This is the message that I tried to send Keith Baker but the email is bouncing. Maybe someone else can answer my question?

Keith,


I finally had the chance to fly my rebuilt motor last night. The power was awesome! The first flight was a little rich without the cowl on so I leaned it (2 degrees high and low) and put the cowl on. I got about 4 minutes of flying with the engine purring before it quit during a transition from 1/4 to half throttle. On the ground (after my knees stopped shaking, approx. 1 min.) we lasered the cylinders and left side was 205 deg. and the right was 185. Do you know the optimal cylinder head temp?
My plan is to baffle the cown and richen the low end? Does this sound right? Thanks for a great engine, I'll send you a photo for the website when I get them, T/R on maiden flight...

Thanks,
Chris

I believe that right around 200 deg is optimal. It sounds like you may be a little lean on the break in runs. Try starting with the high needle at about 1 1/2 turns out and the low needle at around 1 turn out. Peak your high needle rpm and back off 1/4 turn from peak. Set your low needle so it is rich enough to shut down the engine with the radio throttle stick. If it doesn't want to shut down, you're too lean on the low end

A question or two for you,

Why did you lean out the low end?
WHY did you lean out the high end?
WHY do you think the transition from low rpm to higher RPM changed after you leaned out the needles?
WHAT made you believe that the engine was rich with the cowl off?
After making your adjustment, WHY did you put the cowl on?


To me, you made TOO many adjustments all at once. When you think you have a problem, it is best to do one thing at a time. Yes sometimes it does take a combination of things to get to optimum, but you will see changes for the better or worse as you change just one thing. For the fact that this is a new engine, I would run it SLIGHTLY rich for a while anyway. You said it was rich....did you come to this solution with a tach and adjusting the needles or by the color of the plug? They way you need to set it up is to adjust the low end first for a decent idle, then adjust the high end for peak rpm, then check/adjust the low end again, then check/adjust the high end, then the low end, then the high end and so on until you have gotten optimum at both ends. While youare making these high and low adjustments, you NEED to check the transition. Once you have EVERYTHING set, SLIGHTLY richen the high end and check once again for good idle, transition and a good high end. After running the engine a bit, you can check the condition of the engine by the color of the plug. A black elctrode= too rich, a white electrode=too lean, a TAN electrode is just about perfect.

Ask yourself WHY DO I NEED TO ADJUST THE LOW/HIGH NEEDLE before you do it. If you can come up with a logical reason, then you are probably on the right track. Temps look OK.

Good luck

I doubt the value of the measuring - run it listen to it - make sure it NEVER sags going up -but hits full power
If you get both heads to read exactly the same - look for a star in the east --

Why did I lean the low end? Slow sloppy transition from idle to half throttle.
Why did I lean the high end? Burbling at full throttle that cleaned up only during a vertical.
Why did the transition change? I'm guessing a greater air to fuel ratio, leaner mixture, which did not load up the cylinder like the previous setting.
The motor was obviously running rich without the cowl on. BME instructions recommend turning the needles 1/16 of a turn at a time (22.5 deg), my adjustment was 2-3 degrees.
After adjustments the transition was good and full throttle was strong without sagging. After 4-5 min. the motor got hot and quit during a low-mid throttle transition. After a couple of minutes the cylinder temps were 205 & 185 leading me to think that in addition to extra cooling, I needed to richen the low end.
Yes, I obviously made too many adjustments which is why I asked the questions in the first place.
Dick & Silver Surfer thank you for answering my question, as usual you have been very helpful.

Chris

didn't my info seem helpful? How bout the tips on plug color?

As it turns out, my problem was the ignition. My minute adjustments were all within range and after flying it Sunday temps were normal too.
Keith told me today that some C&H ignitions built after Sept. 02 were suspect. The engine was very hard to start, even with a geared Miller on 24v. We checked the plugs and spark was weak even with proper gaps.
I did baffle the cowling and it looks good. Cylinder head temps were within 10 degrees of one another.
If I get more than 4 min. per flight I'll report back on the plug color.

Thanks,
Chris

Nice plane Chris, good luck getting the bugs worked out!

Floater.

Sweet plane and covering scheme. I hope Kieth gets that engine kickin.

Joe

I got my ignition back from C&H a week ago. Reset the needles to BME suggestions and it fired right up. Running real rich it flew great... right up until that last tumble when the hatch let go.
Total time on engine: 22 minutes.
We recovered the hatch and I installed 4-40 blind nuts with JB Weld to secure it. Flew it on Sunday at an airshow where the throttle pushrod bound up. The keeper nut on the threaded rod vibrated loose, slid down the rod and screwed itself onto the threaded portion that's screwed into the nyrod. It bound up on the nyrod sleeve so the throttle wouldn't go below 1/4. Guess what? The plane climbs out of torque rolls at 1/4 and I get 12 minutes on 32 oz. before it runs out of gas! I pranged the gear and a prop.
Total time: 34 minutes.
I repaired my linkage and flew towards the end of the show. The engine is awesome! Still rich but it looks like it's on a rubber band in the torque roll, it doesn't just pull out it bounces out.
Total time: 43 minutes.
The gear has been replaced and I'm ready for 3D night but it's raining....
There are some more pictures on our club website, it's being built but the gallery is up:
www.ribcrackers.org
maybe now I'll start leaning things again, right after I check the plugs...