2013 Updates

Late February of 2013.  I took the KR out for a nice warm up flight and was once again so pleased with the way this plane flies, and the way this engine runs.  I have a number of updates I'd like to do to the plane, but just can't stand to ground a plane that flies so nice.  By afternoon, that tune had changed.

I pulled the plane in to start on what should have been a quick and easy annual inspection.  First thing was to do a quick compression differential check.  Nearly perfect, 79/80, 78/80, 79/80, and 58/80.  What?  That can't be right!  I checked a little closer and the news was not good.  It was leaking past the rings.  That does explain why the engine has been  pushing a bit more oil than expected.  One of these tired old  +.015 over cylinders has finally given up.  Surely it must be a broken ring.  I pulled the cylinder and saw nothing obviously wrong.  But measuring the cylinder, it has gone well beyond service limits and was showing some cylinder wall distortion.  It's time for new cylinders.

So, I got in contact with my friends at Aircraft Specialties and ordered a new set of Superior cylinders and a set of O-200-D pistons (8.5:1 compression rather than the 7.0:1 compression in the O-200-A).  Wow!  That was a surprise.  I didn't think Continental was going to make those pistons available.  I got into a real snag with the rings as Continental changed the top ring in the D pistons, then made them pretty much unavailable.  Finally resolved it by having my friend Doug machine the top ring groove to fit the ring set from the C-75 through O-200-A ring set. 

Now that the plane is already down for major maintenance, it's time to do all those little things I've been thinking about ever since the last major refit in 2005.


Feb 24 - #4 cylinder all the way to the right is the one with failing compressions, but what's up with #3?  That
would be the same rocker boss that was broken in 2008 that I had welded by a cylinder shop and is obviously
broken again.  These cylinders are going into retirement and will not fly again.

This is as far as I'll tear it down this time.  I did replace the mount bushings while the engine was stripped down.  
One may note that this engine has the adapters to allow me to use the less expensive A and C series mount

March 2 - Here is a side-by-side photo of the 8.5:1 compression O-200-D piston on the left and the 7.0:1 O-200-A
piston on the right.  Note that the new piston is now down to 2 compression rings like most other pistons in the world.
One other note on this... Continental used a unique tapered ring for the top ring, then made the rings darned near impossible
to get... or afford.  We machined the top of the top ring groove straight to fit the original C series/O-200-A ring set.

Update: 1 year later at annual inspection the compressions are all in the high 70s, so machining the ring groove for the straight
ring rather than the high dollar tapered ring seems to work OK.

Update: 2 years later the compressions are 78/79 over 80 all the way across and the oil consumption is roughly 1 qt
to 20 - 25 hrs.  I couldn't be happier!

March 9 - Engine back together with Superior Millenium Cylinders.  We did a little tune up on these new
cylinders.  A three angle valve grind on the intakes to help the engine breath a bit better.  Also radiused the
intake ports as Superior left very sharp edges where the intake makes the 90 degree turn to go through the
valve.  I have bought several new Continental cylinders for O-200 overhauls.  Hands down, the Superior
cylinders are the best.

May 4 - What's up with the automotive plug wires and spark plugs?

Hmm.  That's not a magneto.

That tag says Emag.  Actually these are Pmags, so are self powered once the engine is running and will add
a timing advance curve to the ignition.  For engine break-in, I'm going to use the more conservative advance
and limit the timing to 34* advance to keep the temperatures down.  Once the engine is broke in, I'll likely go
to the less conservative timing curve and allow it to go to 39* advance.

Update: After a year of operations, I find that I usually run the 34° advance unless I am headed out cross country.
With 39° advance climbing out at 7500', #2 CHT runs a bit warmer than I like to see (425° F) unless I am careful
to keep the speed up in the climb.  At cruise, all 4 settle in nicely at 275 - 300° F with either advance setting.

Next update:  After another year or operation, I finally found an air flow issue with the cooling on #2 cylinder.  It
has taken me 18 years to notice I had 2 spark plug leads laying across a critical cooling area blocking the air flow.  
Once that was addressed, I now use the 39° advance curve nearly all of the time.  

May 8, 2013 - First ground run on fresh top end and Pmags.  My first impression:  The engine sure starts fast with
the Pmags.  It also idles incredibly smooth.  With the higher compression pistons, I was really expecting  the
idle to be a bit rougher.  Instead, it idles as smooth as my Honda car.  It's pretty clear that the Pmags must retard
the timing for idle.  I shut off the power to the Pmags and found they will self power down to 700 rpm.  Below
700 rpm, the engine just stops unless the Pmags are powered.  Pretty much as advertised.  Log books are
completed and the aircraft is now ready to fly.

March 2016 - The right side Emag has failed twice now.  The first time in Aug 2014 was an edge connector where
the coils plug into the PC card.  I stopped to refuel in Western Kansas and found that half of the right Emag was not
firing.  I scrapped the rest of the trip and returned home with one ignition only firing on 2 cylinders.  Emag repaired
the Unit free of charge.  

Notice how close the mounting bolt is to the connector in the mirror?  Emag thinks I may have damaged the edge
connector by bumping it with a socket during installation.  I don't think it happened, but it is possible.

The second failure had the head of the Pmag come loose from it's mounting flange.  I suspect the guys at Emag
failed to torque the internal screws properly when they repaired the failed edge connector.  First failure was at
60 hours.  Second failure was at 166 hrs.  Once again, the guys at Emag fixed it for free and also performed
an inspection on my other Pmag for free at the same time.

April 2016 - As long as I was already grounded for the Pmag failure, I needed to do some other work as well.  
My old Delco Pull type starter had the sprag clutch failing again.  I found an acquaintance that was selling a B&C
Light weight starter along with a Plane Power Alternator from a C-85 that was going onto his Cub, so I bought
them to upgrade my O-200.

April 2016 - Old and New Accessories lined up together.  The changes lightened the engine by 10#.  20 Amp Delco Generator & 50 Amp
Plane Power Alternator.  Delco Pull type Starter & B&C Starter.  Mechanical Voltage Regulator & Plane Power Electronic Voltage Regulator.

Part of the installation of the B&C starter requires cutting off the starter gear pinion shaft from inside the accessory case.  I fabricated a shield
that fit over these gears, but any way you do it, it's an ugly job that is going to throw contaminates all over inside the accessory case of your engine.
I washed down the insides of the accessory case 4 times trying to get all the contaminates out of it.  An hour later I pulled the oil screen.  It had
some stuff on it, but wasn't too bad.  

New problem.  The nice highly efficient, high torque B&C starter spins the engine like it's idling, but pulls the system voltage down low enough that the
Pmags won't fire.  I could walk around and flip the prop and the engine would fire right off.  I need a battery that is the same size or smaller than the
YB-16 series motorcycle battery in the KR, but puts out a lot more cold cranking amps.  About the only way I could go is with a LiFePo Lithium
battery.  I installed an EarthX ETC680C which is less than half the size of the the old Motorcycle battery and with the Aluminum battery box and two
1x4 blocks to bolster the battery weighs in at a whopping 4 lb, 3 oz vs the 14 lb weight of the old YB-16 Motorcycle battery and Fiberglass cover.
I have now removed 20# from in front of the firewall.  That moved the CG aft a bit, but the plane is still in the proper CG range.  However, the engine
now spins even faster, and also starts!  (YB-16 battery = 175 CCA for starting.  ETX680C = 320 CCA)   

Feel free to email me with comments or questions at jscott.planes"at"gmx.com.

Stay tuned.  More to come...