More power than a 582

[herman pahls 9]

I wish this 670 issue could be resolved once and for all with a bunch of very recent success story's in Avids and Fox's.

Rotax Rick claims they as reliable and simple to operate as a 582 and have less fuel burn than a 582 at cruise.

I have been waiting to hear about AK Bob's 670 in a Kitfox.

Any idea how Bob's project is coming along?

If I had a spare donor 582 to send to Rotax Rick I might be tempted to try one.

 

Leni: thanks for alerting me about the "service" bulletin issues with the 912's.

You can almost buy a Pacer for the price of a new 912S and add bushwheels you will have a very capable backcountry airplane.

My son just sold a 160HP Pacer with 31" ABW, Borer prop and a long list of mods. .

Problem was that it only cruised at 100 mph burning 9 gal/hour and needs a full sized hanger.

Is it reality for a Model 4 Kitfox (without the under cambered wing) to cruise at 100mph with a 912/912s burning 5 gph on 29" ABW?

 

Thanks Herman

[Av8r3400 1179]

A good used 80 hp 912 can be had all day long for $5k. You just have to look around and talk to people. The SB issue is the major weapon the Rotax haters use, and its all they have. I personally know early 912 motors that have never had any internal work done, running fine with 2000 plus hours. Maintenance is key. Some day when I have an hour to type ill go through this issue and explain where the SBs came from and why. For the record, the extreme dollar SBs are only for a very narrow band of serial numbered motors.

My plane will cruise in smooth air at 115 mph, burning 3.5 gph, on 21" tires with only 80 hp. I would say a 100 hp motor would have no trouble hitting your speed goal, maybe an 80 too.

[akflyer 1427]

Larry,

 

I am not a Rotax hater.. but I did just get a service builletin from rotax yesterday as I was typing that   Yes it affects only some engines, my point was, if your getting a used one, MAKE SURE that it does not happen to affect the engine YOU are about to buy.

 

Herman, I am with Larry, I think the KF IV will do what your asking, it just wont get in and out quite as short as your II, but it is DARN close!

 

[Av8r3400 1179]

Leni, I didn't mean to imply you are.  But there are many people who do use the overdocumentation by Rotax as a reason to hate them...

 

Two years ago at Airventure, Rotax celebrated selling their 40,000th 912 motor.  They couldn't have gotten that far in 20 (?) years, far eclipsing most "certificated" motors, without it being a good (great) product.

 

 

 

The short SB story is:  The US Government uses 914 motors in some drones.  These planes fly at full power for 30+ hours at a crack straight, at 30+ thousand feet of altitude, in the far corners of the world, being maintained by soldiers in the field.  Far exceeding the abuse that any "normal" person would subject a motor to.  Every time any one these motors fart or hiccup in the least little bit, a service bulletin is written.  Most of this does not even come close to applying to us in the "real" world.  Because 900 series motors share parts and design, the SBs technically would apply, but practically do not.

[Mendlerr 4]

A good used 80 hp 912 can be had all day long for $5k. You just have to look around and talk to people.

My plane will cruise in smooth air at 115 mph, burning 3.5 gph, on 21" tires with only 80 hp. I would say a 100 hp motor would have no trouble hitting your speed goal, maybe an 80 too.

Well I'm sold, who do I make the check out too?  I wish I could find a 912 for only $5k in good shape.  I see some used 2-strokes selling for that price.

 

If anyone see's one of these please let me know, I've been searching and just cannot find one at these prices

Edited 5 Jun 2013 by RMendler

[Av8r3400 1179]

1. Join your local EAA chapter

2. Talk to everyone there

3. Ask questions and listen to everything not being said

4. Find the guys upgrading or talking about upgrading to a 912S or 912iS

5. Find out who is old and or dieing, seriously.

One of my chapter mates just bought a new in the box 1998 model 912 UL 80 hp motor for $6500. He bought it out of state (he wont say where) off a widow selling off the "junk" in the garage.

They are around.

Edited 5 Jun 2013 by Av8r3400

[Mendlerr 4]

Sounds good, I'll do that.  I told a guy flying a KingAir 350 that my airplane had a 2-stroke 64HP engine.  His eyes got huge and he said I had a death wish.  It was kind of funny.  Here in NC 2-strokes are looked down on pretty heavy, I haven't made too many friends and no one will fly with me.

 

A 4 stroke would be nice

[BryceKat 125]

I told a guy flying a KingAir 350 that my airplane had a 2-stroke 64HP engine. His eyes got huge and he said I had a death wish. It was kind of funny

That always cracks me up! I know more guys that have had an engine failure in a "reliable" Lycoming Continental 4 stroke than have in a 2 stroke. Bryce

[6320012s 12]

The way I look at it , 2 strokes filter out bad company!

[herman pahls 9]

I have appreciated all the responses to my "more power than a 582"

Since there does not seem to be any low cost readily available options right now to replace the 582, I will answer my own question.

This answer is not very profound.

Get rid of the FAT.

My model 2 preformed the best 18 years ago when it first flew with a 532, A gear box, with snow mobile single ignition and weighed 465 pounds.

In 450 hours the 532 never let me down.

Every thing I have done since has added a lot of weight but features I do not want to do without.

I was told by others that for reliability I should get a 582 with dual ignition and at least a B gearbox, so to make myself feel better, I had the 532 rebuilt at 300 hours and the A box every 100 hours.

I guess that the 582 and C box added at least 15 pounds and my Kitfox model 2 did not fly as well with that added nose weight.

Plus the 582 did not idle as smoothly or as low in RPM as the 532 because apparently the 582 ignition does not retard the timing at idle like the snowmobile ignition does.

I cannot stand gearbox chatter or too much idle thrust when landing so I installed an RK clutch and love it. Add another 4 pounds up front.

Then I added inflight adjustable to my IVO and another few pounds way up front.

This added weight up front is raising my stall speed and diminishing the handling qualities.

The HACman does not add much weight but I would not want to fly without it especially with the polyswitch idea that came from the "bare footer" on this forum.

I want to land where my son does in his Maule so I installed 29" Airstreaks which add 33 pounds over the 21" ATV tires.

The forward CG is still within limits but it flys poorly and lands even worse especially power off.

I install a taller and wider Matco tailwheel which adds 3 pounds and an additional 12 more pounds of lead to the tail and it now flys and lands great.

The taller tailwheel reduces the A.O.A. by a few inches which is counter productive for STOL but works well in soft sand.

The only reason for Bushwheels is for landing on larger rocks or softer sand which requires very low air pressure to absorb the rock hits.

My Kitfox is noticeably much harder to push around due to the low air pressure and now requires at least 300 feet to levitate at sea level with no wind.

Conclusion; I really do not need "more power than a 582", I need to go back to 21" tires with plenty of air pressure to reduce rolling resistance, go back to the hard rubber Maule tailwheel and get rid of the 12 pounds of lead in the tail.

I will not give up the RK clutch, IFA prop or HACman.

(Big tires also require bigger and heavier brakes which I do not want to give up even with the 21" tires).

By getting rid of the FAT, I will get some useful load back and at least be able to take my wife with a few gallons of gas.

"Big rocks and long props" is all the rage these days in backcountry flying but it comes at a price and sometimes a very steep price due to bent airplanes.

I vividly remember 25 some years ago when Dan Denny landed his Demo Kitfox sideways on the same 4000' runway I fly off today.

These Avid's and Fox's do best when you keep them simple and light.

Now that I have confessed everything I have done wrong to my Kitfox, I do not want to turn back and still want more power.

I am hoping that Leni has immediate and great results with his new engine or I find a 912s in a barn.

Thanks for listening to me talk to myself.

Herman

[Av8r3400 1179]

I've never met you so I don't know, but is there maybe 10+ pounds available for the pic to loose rather than equipment off the plane?

That's currently the project I'm working on...

[Mendlerr 4]

The way I look at it , 2 strokes filter out bad company!

I like it, lol.

And to the last post. I think if I lost 10 to 15lbs my plane would feel quite different in the air. I'm looking to upgrade to 21" tires, so weight is a concern since my Kitfox already weighs a bit much. 628 empty

[Av8r_Sed 82]

Good post, Herman.  Tough decisions, but I think you hit the limit on that airframe. 

 

Like others posting, I decided the most useless weight in my plane was my extra poundage.  It's not the easiest or quickest route to improving performance, but is probably the most satisfying overall.  Of course you need to have a surplus to start with.

[akflyer 1427]

In my case, I could stand to loose about 40 more pounds of dead weight, and not off the airframe... You are absolutely right on the plane itself though, lighter is better.  It seems over the years e have taken these things from a GREAT performing low and slow, bare bones back to the basics stick and rudder plane, to trying to make them a cross country plane with more speed, more yada yada yada... The original A model Avid with a 340 Cayuna wold kick the crap out of my plane in terms of STOL..  But like you, there are some things I am just not willing to give up!  Randy has the 26" airstreaks on his and I think you would be happier with those than with the 29s.. you can run them around 5-8 pounds and they will still soak up the bumps and rocks and not give you the rolling resistance that you have now.  You have to let your out to probly 2 or 3 PSI due to the thicker side walls and general construction of the tires on the 29s.  Sell the 29s to someone with a Tcrate and try the 26s before you totaly decide to go back to the 21"

 

[LORENZ 9]

Did you end up with a 670 Herman?

[Av8r3400 1179]

He wound up buying a 100hp 912 powered Kitfox IV.