skypics

I have an avid MK4 heavy hauler with the STOL wings and two 14 gallon fuel tanks.
When I 1st had the model B I could burn mogas with MTBE until it was outlawed. I soon found that the ethanol laced tanks can't handle the ethanol because it softens the resin in the poly ester tanks. At some point I know that Kitfox changed to polyvinyl tanks and was wondering if Avid ever changed and if so...when. My avid was built in 1996.
A friend, Joey says he has been using California mogas for years in his MK4 with no issues. So, this has me hopeful that maybe my tanks will handle mogas.
I run a Jabiru 2200 85 HP engine which can except mogas at 91 AKI. 
As a test I have drained the avgas from one tank and put in two gallons of 91 mogas. I will fly on the avgas in the other tank, and I will drain a little out of the mogas tank each time to see if the mogas starts to turn yellow...a sure sign that the resin is softening.
Let me know if anyone here is using mogas.
Two airports near me in SoCal have banned the sale of 100LL and the public is becoming more concerned with the lead we are using even though aviation gas accounts for less than 1% of the motor fuel used in the US. That coupled with the fact that the only supplier of lead tetra ethyl is one producer in England. If that plant goes belly up GA is SOOL.
John M

Is there a drop in replacement tank for the Avids that is ethanol proof?
 
John M

HI;
Haven't been on this forum in a looong while. Just want to catch up.
I have had two Avids. A model B which I destroyed on an difficult High Sierra strip. Bought a MK4 with a Rotax 582 2 weeks later. It has a bit more cabin room.
I saved the Gen 3 Jabiru 2200 from the crash and installed it on the MK4. The prop, mount, spinner and engine were purchased by a man who drove down from Montana to SoCal to pick it up.
I have over 6,000 hours in Avids and have been completely satisfied with this aircraft which makes me wonder why a business could NOT succeed in the sales of this kit.
I have been through 4 Jabiru engines. I have had 4 engine failures in that time. Two were exhaust valve failures, another threw a rod 30 seconds after i fired it up. It had been repaired by a dealer near Fresno. He did replace that engine with a newer one. Finally, my new Gen 4 fragmented at 170 hours and was replaced after 3 months by Jabiru Australia.  
The replacement engine exhibited a very high EGT  on #2 which turned out to be a manufacturing flaw where the induction tube goes into the cylinder. The land that the o ring rests on was much narrower at the 7 o clock position. This caused distortion of the O ring. The O ring is BUNA-N which is only good to 225 F do I replaced it with a Viton O ring that can handle over 400 F. 
Jabiru would not replace the jug so I had to install a thin shim washer on the o ring land to provide a secure placement. The EGT is now much lower, but still higher than the rest.
I run a Whirlwind 66" 2 blade set to give 2880 on climb out from my 533 MSL field. My climb rate solo with 12 gallons fuel is 1200 FPM. With 28 gallons climb is 900 FPM.
I recently flew to Big Bear airport (6750 MSL) and filled it up to the top with 28 gallons. DA was 8900 at take off and I could still climb at 500 FPM only turning 2750 RPM. I leaned out on climb out and got an extra 30 RPM and a climb of 600 FPM. What a fabulous bird!
I do not prefer the Rotax 912 due to the extra complication of gear boxes, spraug clutches and water supply parts. It is heavier and replacement part are way over priced. I can only imaging how my climb rate would improve with 100 HP, but am not willing to change since this engine has gotten me in and out of many Idaho backcountry strips.
I don't expect to be flying much longer as I have just hit the 84 mark on life's journey so I'm hoping this engine will last till I hang up my headset for good.
Fly safe...stay healthy.
John M
 

Does anyone here know when and if Avid started using a different resin for the glass tanks.
I wanted to use 91 AKI in my Avid MK4 for all my short (1.5 hour or less trips) so I installed a marine outboard 6 gallon tank on my passenger seat .
I can easily switch from the seat tank to the wing tanks.
Borescope photos are showing that the lead accumulation is flaking off of the top of the piston so it is doing what I want.
Then I remembered that Avid started using a different fuel tank fiberglass formula, but don't know what serial number. 
Anyone know when they changed over?
As I recall the new tanks looked white inside and the old were tan.
Still enjoying flying my Jabiru powered Avid after over 5,000 hours.
John M
 

This new engine has improved and resolved all of the earlier issues with the top end of the engine.
1) Smooth idle down to 600 RPM
2) No added oil between il changes
3) Larger cooling fins keep CHTs low
4) Starts instantly without using the choke.
5)  Oil stays cleaner longer.
Finally: Why does clicking on some subjects on this forum take me to a pharmacy advertisement?
John M

 
I think I have posted about this before, but it needs repeating.
 
I have pulled the heads on my Jabiru 2200 several times and each time I have had this problem.
 
The hydraulic lifters on the pulled head do not relax after reinstalling the head.
 
This causes the valves, sometime only one, but many times both to be partially opened.
 
You will be able to see this by comparing the position of the valves on the head you didn't work on. They will not be as far out and near the edge of the rocker box edge as the untouched head. 
 
So when you turn the prop by hand you will find one cylinder with no compression. If the intake valve is held open too, you may see one of the other cylinders with no compression because of lack of vacuum.
 
If this happens you have a couple choices:
 
A) remove the head again and pull the lifters and soak them to get all the oil out. You should be able to compress them when they are clean.
 
B) Start the engine and let it run roughly until the oil temperature builds. This can take 5-10 minutes. You should see the EGT start to build on the soft cylinder and then after the oil is heat soaked the hyd lifters will relax and the engine will smooth out.
 
Flew it for an hour for check out. All is well now.
 
John M

A friend is dealing with lung cancer and is selling his Zenith 750 powered with 912 ULS. 
Engine and airframe have 259 hours.
Sharp looking paint scheme.
Larger tires for the backcountry strips.
He is asking $69K
John M

This head will fit the #1 and #3 position according to the oil feed lines to the rocker box.
This is the newer head with 21 smaller fins.
Contact me for a photo.
John 

It's been just 21 hours so far after installing my new Jabiru Gen 4 2200.
I have flown behind 2200s for over 3,000 hours and in that time I have had a sucked exhaust valve, a displaced valve seat and relined my valve guides 3 times. Of course, this also happens to "real" aircraft engines. That said, I have always thought that while the bottom section of this engine was very robust, the top section had many design flaws caused by inadequate rocker box lubrication. 
This causes early valve guide wear which causes sloppy valve positioning which can result in valve head separation.
In contrast to the earlier generations, the Gen 4 appears to have addressed these flaws with;
A) Larger fins
B) Head and jugs are now cast aluminum instead of CNC. This allows tighter tolerances since the piston and cylinder are of the same material.
C) The rocker boxes are lubricated up through the pushrods where the oil moves into the rockers and to the rocker bushings. 
D) The engine starts every morning in two blades without using the choke. When warm the engine starts instantly. I believe it may be hand propped. I will try this soon.
E) The engine can idle smoothly at a mere 600 RPM.
F) After tweaking the air duct to fit under my Avid MK 4 cowl, all CHTs and EGTs are well within specs as recently tested on a long climb out from 533 MSL to 9,000 MSL at full power.
G) After 21 hours the oil still looks clean and still is at the dip stick full mark.
H) There is only a tiny bit of water/oil collection in the breather bottle.
I am swinging a Whirlwind 66"two-blade prop.
So far I am well pleased with this engine.
I did have to buy a new engine mount since the new engine moved the top two engine mounts 15 mm to clear the larger fins.
The new mount cost $895. I sold my old MK 4 mount for $300.
Sold my old 2200 for $2K.
The new engine was $15K plus shipping.
John M
 

What happened to the Avid MK4 section?
John M