Always nice when you meet the right people for a job. The guy who works on my motorbike I sometimes have to slap over the head so that he doesn't forget to charge me what I owe him - he just likes the bike way too much.

Great story Dart.


Wheels

Case is together, ready for pistons, cylinders, manifold, etc.

I know that you made sure that the case halves were put together correctly.
They weren't on my Sonex. The engine developed an oil leak because of that that drove us crazy trying to find.

Gratuitous engine pictures!

Everything cleaned, crankshaft and camshaft put into place, time to mate the cases:



Lots of careful fitting together, but it's looking pretty good.



We actually had a minor mishap where the ancient ring compression tool used to put the pistons in the cylinders wasn't cooperating and we wound up breaking a ring. Sigh.

So I got a new, better tool and a new set of rings. Pretty expensive lesson on why getting frustrated and whacking things isn't the way to go.

But she looks pretty engine-y.



Loads to do, of course, including mounting accessories, the prop hub, valve thingies, etc., but things are really looking up.

Thursday the guy in Georgia with the extra brakes and wheels from his Nieuport projects, and hopefully that big gaping hole in my "repair the problem instead of just fixing it" plan for my airplane will be solved.

What compound did you use as a case sealer for the case half? 3Bond is the maker for most of the motor bike manufactures (Yamabond, etc..). I hate the old school Permatex 2b, but RTV silicon would be the worst possible choice.



It is not hard to break pistons and piston rings. I still try and do them by hand and that is how I will be doing it on the GS1100 mono block this week. Yes it is a pain and takes a lot of time and patience. I learned long ago that the force from your hand mashing down on the cylinder can break the ring lands of a post 80s design motorcycle engine. The KTM RFS engine has a very strong oil ring. Believe it or not, 2 worm style hose clamps with the screw adjuster 180 degrees apart works better then most special tools. KTM says to install the piston into the cylinder and then fit the wrist pin. Austrians must be very strong. Fitting there super thick wrist pin clips is hard enough with a just the piston. Installing a piston from the top allows for most any ring compressor. That is not possible with most roller cranks. crap, I am rambeling

About your cooling...
Could you put a small tube (1/2 or 3/4) in the cowling that would trap some of the fresh air and direct it behind the front cylinder?. It would not take much, in fact too much could cause a cold seizure. Your main problem is that the hot air from the front is what is used to cool the rear.

I don't think a tube would help to get air to the front cylinders...

The only solution I can think of would be making the cutout in front of the cowling a bit larger. Might ruin the looks, though. And of course, might weaken the cowling structure. Is there any way that you can design some baffling into that cowling?

Actually, it is baffled. The engine is split horizontally - note the aluminum sheeting across the front - with the baffling. This causes a high pressure area on top of it, forcing the air down through the cylinder heads.

It may be a simple as cutting down the lip that goes across the front there.

Yeah, that could work as long as it doesn't weaken the cowl and cause it to vibrate. Got a wind tunnel nearby?
I'm kidding but I know it must be frustrating. Have you been on homebuilding forums to ask how others solved the problem?

The consensus within the Nieuport 11 community is "Yeah, weird, huh? If you figure it out, let me know. If the engine is running within tolerances, don't worry about it."

Out of pure curiosity I did some searching and found the following page, I don't know how applicable it is in your case but looks like good info anyway.


http://zoomaviation.com/engine/vw_type_1_&_2/baffle_&_cooling/how2_keep_vw_cool/

Forgive me Dart if I saw you comments in another thread about heating of a back cylinder and hijacked this thread. Air flow is almost the same as water flow. You can see water, but you can not see air. For the basics think of water flow and not air flow.

Your prop spins in a given direction. The heat (air) is moved back and away, following the direction of rotation. The air flow under the cowling is trapped at the back if you do not have some outlet for the pressure differences. This is dead air space. Spray your garden hose into a bucket. Note the direction of the returning splash.

Does this description match the rear cylinder in question? If it does, then you only need poor fitment (or a purposeful air gap) on that corner of the cowling to let the air flow.

Actually, it's the front cylinder that ran hot.

The one that is getting the airflow directly coming into the cowl.

You mentioned that you could tell that this cylinder was running hotter then others. Did you mean that you could see a difference in wash across the top of the piston, or did you mean that you could see smoothing (wear) on a given cylinder?

Then that is heat expansion of the piston against a cold cylinder. You are over cooling that cylinder.
You need to baffle air flow away from it.

It may be as simple as a shield in front of the cylinder to limit the prop wash directly onto that cylinder.

Is this the front cylinder that is first in the prop direction of rotation? The opposit cylinder should pick up air turbulence and heat from the engine cases.

if you want a good example of air cooled cylinder problems look to the Yamaha YZ/WR 490. Even if you have the correct jetting, the owner can easily seize the piston. What a pain that motor was in CA. Run it outside of sand and elevation changes, she was stable, torque personified.

The IT465 had similar problems, but that was more due to fuel starvation at higher power levels, the standard Yamaha tap on the tank could not flow enough petrol to keep the float bowl filled and that lead to over heating due to a weak mixture, instantaneous throttle response was fine but anything more than a few seconds at full throttle then the piston melted. It had happened to quite a few IT465 owners I knew, including me, 6mm drill on the tap and I never had any more problems after that.

Alicatt,
That is the same engine family. I stand corrected by your real world experience. Your tale sounds similar to the problem with the 88-89 Yamaha EX 570 snowmobile. It took 3 years for the experts to find that the problem with the VM carbs was caused by air turbulence from the secondary clutch.

Gosh darned it.*

I went to put on the shrink prop hub and the worst thing happened - it went on halfway and stopped.

Tarnasions! Golly gee!

When this happens there is only one thing to do - tear the engine back down, remove the crankshaft, and very, very gently take a puller and get it back off. Fudge.

The woodruff key was a smidge too tall in the back.

Fuss and bother!

The upside is that Dave's ever so slow methods really made soaking in all he taught me sink in, and in about an hour and half I had the engine torn back down. One of the airport guys had a puller, and it came off okay without damage to anything.

Many, many measurements later, a little work on the belt sander, and the key is back in. I'm going to re-polish the crank where the prop hub goes on, make sure there's no burrs in the prop hub, and give it another go tomorrow.

Rassle-fassel.

* I may have used words similar in sentiment but slightly coarser.