Getting an old kitfox IV speedster up and running!

[Hockeystud87]

tl:dr: I want to get a kitfox that's been sitting for 10 years that is in good condition ready to fly, what is your advice on how to do this?

So I have a question for the Kitfox owners in this group or anyone who knows about Kitfox's. I am currently in the process of getting my tail endorsement in a Cessna 140. Once I get signed off I would like to fly a Kitfox. My grandfather has a Kitfox IV Speedster that was built around 1992 with a 80 HP Rotax 912 carburetor motor, that runs on auto gas. He has over 500 hours of time on the frame it's self and my grandfather is a superb craftsman. It has been in a hanger for it's entire life and my grandparents take extremely good care of everything from their cars to tables and obviously their planes. Here's the question:

The plane has not flown in maybe 10 years, did a run up about 4-5 years ago. I want to get this plane ready to fly to hopefully get to spend more time flying with my now 90+ grandfather by flying my grandfathers aircraft with him, but I want to be safe obviously!

What are some key things I would need too look at? Do the diaphragms in the carb need replacing? Fuel lines? Essentially what would you do to get a plane that's been sitting for a while but still in really good condition ready to fly? Thanks for all the help!

10817

[tommg13780]

It looks like you have a "Speedster" there which is the Kitfox clipped wing version. That's the same version as I fly.

[Hockeystud87]

Yea you're right! I hear good things about them what motor and cruise speeds you get?

[tommg13780]

With the 912/80hp IVO ultralight Grd Adjust prop 110-115 mph at 5500rpm. Average climb solo around 1500@60mph. All speedster mods.

[Hockeystud87]

Dang it sounds like you have pretty much the exact same plane as the one we got. 1500 is crazy climb rates. Whats your opinion on the handling? I have about 100 hours total and maybe 8 in tail draggers. Are they any more difficult than a regular T-Dragger?

[Dusty]

I have been through his a few times myself.
Chech paperwork ad's etc.
If it's rubber and critical to safe operation REPLACE! Including bungees.
Check tank condition and do a flow test.
Don't rush,take your time and be thorough(she's waited 10 years already).
Plenty of ground running wont hurt,then get a LAME to do an inspection.

Well that's the Readers digest version!
I'm sure others will add points I have omitted.
Nice machine by the way:)

[Hockeystud87]

I have been through his a few times myself.
Chech paperwork ad's etc.
If it's rubber and critical to safe operation REPLACE! Including bungees.
Check tank condition and do a flow test.
Don't rush,take your time and be thorough(she's waited 10 years already).
Plenty of ground running wont hurt,then get a LAME to do an inspection.

Well that's the Readers digest version!
I'm sure others will add points I have omitted.
Nice machine by the way:)

Thats good advice, if anything it would be a great time with my grandfather trying to learn his plane. What did you think of the handling of your kitfox?

[av8rps]

That is a great story about wanting to get your Grandfathers Speedster going again, and flying with him. That looks like a great little Kitfox.

I really like how the Speedster flies, it is really a sporty, fun flying airplane. It is a very nice handling tailwheel airplane. If it doesn't feel that way, there is something wrong with the tailwheel set up (which can be a common problem, so again, if it feels difficult and hard to control, it's most likely the tailwheel set up, not you).

For cruise, a nicely set up Speedster with reasonable streamlining efforts should easily get 120+ mph for cruise. I flew the factory glow in the dark green 912ul Speedster with a crappy wood prop on it that was over pitched, and we were seeing nearly 135 mph TAS at 5300 rpm. I think it would have done better with a bit less pitch, as it couldn't even hit 5500 rpm wide open (which means it wasn't developing max HP). My experience with a 912 has shown that you will have the prop set best if you set it up to get about 5600-5700 rpm when wide open straight and level. Obviously your mileage may differ, but generally I think you will find those numbers to be pretty good.

Note; With the prop set as I suggested you will probably get less climb rate than TommG is seeing with his. But based on what he posted, I think he could add some pitch to his prop and actually get higher cruise with just a little less climb. He also is not using wheel pants, so that's also a few MPH less.

[Hockeystud87]

That is a great story about wanting to get your Grandfathers Speedster going again, and flying with him. That looks like a great little Kitfox.

I really like how the Speedster flies, it is really a sporty, fun flying airplane. You should easily get 120+ mph out of one for cruise. I flew the factory glow in the dark green Speedster with a crappy wood prop on it that was over pitched, and we were seeing nearly 135 mph TAS at 5300 rpm. I think it would have done better with a bit less pitch, as it couldn't even hit 5500 rpm wide open. My experience with a 912 has shown that you will have the prop set best if you set it up to get about 5600-5700 rpm when wide open straight and level. Obviously your mileage may differ, but generally I think you will find those numbers to be pretty good.

Note; With the prop set as I suggested you will probably get less climb rate than TommG is seeing with his. But based on what he posted, I think he could add some pitch to his prop and actually get higher cruise with just a little less climb.

Interesting information. I personally think anything over 1000 FPM is more than needed, so I'd prefer a faster cruise my self. We have the adjustable pitch prop for on the ground. So when we get it flying I might play with it and try and get a better cruise. isnt the Vne speed of a kit fox 135? I'm guessing the Speedster has a higher Vne

[av8rps]

The best advice I can give you about making sure the engine and airframe are safe is to befriend an experienced 912 Kitfox guy in your area and ask him to go over the airplane with you. The more eyes, the better.

I also think Dusty's advice was good, especially about replacing rubber parts.

And if you decide to adjust your prop pitch, use an electronic angle finder in the same place on each blade so you know they are all exactly the same.

[Slyfox]

the other day I ran full throttle and high pitch and pulled straight up, over 2200 climb, wooo hooo. lots of fun, what do you mean 1000 is all you need?:D

[DesertFox4]

Welcome aboard Al. Nice looking Kitfox.
I would imagine that the Kitfox has not had a recent Conditional Inspection. That would be a starting point. To see a Kitfox conditional inspection checklist just click on Kitfox Aircraft's ad at the top left side of every page and find the their "Technical FAQ" tab. Click on the 2nd entry.
As discussed, all hoses may need refreshing. I'd drain all old fuel out also. Go through both carbs. Learn all you can about the care and feeding of your 912 engine. They are wonderful little engines.
You will love the flight characteristics of that nicely built Kitfox.

[avidflyer]

Should be a nice airplane. By the way, I sent you a private message. Jim Chuk

[Wheels]

Im excited for you! The story sounds great! I bought a kit fox model IV that had been sitting for about 10 years. The mechanic who sold it to me was a great guy and did his best to make it right before he sold it for his friend.
He was an A&P mechanic so he did a lot of A&P type fixes. That said, The plane needed a Rotax Certified mechanic and a Light Sport Repairman to look at it.

Get those two wickets and you will be golden. Although I bet your grandad knows more about that plane than most lsrms will ever know.
My plane needed the following items.
1 Rubber vibration dampners
2 new carb sockets
3 rebuilt carbs
4 inspection for the notorious crack in the engine mount. (new mount is beefier)
5 new fuel pump to replace the now obsolete pump. (if it aint broke don't fix it)
6 a return line to the tank
7 additional leaf spring on the tailwheel as mine only had one and thats bad.
8 inspection of the fuel tanks revealed the old fuel had eaten them up pretty badly. I installed the ethanol resistant tanks.
I got an A&P who owned a Kitfox to do most of it.
I'm in Clark Fork Idaho. Where are you exactly.

[Jono]

My plane needed the following items.
1 Rubber vibration dampners
2 new carb sockets
3 rebuilt carbs
4 inspection for the notorious crack in the engine mount. (new mount is beefier)
5 new fuel pump to replace the now obsolete pump. (if it aint broke don't fix it)
6 a return line to the tank
7 additional leaf spring on the tailwheel as mine only had one and thats bad.
8 inspection of the fuel tanks revealed the old fuel had eaten them up pretty
Wheels has summed it up pretty well. My dad built the Kitfox IV I fly now and the only thing on this list we haven't done is replace the fuel tanks (we're watching closely.. but will have to do them one day) - Main thing is to avoid ethanol fuel which we have been doing.

Jono

[Hockeystud87]

Hey guys,

Sorry for the late response! You all gave great info.

To update I just got my taildragger endorsement in a beautiful Cessna140 yesterday! Awesome experience getting to learn a new appreciation for ground handling and learning the different effects of Wheel and 3 point landings.

So now the next steps I want to take are trying to really focus on my grandfathers kitfox. Were going to tackle it early next week and he's written out a check list to start going over it's "annual". I also discovered that the plane is actually the 80hp version rotax not 100hp.

Some concerns I have after searching the site here is my size. I am a 6'2" 180lbs guy. I have always been slender but when I sat in the plane last it was "tight", The full controls was somewhat of an issue but I was able to get pretty decent throws with out issue, if I moved my legs around I could get full throw easily but with a slight awkward position with my legs.

I was also thinking of removing my shoes and maybe taking out back padding to help make some room.

I'm excited to work on this plane and have a great slow & cheap plane to build some time in.

Any advice?

[Jesse]

I revived my grandfathers KitFox 5 a year ago after sitting for over 15 years, I had to do all of the same things you guys have talked about. Carbs gummed up a few times before we got all of the crap out of the old tanks. Now i run only 100LL and have no problems with carb junk from the fuel tanks eroding away. I hat to have to do the work required to remove and install a new one. Cheaper for the short run to burn 100LL. Last thing i need to do the the engine mounts... some day soon.

[Dusty]

Don't stress too much over controle throws,full back stick is required but side to side full movement is seldom required as these aircraft have good roll authority even at low speeds:)

[jrevens]

...

Some concerns I have after searching the site here is my size. I am a 6'2" 180lbs guy. I have always been slender but when I sat in the plane last it was "tight", The full controls was somewhat of an issue but I was able to get pretty decent throws with out issue, if I moved my legs around I could get full throw easily but with a slight awkward position with my legs.

I was also thinking of removing my shoes and maybe taking out back padding to help make some room.

I'm excited to work on this plane and have a great slow & cheap plane to build some time in.

Any advice?

I'm about the same size as you, and my other airplane has a pretty tight cockpit - smaller than the Kitfox 7 SS I'm building now. I found that flying with some thin-soled moccasins works real well for me. It's amazing what losing an extra 1/2" or so of sole thickness can potentially do for your leg room and knee clearance. If you normally wear tennis shoes, going to some leather moccasins might make a big difference for you.

[Hockeystud87]

I revived my grandfathers KitFox 5 a year ago after sitting for over 15 years, I had to do all of the same things you guys have talked about. Carbs gummed up a few times before we got all of the crap out of the old tanks. Now i run only 100LL and have no problems with carb junk from the fuel tanks eroding away. I hat to have to do the work required to remove and install a new one. Cheaper for the short run to burn 100LL. Last thing i need to do the the engine mounts... some day soon.

I was talking to my grandfather and he stated he has always used, or tried too use, non ethanol gas. He runs auto gas in his. So I would assume this would help with the fuel tank erosion.

He stated he put all new lines in due to this very issue but that was some maybe 10 years ago. There is a slight green coloring in the lines I can see but is not heavy. Is this something to be of concern? Also he has a inline fuel filter installed for the engine. I'm guessing this will help greatly as long as it is cleaned often.

[Hockeystud87]

Don't stress too much over controle throws,full back stick is required but side to side full movement is seldom required as these aircraft have good roll authority even at low speeds:)

I was watching some in flight cockpit videos of other kitfox's and I was noting that they don't seem to need much for their roll authority and they don't seem any more compact than I was in there. I have full elevator and no issues with rudder so I assume once I know how the plane flies I can gauge the actual need for control. I'm starting to feel better about flying the plane!

[Hockeystud87]

I'm about the same size as you, and my other airplane has a pretty tight cockpit - smaller than the Kitfox 7 SS I'm building now. I found that flying with some thin-soled moccasins works real well for me. It's amazing what losing an extra 1/2" or so of sole thickness can potentially do for your leg room and knee clearance. If you normally wear tennis shoes, going to some leather moccasins might make a big difference for you.

This is great advice! I actually learned to fly the Cessan 140 with my shoes off. So that might also be another route to take. I'm starting to get more and more comfortable with the feasibility of my flying the plane. Seems like the biggest things are rudder and elevator.

[kmach]

I would replace all the fuel lines, coolant and oil lines, rubber carb flanges,get the carbs cleaned and rebuilt. basically the rotax 5 year rubber replacement.