.

* Have you had problems, and what kind?
* Have you had a great running engine that has lasted forever?
* What kind of support have you had if there were problems?
* Has the engine lived up to your expectations?

Please... I don't mean to be overly nit-picky, but I will completely disregard any posts from anybody who hasn't actually flown one of the two engines... I've already seen plenty of opinions that started with, "my brother's best friend's cousin knew this guy who was going with this girl who used to rent a house from a man who had a Rotax/Hirth, and nearly got killed because it quit on takeoff... yeah man... I think it was the flagellator valve or something..." :-)

So please... no opinions, only first hand experience. Thanks!!

Andrew Mueller

Re: Rotax vs Hirth   

Well, I'll make your day. I have been around uls since before they were called uls. I have seen and flown lots of different engines, starting with a Mac 101 cart engine and a new blue head this sunday.

I attended OshKosh and SnF for many years, lots of flyins, etc, I have rebuilt literally hundreds of rotax engines, some of them the same engine for thousands of hours, flown them as a newbie for hundreds and thousands more as an instructor. I've sold six brand new ones since the first of this year, and sure I've seen the 503 come in with a broken crank, seixed pistons, points stuck with no spark, carboned up so bad I could not get the rings out of the grooves with out a chisel. I flew a 503 with a broken crank three miles back to the field, didn't know it at the time though, and I intend to spend many more hours in front of or under a rotax pushing me and my friends through the sky, and the point of all this,

I can't honestly say I have ever seen a Hirth engine fly anything, ever, in all that time, and places and years,,,,,,,,,,,,,,

guess I can't help with the Hirth side,,,,,,,,,

Mark Smith mailto:trikite@evansville.net
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620

Re: Rotax vs Hirth

In article <3961C8F1.1AFD@trikite.com>, Mark Smith <mark@trikite.com> wrote:

A Charming and Enlightening Discourse, Mark! What about the relatively new water-cooled 2si engines?
Brian FitzGerald
Wichita, KS.
"The Air Capitol of the World"

Re: Rotax vs Hirth

Hi Andrew,

Why are you looking at the 503 instead of the 582 which gives the same HP....as the Hirth 2706.

My friend here in Austalia is building a Challenger clip wing special 11 and bought a Hirth 2706 motor 4 years ago when he started to have his Challenger built. The new Hirth 2706 is now upgraded and his Challenger is nearly finished ..yes I would say he holds the Worlds record of 'takng the longest time to build an U/L'

Now...he is in a quandary of what to do with the outdated new Hirth motor.

He and I both , had a 582 Rotax for 3 years until last year on a Pegasus quantum and a Quasar Trike and after nearly 300 hours on each it never once had a hiccup.

The new 'blue top' Rotax 582 is even better and if you are looking for more power like the Hirth 2706 for STOL etc I would not look any further.

My two cents worth.

Cheers Peter
Re: Rotax vs Hirth

  "Dante804" <Dante804@inlink.com> wrote:

My experience is with the 503, although it's not as extensive as others on the NG. I'll give my experience first and then my, er, analysis, ;), below.

I've owned and operated 2 503's, the first was a very early serial no. non-provision points 503 that was on my plane before I rebuilt the plane last summer. It had 25 hours on it since a major overhaul when I bought it; the previous owners had let it sit in the hangar for a year or two with very little running until I got hold of it. I put 70 hours on it with absolutely no maintenance other than replacing the plugs. It always ran perfectly and I never had any problems with it.

Still, I replaced it with a factory new DCDI 503 last summer during the rebuild of my plane. This motor now has about 91 hours on it, again the only maintenance needed having been changing the plugs every 15 hours or so (it's in an inverted installation). I've never had any problems with it; in fact, even the fan belt has not required retensioning in all that time. It's still tight like it was when I pulled the motor out of the crate ;).

But here's the main thing you want to consider when making the choice of which engine to use, and, I might add, the deciding factor for my going with the Rotax over the Hirth: Long-term, in-the-field testing data is simply not available for the Hirth, at least not to nearly the extent it's available for the Rotax. Most of us don't even know anyone who owns and flies a Hirth (although I do now, a friend has a Kolb mark III with a 2706 on it). The Rotax, however, has had nearly as much field-testing, troubleshooting and revision as even some certificated designs! The 503, in particular, has had numerous revisions and upgrades based on years and years of in-the-field experience.

This simply cannot be said of the Hirths at this time. This isn't to say that they're not good motors or that they might be very reliable. I've seen the 2706, it looks like a fine quality engine and the one my friend has appears to run very well. But there simply does not exist the wealth of operational experience with these motors that exists for the Rotax.

This is the primary reason I've stuck with the Rotax. Secondary considerations against the Hirth are the nickle-plated cylinder liners (I would never, ever knowingly run a nickle-plated cylinder liner in a dangerous machine like an airplane), ridiculously high CHT recommendations (400 to 500 degrees!) and the dishonest, silly TBO (1000 hours or something like that) indicating that no one is really sure of a bullet-proof TBO (or even CHT) for these motors. We might know all this for sure in future, but we really don't know right now.

Hopefully, my friend will eventually get his Mark III flying, at which time we might actually get some experience with the 2706....

Lucien S.
Captain America IV.
Re: Rotax vs Hirth

The Prairie Prince wrote:
A Charming and Enlightening Discourse, Mark! What about the relatively new water-cooled 2si engines?
Brian FitzGerald
Wichita, KS.
"The Air Capitol of the World"

Thanks, I like to put things in proper perspective once in awhile...

The air cooled 2si has sufferred from basic design flaws since day one. The axial flow always favors the fan cylinder in cooling, the fan is way too small for exteneded running above 5400, and the materials of construction seem to have degraded since 2si started making the engines.

They have no clue as to jetting for the alternate Bing carb either.

The water cooled 2si based on the 430 air cooled seems to have potential but I was told several years ago by factory people it had no water pump as it was a ski engine only.

This engine with a pump would solve ALL the problems of the original 430 aka ULII02, etc except the recent materials and supplier problems.

The larger 670 3 cylinder sounds like trouble based on several local experoences.

Mark Smith mailto:trikite@evansville.net
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620

Re: Rotax vs Hirth

  Consider this. When you're flying, why would you not want to be using the engine with the longest and best track record. Don't even consider the Hirth. Get a Rotax. The 503 is the best ultralight engine you can buy at any price.

I have hundreds of hours of first hand experience with Rotax engines. I have a small amount of experience with a 2706 because it broke. The 2706 hp is over rated 65, should be 50. Nikisil cylinders are a bad idea, don't believe the hype about expantion rates. And the TBO, has anyone seen a Hirth engine make the supposed 1000 TBO?

Personally I run a 582 but would be running a 503 if I could get by with less power.


Re: Rotax vs Hirth

Hi Peter -
The largest reason that I am looking at the Hirth rather than the 582 is plumbing. I just would rather not have to deal with it. The second reason is weight. There are some good arguments for the 582, (and for sticking with the 503 for that matter), but I am reasonably familiar those arguments.

In the end I may just go with a Rotax, but I want to shop around and do some homework before the decision making process. I am not reasonably familiar with the Hirth, so I'm just trying to gather some objective information to use in comparison.


Pete <pmiller@joynet.com.au> wrote in message news:3961DC31.4342@joynet.com.au...
Hi Andrew,
Why are you looking at the 503 instead of the 582 which gives the same HP....as the Hirth 2706. My two cents worth.
Re: Rotax vs Hirth

Well, I'm definitely not an expert, but I fly two planes, both with Rotax 503s - A Sprint II and a GT400 - one is inverted, one right-side up. I've flown the Sprint approximately 150 hours, and the GT about 20 hours. I've never had any problems at all with the engines. Both of them fly great!


Russ & Martha Oppenheim

Re: Rotax vs Hirth

Thanks to everybody for their input. I truly appreciate it. I'm going to try and compile some hard data on engine problems from both manufacturers and put it all together in a comparison document along with the experiences that I am hearing.
I will post to the list when it is finished and anybody is welcome to a copy of what I have found.

Thanks again!

Re: Rotax vs Hirth 

Dante804 wrote:
Thanks to everybody for their input. I truly appreciate it. I'm going to try and compile some hard data on engine problems from both manufacturers and put it all together in a comparison document along with the experiences that I am hearing.
I will post to the list when it is finished and anybody is welcome to a copy of what I have found.

Hey Dante, I am curious about your responses. Did you get enough info from Hirth flyers to come to any kind of conclusion?

Rick P.  
Daniel Grunloh (in response to Mark Smith)
Re: Rotax vs Hirth

  In article <3961C8F1.1AFD@trikite.com>, Mark Smith <mark@trikite.com> wrote:

Well, I'll make your day. I have been around uls since before they were called uls. I have seen and flown lots of different engines, starting with a Mac 101 cart engine and a new blue head this sunday. I attended OshKosh and SnF for many years, lots of flyins, etc, I have rebuilt literally hundreds of rotax engines, some of them the same  I can't honestly say I have ever seen a Hirth engine fly anything, ever, in all that time, and places and years,,,,,,,,,,,,,,

Mark hasn't actually been to Osh or SNF for some time. I also prefer the Rotax for it's proven record, but Hirth deserves fair mention.

Chuck Slusarczyk, Mike Harmening (and others) have been flying Hirths every day at those shows for several years at least. Contact those gentleman if you need experienced advice on Hirth engines. Matt Dandar, Hirth distributor, will give a seminar on Hirth engines at the seminar tent next to the ultralight barn on Friday 10:00AM.

Daniel Grunloh (grunloh@uiuc.edu)

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