hirth versus rotax

Published by: monty stone on 10th Aug 2017 | View all blogs by monty stone

queen victoria was 'gone' so it had to be in the present century i convinced my wife we HAD to go to sun n fun florida, no mean jaunt from seattle, like driving from scotland to bumfuk, egypt. on a powered parachute stand they had 65 hp hirths for $3000. fuel injection, electric start, pru 1 yr warranty and 1000 hr tbo! thus began several years of misery, and 3 emergency landings. i performed the run-in EXACTLY per the mfrs instructions . the first problem was early on, the engine wouldn't rev past 3500. it was only after me sucking and blowing in the vent line on the f.i. control unit the rpms shot up to7000! the unit was programmed too rich. the first engine out was at about 12 hrs, inc 10 hrs ground run, as per the hirth instr. i was able to land out on camano island wa and tlr it home. the mag side inner main brg had locked. up due to the ball cage having been spot welded together, instead of a delrin cage. hirth īrefused any warranty help, and i was busy grabbing all the used parts i could  find, i would be needing them! i did ship my crank to germany for possible warranty re-consideration, they 'lost' it. my next engine out with this unit  was around 200hrs when the fan belt shredded, the cyl hd temps skyrocketted and while descending a spark plug, with its lead flew past my head, taking the puny 10 mm thread with it., i had to set it down in snake infested scrub land in az, and stumble through half mile to a road. the next, and last engine out was again the mag side inner brg ball cage having broken up, locking the crank.(different crank and case!) i published tthis misshap on ttps. to sum up, the 1000hr tbo is nothing but a sales dept lie. the design flaws are many and even though 'on paper' it looks lovely, my experience is not a 'lovely' one. the us importer, mat, did everything he could to help, tthough not free! but corporate hirth sucks! i may have skipped over other 'problems with this engine, but unless you enjoy a challenget, 'relax with rotax'.                              freazier ballszoff                                                                                                                                                          ps, having read larrys comment i remember now the crankcase was cast styrofoam, my pru bolts all stripped out, totally unpleasant.pps, is anyone out there still flying with this engine? hello , hello.                                                                                                                                                                                                                                

Comments

21 Comments

  • Larry  Mednick
    by Larry Mednick 5 days ago
    Monty, that last awesome engine out video that was just posted a few weeks ago was a Hirth...
  • monty stone
    by monty stone 5 days ago
    I musta missed it, the good news is it was running long enough to almost reach the 'crash' site, the bad news is...................... there ain't no good news! Except you do learn to glide.
  • Job Chithalan
    by Job Chithalan 5 days ago
    Thanks for sharing your experiences.
    was it a 3203 or the liquid cooled 3503 ?
  • monty stone
    by monty stone 5 days ago
    Job air cooled 2706
  • monty stone
    by monty stone 5 days ago
    If you can view a hirth'coupling made for I believe early porche race cars, which had roller bearings with a 'built up' crankshaft using the ingenious Hirth coupling, it resembles oranges cut in half hollowed out and made to fit with incredible precision . Too bad they 'lost' it.
  • Bradley  Waters
    by Bradley Waters 5 days ago
    I thought it was a MZ 202?
  • monty stone
    by monty stone 5 days ago
    No it is a 2706 air cooled 65 hp,
  • Frank Dempsey
    by Frank Dempsey 5 days ago
    Right. The MZ202 is another failure, in my opinionated opinion. My friend, Roger Hooker had a Butterfly 103 Gyro with the MZ on it. 65 HP is a good thing but In less that 50 hours, it blew a plug out of the socket. Roger put it down safely and he's a ameticulous mechanic. Get a modern 4-stroke if you can afford it.
  • monty stone
    by monty stone 5 days ago
    Yeah frank several promising eastern European four strokes but probably under-funded so they won't make it either, I'm pretty sure rotax rely on 'other' sources of income, other than 'uls'.
  • Abid Farooqui
    by Abid Farooqui 5 days ago
    Actually Rotax is a stand alone profitable division within Bombardier. They have to be profitable on their own without help from the rest of the company. BTW the rest of the company isn't doing too great last year or so. MZ and Hirth suck.
  • PHILIP QUANTRILL
    by PHILIP QUANTRILL 5 days ago
    How about widening the discussion to take in the other engines used on trikes, Suzuki, BMW etc. How do they stand regards initial cost of changeover, power to weight, reliability and general running costs/maintainance ?
  • monty stone
    by monty stone 5 days ago
    Abid I was comparing rotax aero engine div relative to the other engines they sell, m/cycle, orv snow and water craft, industrial, cart,etc
  • monty stone
    by monty stone 5 days ago
    IF (the biggest word in the English language!) only my 2706 had been born with Delran caged brgs, carbs,14mm plugs, 8 mm head studs that went into the crankcase, a la rotax, instead of puny little 6 mm 'screws' , and tiny 10 mm plugs, a 'metal ' crankcase, etc, hirth woulda been a contenda ! Plus fire the S.O.B that came up with a 1000hr tbo, and other lies. The reason for the parachute guys 'offing' these engines at cost was rotax threatened not to sell them engines if they didn't get rid of them. The reason, given, by Hirth for refusing me any warranty consideration, was I bought it from parachute guys, and not their dlr, even though the unit was sealed in the Hirth carton, and they had bought fifty of them from their Hirth dlr.
  • Larry  Mednick
    by Larry Mednick 5 days ago
    The Suzukis, BMW and Yamaha are all working well from what I have seen and heard. The RX1 Yamaha is the badest coolest sounding, most powerful motor you can put on a trike thanks to Teal Jenkins in AZ making the kits. The Suzukis you can get kits from a few places including A turn key now days for about $10-$12K.

    But at the end of the day I feel the Rotax 912 is a cleaner, better, complete assembly for our application with extremely reliable service and enough of them out there to mean you probably won't be the one to discover a new problem that would bring a SD to the attention of the entire fleet.

    It's sad to hear and see the problems we have seen with Hirth and MZ. Normally I encourage market competition and try to never bad mouth any brands, but this is serious and people are getting hurt and killed and ripped off due to inferior, unreliable designs being marketed as equal or better.

    Let's look at the MZ 201. The intake manifold is so large the low pressure creates a puddle of water in the bottom of the intake and while flying it you can hear the water going through the engine. So I had to fill the intake up with JB weld (my fix) and reduce the volume by 50%. Next the head gasket was blowing every 5 hours. This was caused by lugging the motor by propping it to 4800 RPM. The fix was to reduce pitch so it could red line to 6500 and then limit the carb throw to 4800 rpm again. Next the carb did a terrible job of carbureting. So I put a Mikuni on it. Then the belt redrive kept slipping. The only solution is to overtorque the lock bolt. Then the engine was overheating. The solution was to flip the redrive down so more of the mid span of the prop would draw the air away. In the end the engine ran great. Long term I have no idea. But no solutions were given for any of these problems and I took it upon myself to fix this ill motor as I described above. There is a problem when the manufacturer is selling a motor with these issues as if it's a good running motor. COMPLETELY UNACCEPTABLE!
  • monty stone
    by monty stone 5 days ago
    Yeah Larry, the end user of an engine shouldn't have to be a development engineer/test pilot.
  • Larry  Mednick
    by Larry Mednick 5 days ago
    I forgot to mention again the newer Hirth 50 HP horizontally opposed twin is getting very good marks and lots of success on the Explorer 103 trikes. The 80 HP flat 4 cylinder has not had the such luck blowing spark plugs out the head etc.
  • Paul Hamilton
    by Paul Hamilton 4 days ago
    I have only heard bad comments about previous Hirth engines so I try and stay away from them.
  • monty stone
    by monty stone 4 days ago
    larry i rember now, it was a mz 202 .
  • Larry  Mednick
    by Larry Mednick 4 days ago
    You're right Monty. Is it any wonder how I interchangeably confuse the two? All the same to me... we need to do an MZ vs. Hirth forum. Now that would be a good challenge! ;-)
  • monty stone
    by monty stone 4 days ago
    a fly buddy here at arlington bought a new mz202 flew it on his titan for 40 hrs then it puked a piston. no help from the dlr in canada.
  • monty stone
    by monty stone 4 days ago
    in defence of hirth, while it ran it was smoother than rotax idled better and much lower rpms due to the big rubber donut drive coupling and starts very easily on pullstart, has a fatter spark at lower rpms than rotax, also has a wire cable ,not a piece of clothesline. it gave good power, but as stated i was getting too much glideing. in fact, i even redrilled the motor mounts to quick change my 503, while my hirth was 'broken' . i got way too much engine swap time. with a bit of re-design it coulda bin a contenda! . i had to heli-coil the trans mounts and sparkplugs threads , due to poureous casting. the cylinder base gaskets were 1/4inch 'cardboard! many strange design features skinny little flat fan belt!
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