109jb

Got the bottom case of the engine apart today. Everything looks great inside. Very clean and no sign of corrosion on anything. I'll replace the two outer crank seals and get the engine back together once My Loctite 574 arrives. Right now it is sitting there upside down on the cylinder head nuts with a clean towel over it.

Hi Doug,
I started with the technique at http://wienerdogaero.com/Latex.php but I have since modified it. He does all of the primer coats as brushed on coats, but I only brush the first coat.  All coats of both the primer and the topcoat are thinned with plain old water. I thin just by guess or by gosh, but it is about 3 or 4 parts paint to 1 part water. Basically as thick as possible but sprayable through my gun. So, here are the steps I used:
1. Brush on a thinned coat of primer (PPG Gripper) with a foam brush. I really slop this on to make sure to get good penetration of the fabric and then "tip" it with the brush to even it out. It dries fast enough that I go back over the tapes an additional time before calling the first coat complete.
2. Once dry, I lightly wet sand the entire fabric area, but spend a little more time on the tape edges. Be careful not to sand over hard structure. It is easy to sand through.  Once sanded, I use a pray bottle of water and lots of paper towels to clean the fabric.
3. From here, I proceed to spraying the rest of the coats.. I use a cheap Harbor Freight HVLP sprayer https://www.harborfreight.com/air-tools-compressors/air-spray-guns/20-oz-hvlp-gravity-feed-air-spray-gun-62300.html .  I thin the primer and spray it on. I put on about 4 or 5 coats letting it dry between coats. If it is warm you can do these coats in a day.  I don't sand anything between each coat except the pinked tape edges to get them looking nice. I only sand the pinked edges that aren't smooth, not all of them. By the last coat I don't have anything tape edges to sand. All sanding I do is wet or dry paper, about 400 grit.  
4. After the last coat of primer I do wet sand lightly, just to get the little bit of orange peel off. If you thin the primer, it goes on with orange peel but most of the orange peel flows out as it dries. I sand the primer where it ends to blend into the existing paint.
5. Now the top coats.  Since you are doing a patch job, you might be able to do like I did. tried the computer color match twice but both sucked.  One was too light and one was too dark. I wound up mixing them to get a perfect match. Took some experimentation, but I would up with 3:1 ratio of the light to dark.  If I had to do it again, I would just go to the paint store with a scrap of the old fabric and pick out 2 colors from the paint card, one a bit darker and one a bit lighter and do the same as I did on this airplane. Anyway, once you get the color right, thin it the same way and spray the same way. Just be careful as the topcoats seem to run easier than the primer. If you do get a run, "tip" it with a foam brush and it will almost disappear when it dries.  In my case, I had to do many coats of topcoat because yellow is horrible to get to cover. That is also why I didn't get the primer tinted and left it white. You will be in the same boat. I just kept putting coats on until the yellow finally did cover and blended into the existing color. I think it took about 4 or 5 coats. In my case I didn't sand between these coats because it flowed out relatively well and my purpose on this airplane is mainly to get it back flying. It has a little orange peel, but is good enough for me. If you look at the link, he color sands and buffs to get a real glossy flat finish. I'm not doing that, but I will buff the blend area a bit. The only time you can seen the blend on mine is when at the right angle and you can see the overspray area. Once buffed in that area I think it will disappear.
Spray gun cleanup is a breeze. I have a laundry sink and hot water in my barn, so I just rinse the cup out real good, Spray a little straight water through it, then disassemble and rinse better. It takes about 5 minutes I'd say to clean the gun. I just run hot water through all the pieces, use a little plastic bristle brush (looks like an industrial toothbrush) on the external components. The hot water gets all of the latex out of the inside of the gun. Super easy compared to something like catalyzed urethane.
That's my method on this one and is also the method I will be using for the wings on my other airplane. Good luck with yours.

So I found something  unusual.  I got the pistons cleaned up and back in the engine and since I have the gearbox and flywheel off I performed the leak test again. Still leaking so sprayed soapy water on the PTO end seal and it leaked. So what you say, right? Well it wasn't leaking around the crankshaft or around the crankcase. It was leaking in several locations in the face of the seal With the seal out I could see that it was leaking at locations where there is only rubber on the face. The steel face behind the rubber has several holes around it (6 or 8 I think) and it was leaking from most of those spots right through th face of the seal. 
So I pulled the rotary valve cover and will be removing the magneto components and splitting the bottom of the case, keeping the cylinders and heads on. I'll replace the outer o-rings and the mag side seal while I'm in there, so it should all be good once done.

Only one picture this time.  I had to go out of town for a few days but did get the cylinders and pistons off.  The bottom rings on both pistons were stuck at one location around the groove, and there was a lot of carbon buildup on top and in the ring grooves. No damage done but it would not have been long. The 
I made a piston pin puller and some delrin plugs to keep the cageless bearings in place when  removing the piston pin. Worked great. The delrin plugs will really aid in putting the pistons back on too. Below is a picture of the whole pin pulling setup. On one end is the black delrin plug.  It is just slightly smaller than the pin at 0.705" diameter, 0.9" long. The length is long enogh to retain the loose bearings and the little thrust washers on either side of the bearings and yet still allow the piston to be removed/replaced. On the right in the picture is a piece of 7/8" 4130 tube with a washer with a 1/4" hole welded to the end. In my case I had a slug from using a hole saw. It also has a little notch cut so that it can clear the little shoulder below the piston pin bore on the piston.  You then need four 1/4" nuts and a piece of 1/4" all thread. Pull the circlips, then the all tread through the piston pin, the delrin slug and a nut on the other side, and crank it just far enough that the delrin slugh is inside the thrust washers, bearings and other thrust washer. The double nuts are for a wrech to prevent the all thread from spinning. You could just bend a L on the end of the all thread. Once the delrin is centered in the rod bearing, loosen and remove the other puller components and pull the piston off. The delrin slug remains insid the bearing in the connecting rod and the bearings are still in their exact same position.
Pulled the C-gearbox too. Very clean inside and no problems noted except for a bit of rust on the back end of the prop shaft. Polished that with 1500 grit paper then crocus cloth. FYI for anyone interested, a $15 Harbor Freight "steering wheel puller" worked fine for removing the PTO side flywheel. I call this kind of puller a harmonic balancer puller, but whatever name you call it it works just fine. Came with a perfect size end for pushing on the crank end without buggering the threads. Had to get 3 longer 10mm bolts for it though.
 
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Thanks Sed.  Its not a real rush. Let me know what you want for it.

Don't happen to have a spinner for a 3 blade prop do you?

Actually it looks like 7 inch diameter

He posted in the Kitfox V forum, so I assume that is what he wants.

Finally rolled the fuselage outside in the sunlight to see how the paint match came out.  It came out a little dark on the fin and rudder, but the fuselage is perfect. The fin and rudder were the first to get sprayed and I saw it was just a tiny bit dark and adjusted the mix. Even the fin and rudder aren't noticeable unless you are looking for a mismatch, so plenty good enough.  Have been working on little projects. Mounting the com and ELT antennas. Didn't like where they were previously. Repairing a little damage to the trailing edge of the landing gear fairings. Replacing rotted hoses on pitot static system, Replaced the corroded ELT batteries with new and cleaned the battery contacts. Painted the cabin to wing closeout fabric, and cleaned the shop. I have my engine parts on order, so the engine comes out tonight for new seals and a decarbon of the pistons. I've already pulled the head and the cylinder bores look great but the pistons do have a pretty thick coat of carbon on them. Not sure what he was using for 2-stroke oil, but I've been using either full or semi-synthetic oil in my snowmobiles with great success. Both seem to burn cleaner leaving less carbon buildup. Will probably drain the oil tank and replace what is in there now. Good news is the coolant when I drained it was orange, so he was running Dexcool which means the cross shaft seal is probably good. Once the engine is done, hopefully this weekend, the wings can go back on and it will be ready to fly. It may fly before I paint the cowl as that is just one piece that might even be easier once the plane is moved to the airport and I have a bit more room in the shop.
 
 

Never mind. After more research it appears that the thermostat, when it opens to allow flow to the radiator, it has another disk to close off the flow through the bypass hose.

Thanks Yamma-Fox.  I'm very motivated on this project and am in "don't think too hard., Just do" mode.
Got more done today. Got the patches on the horizontal stab painted last night, so today I installed the tail surfaces for the last time, Installed the tailwheel and redid the springs because I didn't like how the previous owner did them. I also installed the cabin root ribs, made a windshield and installed it (Fits perfect), and started the fabric on the closeout between the fuselage and root ribs. Once I paint those the doors will go back on and it will be essentially fixed except for the engine stuff. Later tonight I'm going to pop the cylinder head off to make sure it is still standard bore and will order the top end kit for the 582.
 

I could get you the measurements for a kitfox 4, but not a 5. If those will help,  let me know and I'll measure it up.

Aft fuselage damage done. Paint looks like a perfect match in the shop. Tomorrow I'll roll it outside and see how good it is. Next will be re-installing the root ribs on the cabin and making a windshield. At that point if the wings were on it could be considered airworthy but I have a few more things to finish, Mainly finishing fiberglassing the left wingtip damage, the front upper cowl and painting those. I also have to replace the seals in the engine, but it is getting there.

Interested in the kitfox 4 flaperons. Are they new, used, condition, and where are you located?

Hi TJay,
I'm doing the repair on this airplane and all the cover on my other Kitfox using the process described in this link:
http://wienerdogaero.com/Latex.php
So I start with applying the fabric and tapes using Stewart's Systems Ekobond.  Actualy I'm using 3M Fastbond 30NF contact cement which I'll talk about later.
I have also covered my Sonerai using the complete polyfiber process.
As far as attaching the fabric, Ekobond is super easy and I much prefer it to polytak. It is not nearly as messy, doesn't smell, doesn't cause me headaches like Polytak, etc. Before "locking" it down, the fabric can be positioned temporarily while held loosely by the glue, repositioned as much as you want, and then locked down with an iron on low heat (225F). When I did my Sonerai I remember using dozens of clothes pins to position and hold the fabric for applying the Polytak. So far covering the parts of this airplane and also my other Kitfox I have not used a single clothes pin, clamp, or anything except what the Ekobond/Fastbond provides.
On to applying the tapes. If you have used polyfiber then you know the tapes go on with polybrush. I was never thrilled with how polybrush worked for applying the tapes. It always seemed difficult to get them to lay flat, and especially doing the control surface leading edge tapes it was a pain. With Stewart's, the tapes are also applied with the Ekobond/Fastbond. Again, I absolutely love the way this system works for tapes. No clamps, very easy to do.
From this point is where the latex "system" I'm using deviates from the Stewart's System. You can read about that system here: http://wienerdogaero.com/Latex.php . I am very happy with how the latex finish is coming out on my other Kitfo, and I'm sure this one will go well too. As far as latex goes, my Sonerai got stained by bird crap on the polytone, which i could not get out. Rather than paint it with polytone or Aerothane to cover the stains, i painted it with Behr brand gloss latex enamel paint, and that was about 2016 and it looks as good today as the day I sprayed it aside from a few scuffs and scrapes which are not the fault of the paint.
As far as the rest of the Stewarts system, I haven't used it so can't say but a friend is and so far he likes it and has gone through finish coats on his tail surfaces.
I also can't say if the Ekobond/Fastbond is compatible with later coats of anything not waterborne. So I would not mix it with say polyfiber products.
In a nutshell, after using the Ekobond/Fastbond, I would not go back to the polytak. This is for ease and the lack of noxious headache producing fumes. If I wanted to do a complete STC'd system I'd go with Stewart's over polyfiber. I haven't used any other systems like superflite, oratex, Randolph, etc.
Now comparing Ekobond to 3M Fastbond 30NF. First, I read online that some had determined that the Ekobond was essentially the same as 3M Fastbond 30NF. So, I bought s quart of the 3M stuff and also got a bit of Ekobond from my friend using that system and did up a couple test frames including some tapes on those frames. They look the same, feel the same, act the same, apply the same, etc. I peeled the fabric off of both frames and unscientifically could not tell a difference in how well each product held the fabric. Based on this, I decided to use the 3M Fastbond. When the quart I bought was gone, I bought a gallon of it. That is what I'm using on my airplanes.

Tail modifications done and fabric going on them.
 

Well, I met my goal of having fabric on the fuselage by this past weekend. The fabric was attached using Ekobond and I'm using the latex paint method on the patches. I decided to do this after checking a spot of old fabric by cleaning it with acetone. There is obvious darkening of the paint over the years so even though I know the polyfiber color, new paint would not match well. Anyway, I've now got the weave filled and starting on color. Before anyone says anything the color on it in the picture below is too dark.  This was a computer color match but doesn't match. Since I'm using latex I went to the paint store and rather than refund my money, I got them to sell me another quart at 1/2 price that was tinted too light.  I've been experimenting with different ratios of dark and light paint and am pretty close to a perfect match using 2/3 light and 1/3 dark color. I'll get the exact ratio I need after a few more tries. In the meantime the dark paint is on as a base since yellow is such a pain to cover.
I also moved on to enlarging the vertical tail to match the size of later model 4s. I didn't know the fin leading edge tube was 0.049 wall thickness, so I had to order a new piece. Rudder was enlarged and instead of rounded corners I went with squared off corners.

Aluminum tailspring with hardware is $355 if bought new from Kitfox Aircraft

Got more done this week. Tubing finally arrived and I got the longerons fixed and side covering on.
Also had a crack at repairing the busted upper cowl. To fix this I simply used a cutting wheel on a dremel to open the cracks and allow the pieces to be pulled back into position. From there I used bits of tongue depressors and hot melt glue on the outside to hold the cowl in proper position. Then a right angle air grinder with roll-loc disks to grind down to bare clean glass and layed up glass on the inside. Used mostly 2 layers, but sometimes more depending on the area. Amazingly a trial fit shows it worked.
 

The pdf shows the  stiffeners in the top of the tank are round foam pieces glassed over. I personally would not do the sealed access panels in the bottom for several reasons.
As good as the access panel sealer is it is still a sealer that can fail. Looking up the specified sealer doesn't say whether the sealer is appropriate for auto fuel. It says it is good for aviation fuels but doesn't mention auto fuel or the additives that auto fuel can have that avgas doesn't. I could be wrong on this but a quick search of the manufacturer's website only showed "aviation fuel". If only using avgas then I guess it is fine, but if you ever want to run auto fuel I would make sure the sealer is good for it first.For a fuel tank, if I am going to cut a hole it will be in the top, even if using removable access panels. Even a small leak in an access panel can result in all fuel leaking out. A cutout in the top would only allow what is above the leak point to exit.A permanently bonded panel can be made to essentially disappear except for some pinked edge tapes which are very unnoticeable if done right. Although the access panels shown aren't "unattractive", they don't look as good to me as what can be achieved with a permanantly bonded and covered repair.Not sure on the undercambered Kitfox fuel tanks, but on the Kitfox 4's I have had the tank is 1/4 to 1/2" above the bottom fabric, whereas the top of the tank is flush with the airfoil profile. There are basicall false ribs on the bottom of the tanks.  Doing bottom access panels would either mean depressing the fabric around the panels, or putting the removable panels in the tank and then covering them up with fabric. To access them if covered with fabric would mean cutting out fabric anyway. I would think the Kitfox 5 is the same as the 4 since the wing is the same airfoil. 

Your jetting looks fine and you are loading the engine way more than you should have to in my opinion. Have you checked for air leaks?
On a 2-stroke, if the crank seals are starting to go it will suck air and start to lean. Likewise, carb boots cracked will do the same. Really anywhere there is a leak on the engine it will suck air and lean it. You can check by doing a crankcase pressure test. This involves blocking exhaust, intake, and fuel pump pulse line and pressurizing the engine to about 5 psi. It should hold that 5 psi for minutes. I just did this on my newly acquired project 582 and I have a leak. A little later I can get some pictures of my setup, but it is basically 2 plates drilled to block the exhaust and siliconed to seal, a pair of forceps to pinch the pulse line, and a couple plugs to go in the carb boots. One plug has a 0-15 psi pressure gauge, and the other has a tire valve stem. I use a bike pump to pressurize, not an air compressor.
This video shows what I do. https://www.youtube.com/watch?v=r-ffJVbpeAs&ab_channel=Paisteboy

Thanks. Just wondered if you had found a better/cheaper alternative.