Best piston/liner fit Baby Bee

Hello,
I am Roland Dieterle, located in the southwestern part of Germany. 59 years ago, my first engine was a Cox Pee Wee.
It gave my lots of fun and was a perfect match in the free flight Topsy built from a Graupner kit. Unfortunately, in a crash, the mounting lugs broke and I traded the engine for a Baby Bee plus 5 DM, which was about 5 months pocket money. This engine I still have today. During the years, don't know how it came, all of a sudden, I find 7 Baby Bee's and some Tee Dee's in the engine cabinet. And, how this comes, I even also don't know, there is a little Biplane luring around, no engine, no RC, but everytime I am in the workshop, this thing is wheeping and begging for getting in the air. Zaunkönig, some call it unflyable, some call it Adrenalin. As, in my age, even after some years FAI pylon racing, I thought, this PeeWee would be a perfect match. I managed to get this thing into the air. Not too fast, but ok for leisure flying. But, bad luck during a stupid throw by me, it hit the frozen ground. Crankshaft broke. Too bad, too bad. Lucky me, I found the last bottom end at coxengines.ca and its on the way. I have another PeeWee, but do not want to risk it. Decision made, go for a Baby Bee. I grabbed one from the drawer, put it in the plane, voila, tzzzz, the Baby Bee turned a 5x3 12700rpm. It was not enough to get the plane reliably into the air. Then I decided to start some educational test runs. I dismantled and cleaned all of the remaining Bee's. Checked the piston/liner fit of all of them. some are pretty good, some a more sloppy. Today I tested their performance using a COX 5x3, which I think is a not too heavy prop. So far only three, fingers are getting too cold quickly.

Fuel 20% Castor 30% Nitro, 50% Methanol

Bee #1   14300,    TD head 15100   two slit exhaust slot,  two transfer ports, no boosters
Bee #2  14400,    TD head  14650   old style exhaust slot, 1 transfer port, cylinder marked "2"
Bee #3  13000,    TD head, it was getting too dark for the tach,  two slit exhaust slot, 2 transfer ports, no boosters

Big surprise, the #3 Bee has the "best" piston/liner fit, #2 is on the loose side,  and '1 is also feeling good.

Question, should the piston/liner fit be more on the easy side or do the engine suffer in a too tight eg, good plopp?
#3, there is no sticking, a good plopp. All 2 liners are not "perfect located" for the transfer ports on the crankcase. Does this makes a big difference?

I always used the same Tank to eliminate a maybe tired reed valve.
Has one some rpm figures for the Bee's with a 5x3?
Is the 5x3 ok to use or a better advise?

regards and thank you for your help
Roland

Ok Roland, your query inspires me to relate an old story regarding the Pee Wee 0.020 an engine I find simply adorable. When my first Pee Wee crashed, the crankshaft broke right at the splined connection. Engine otherwise runable but seemingly dead. I disassembled the engine, shortened the crankcase with a file, crudely ground a taper on the end of the broken crankshaft and created an inside taper on the drive washer using a countersink. I put the engine back together and to my amazement it ran! So I installed it onto a simple profile free flight called a Berkeley "Baby Yank" and set off to fly it. Normally I would use 0.4cc of fuel to get a 30-40 second engine run, but this time I filled the tank, started the engine and launched the plane. The engine was running poorly and I figured it would quit. No such luck! The little gem cleared it's throat and sailed off into the sky. By now, the wind had picked up and the last I saw of it it was headed off to Valhalla. I searched through the farmer's pastures for the longest time but the airplane is still out there somewhere with my phone number penciled into the fuselage. That event was in 1971!

So you might try my "repair" and save your good Pee Wee for a more controlled environment.