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Post  DaveyMo Mon Aug 28, 2023 1:10 pm

Hello All:

I've had some poor luck getting good runs first on a Medalion 049, and now on a Golden Bee 049 (both used engines). Each featured two-port cylinders (#1 and #5), which (I think) were not standard equipment on these motors. In principle and generally speaking, should these two-port cylinders be compatible these motors? I can understand maybe a bit more power and higher fuel consumption, but inability to get good needle settings?

Maybe just bad luck on my part. If these turn out to be compatible, I'll look into other factors contributing to the lousy runs.

Thanks!

Dave Mo...

PS: By the way and for what it's worth, I managed good runs on the Medallion by re-installing the single-port cylinder.
D...
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Post  balogh Mon Aug 28, 2023 2:41 pm

Dave, I assume you swapped the cylinders together with the pistons, not just the cylinders? While COX pistons and cylinders were made for very high precision thus allowing cylinders swapping without their pistons, the most advisable is that cylinders AND their own pistons be transfered together from engine to engine. Otherwise compression loss or, tight cylinder to piston fit may occur that both will rob performance.

Otherwise single and double bypass ported cylinders are all applicable to all 049 reedies and rotary valve Medallions or TeeDee-s..of course it does not make too much sense to run a TeeDee on a lower performance No2 single ported cylinder, even if it works...

All no 1 and 4, and 5 cylinders are SPI ported, so if a muffler is added to these, the engine will loose many 100-s of rpm. (I am not sure if you use mufflers, just mention their power robbing effect on SPI cylinders.)

Good needle setting may be hampered by unwanted air ingress into to carb along the needle thread, that can be remedied by pulling a small piece if silicon fuel tube on tge valve such that it covers the needle entry into the threaded spraybar...but you said with the stock cylinders needle setting was OK so the reason may be what I hinted above, or similar..
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Post  DaveyMo Tue Aug 29, 2023 3:18 pm

Balogh
You’ve provided just what I wanted though not a direct solution to my problem. I’ll get this figured out yet. So, many thanks are owed for your taking the time to respond.
All the best…
Dave Mo
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Post  balogh Tue Aug 29, 2023 5:22 pm

No sweat Dave, I enjoy engine discussions and sharing experience...what was your takeaway from my guesswork?
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Post  GallopingGhostler Tue Aug 29, 2023 7:28 pm

@DaveyMo , I am being more speculative, but the Medallion is considered the poor man's Tee Dee. It has excellent suction feed. I saw @Cribbs74 running his hopped up Medallion .049 on bladder pressure, was able to fly the pattern on his C/L Baby Clown (same wing area as Ringmaster Junior). But, may be the forced feeding help to put more fuel down its throat so it could breath more efficiently with the greater intake bypass capacity of hotter porting like your #1 and #5 cylinders with subport induction.

I think that for others to help, they need to know more details on the exacting environment that these engines have attempted to operate on but failed. (i.e., shimming of glow head, type of glow head, exact mix of the fuel you are using, test setup, tank height, length of fuel line, height of tank with respect to venturi needle, etc.)

IMO, there is no rocket science, and once you discover the factors causing your starting problems, can be on the way to having your engines run successfully.

Got on the back burner a Medallion .049 conversion to muffling by replacing the single bypass port cylinder and SPI piston with a R/C Bee NOS non-SPI dual bypass and exhaust throttle muffler (same with silicon rubber cover. So, when I do, don't anticipate problems, but will know more when I get there. (Just got too many irons in the fire, now.)
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Post  DaveyMo Wed Aug 30, 2023 8:24 pm

Hello

My takeaway from Balogh’s follow up is that poor fuel might be the problem. Most other bases have been covered. Tried the go juice on three motors and no luck at decent runs or even good starting. The motors were two Golden Bee’s and a Wen Mac 049.

Will get a new batch of fuel, give it the ol’ college try and then report back here. At that point if things are still in the doldrums, I’ll take GG’s advice and lay out the particulars on these three mills. GG: the 049 Medallion is one fine motor in my book!

Much obliged, good brethren.

Dave Mo…

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Post  DaveyMo Thu Aug 31, 2023 11:03 pm

Hello again:

Had good success with one of the double-ported Golden Bees. I tried new fuel and an electric starter. Of the two variables, I really think the problem was in trying to hand start the beast. Even with the electric starter I had to figure out a routine that worked. Will try the older fuel tomorrow after my nerves settle down. The successful run was with a full tank on a very tail-heavy Baby Flite Streak. Oh, was that interesting!

Thanks all. I'll be back with reports on the other two mills.

Dave Mo...

PS: My electric starter is a little homemade job fashioned from a Dust Buster motor and PVC pipe. It actually works.

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Post  balogh Thu Aug 31, 2023 11:38 pm

Good to hear you finally managed it with an electric starter. (Is the compression of the engine OK?)

In order to prevent excessive wear of the crankcase nose when cranked with a starter, a steel or phenol washer is placed between the prop drive plate and the nose. I am not sure if the Golden Bee has that or not. Also, an overprimed engine is prone to hydraulic lock and this may damage the piston conrod or break the crank pin, if forced by a starter.

I therefore add the washer for engines that I start with electric starters, and bump the starter then release the start button before the cone touches the prop spinner, and the engine is cranked by the inertia of starter rotor only. Safer than starting with current running constantly through the starter.
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Post  getback Fri Sep 01, 2023 7:26 am

Don't know if you know this but we have instruction / start procedure manuals where it says INFO >   https://www.coxengineforum.com/h24-instruction-sheets   Trouble shooting > https://drive.google.com/file/d/1iNo75W7RzPkE4QDKCHwa1ixYhbhjiYSq/view  Just saying everybody here will help though it may take time and there is alot of good stuff in there too . Very Happy
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Post  DaveyMo Fri Sep 01, 2023 1:20 pm

Balogh:

Yes, the motor's compression is very good. I don't intend to rely on the electric starter as I hope to learn the best routine for hand starting (don't want to damage the engine). I'll be careful to avoid hydraulic lock as I saw what it did to a connecting rod in a Norvel at the AMA event in Oshkosh a few weeks ago. Thanks.

Getback:

Hey, that is a great collection of info sheets! Thanks for mentioning it, and many thanks to whomever did the work on getting them into format.

Dave Mo...
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