HKS four stroke opinions? Experience?

[GeorgeHedinger]

I saw a reference to the HKS four stroke engines on
another web site. Does anyone know anything about
these engines?
Anyone actually used one and can report on
their reliability or UNreliability?
I've never seen them mentioned here on this forum.

[GyroRon]

they are very nice and dependable engines. Only thing to keep in mind with them is forget the rated horsepower and consider the power output to be just slightly higher than the power you get from a Rotax 503 DCDI.

[GeorgeHedinger]

Thanks Ron,
I'm guessing that the HKS would probably cost about twice as
much as the Rotax, right?
It's just that I have a long standing distrust of two stroke engines.
I've never owned anything with a two stroke that was reliable enough
that I'd trust my butt with it at 3000 feet. LOL!
That includes ESPECIALLY the Kawasaki on my ultralight that seized up
twice on me on climbout from Sussex airport years ago.
Made for some interesting moments.

[GeorgeHedinger]

Thanks for the input Steve.
I took notice of the HKS because it is similar in design to a BMW motorcycle
engine, something I have a LOT of experience with.
My 1974 BMW has 172,000 miles on it and the engine is ALL original.
That means that at an average of 50 mph, my engine has well over
3,000 hours on it with NO failures.
Now I am seeing ads in the magazines for kits to convert
BMW motorcycle engines for light aircraft use.
Considering my experience, it looks like a VERY appealing choice!
But I'd like to talk to someone who's actually DONE it first.
I believe the Verner engine is also similar, but Ken Rehler
did NOT have good luck with that one!
So, a similar design does not neccessarily mean similar reliability, eh?

[rfonseca]

I had one of the first HKS in a Ultralight. Power is a little more than a 503 and much less than a 582. Had crackings in my muffler because of strong vibration of this engine. Changed it to a 582.
I understand that the new HKS have solved the vibration problem.

[rfonseca]

Also, GPH were minimum. Less that 4 gph.

[GyroRon]

It is only money right??? If money is no object go HKS. It burns less fuel and should give a LONGER service life. Don't know if I would say it is more reliable. It is a SMALL engine that has to rev high rpms to make power, IOW's a lot of small fast moving parts that can fail.

A 503 OTOH, has only a handful of moving parts. the crankshaft, two rods and two pistons. Both engines have a gearbox or means of prop speed reduction. The 503 is very dependable. And very SIMPLE. I think it is easier to get better service out of something very simple than something somewhat complicated.

I know several people that have 500-800 even a few with over 1000 hours on their 503 Rotaxs with out ever doing anything but adding gas and flying. Rotax reccommends a lot more maintance and more often than anything else, but the price savings allows for the work you will do over the years.

My vote is for the 503.

[cgmg]

I agree with Ron regarding the 503. They are fairly easy to work with, no radiator or other systems to fool with. And pretty much everyone around is familiar with them, as they are good starter engines for newbies, or people without a lot of dough to throw into bigger engines.

[GyroRon]

Rotax puts a 300 hour life on their two stroke products to protect their backside so to speak. If they extended it to 500 or even 1000 hours as Hirth does you would see more failures and Rotax would quickly earn a bad reputation... Bad Rep = Bad sales.

In a Rotax 503 there is very little to go wrong with the engine to cause problems. There is a belt driven fan that needs to be used for pusher applications that if broke would overheat the engine, Then there is the carbs that if gone out of mixture adjustment could lean out the engine and cause seizure or richen up and cause a plug to foul. But if the temps are kept in check and the mixture is right a Rotax 503 will be a trusty as anything out there.

My advise to anyone who cares, is to follow the Rotax maintance schedule and take care of the engine. If you do so you can pretty well count on good dependable service.

A two stroke engine isn't a bad engine design, it is just more important with a two stroke to have the engine in " tune "

[GyroRon]

Cool take some pics Steven. I got a good crowd around Rusty Nances computer over at the Dominator camp one night down at Bensen Days and played the sportcopter loop video you sent me. Made for interesting disscussion afterwards.

[GyroRon]

Send them.

[GeorgeHedinger]

Thanks for all the input, guys. That's what I like about this forum. Lot's of good
info and differing opinions to think about.

[Sonnyj]

HiYa Ron Spent the last couple o days drulin on my screen,[IE lurkin]thank you and all the other people for the wonderfull work onletting us noshows see what we missed.Maybe next year I'll be more prepared to make the trip.I would like to getup with you one weekend soon so if you get a window let me know.Right now I'm in the middle of an out of frame overhaul on a 60 searies detroit so I'l be on that for the next 5or6 days.Thanx again for the pics Sonny

[GyroRon]

I will be at the airport this Sunday all day. The airport is in Indian Trail North Carolina.

[Sonnyj]

Hey Ron Please give me a rain check,I gotta have the Pete runnin monday night.Thanx Sonny

[Greg Mitchell]

Gyro Ron,

Ron I am thinking about going to the 582 rotax on my Butterfly, had intended to test out the 503 initially. I have my weight down to 83kg (183lbs). Fully kitted up for cold climate flying expect to be around 90-92kg (198-203lbs). So all up weight should be around the 500lbs. 503DCDI still a good option for me to solo? Thanks.

Regards,

Mitch.

[GyroRon]

I haven't flown a Butterfly so it may do better or worse than I would expect with a 503. The gyrobee I have been flying for example has been hauling me around pretty good - 215 lbs dressed - with only a 447. So each gyro will be different.

The Dominator Ultrawhite I flew at Bensen Days and over the news years fly in, did pretty good with my weight and the 503. But..... It flew slower over all and I had to run the engine harder over all than if it had been powered by a 582.

In all of the 582 powered dominators I have flown - quite a few - once I have climbed out I can throttle back to the mid 5000 range and cruise at 60 mph easy. The 503 powered gyro took closer to 6000 even to cruise at 55 mph. Top speed on the 582 models was close to 100 mph where as the 503 model flat out would only get to about 75. Now the 503 model was the only one without a pod and windshield. I believe that the 503 would perform better in speed range and cruise Rpm needed if it too had a pod, But It would suffer in climb.

So long story shorter.... I would say it is up to you. 503= less money, much simpler, burns less fuel, and I would say more dependable too, but you will have to run it hard to get reasonable performance. 582= more money, more things to fail, more fuel, less dependable, but much more performance....

[Greg Mitchell]

Cheers Ron,
I reckon I'll stay with the 503. I am about to solo and my instructor keeps suggesting I look to the 582 for the extra Grunt, I am tempted. Do any of you guys think there is any reason to think soloing a 582 as against a 503 is a safer way to go, ie reserve of power, ect? Thanks again for the detail Ron. Appreciated.
Mitch.

[Greg Mitchell]

Gentlemen,
Can I put my question another way. If my all up weight is say, 510 lbs and my average thrust produced is around 275 with a two blade Tennessee prop, off of a 503 DCDI, then is there really any argument from a safety point of view for stepping up to a 582? I understand it's always nice to have a little extra in reserve, I also understand that the 503 will be working harder for longer and for less money but if we have more than the half the weight in thrust, then 503 at these figures would be within the safety margins?

Regards,

Mitch.

[GyroRon]

As long as the trust is half or more of the all up weight it will fly safely. On a hot day it might be marginal at this ratio but it should still fly. You are a little better with your 503 so I think you will do fine.

[Greg Mitchell]

Thanks Ron.

[weka]

Is a Rotax 503 a good option for a learner pilot ? What sort of maintainence do They require? and how long do they usually last before a rebuild is required?

[MattPearson]

Hey Greg and Ron,
I occassionally fly a 503 Air Command with 23 ft DW's and it flies me great.(of course it's no SUPER FLY, but hey...) I wiegh 200 in my birthday suit. The Butterfly with a 503 weighs 75 lbs less than the Air Command, so that should give you an idea of performance. With the 582 , "G-force landing gear," prerotator, after muffler, intake silencer and battery, the Butterfly, or Monarch weighs 360 empty.

[Greg Mitchell]

Thanks Matt,
Can you have a look at my post on the Dragonwings thread. Our Oz Blades may be a tad heavy still, not sure exactly how much this will upset the balances, waiting to hear back from Larry. Nice family pics Matt. :)
Mitch.