Cylinder devarnishing -again

Hi All,
Clarence Lee said use hot water and dishwasher detergent.
Rince with fresh water, dry it well, oil, put it back together.
Works for me.
I have a loving relationship with my varnished Cox pistons/cylinders.
Your results may vary.
Take care,
Have fun,
Dave

Lots of ways here. I use red Scotchbrite and either carb cleaner, acetone or lacquer thinner. Whichever is closest to my chair. Usually carb cleaner because it has a handy spray nozzle. Sometimes I don't even disassemble the bigger motors like .15s and up where a finger fits in. Just scrub the cylinder upside down to keep fuzz and dirt out. Head off of course. Scotchbrite does not remove material unless you try real hard. Foxes are a different animal. They wear so bad that they only survive with lots of oil and varnish, but work OK anyway.

I ran Maxima Castor 927 in a diesel for quite a bit and the combustion chamber was very clean. Even if you didn't want to run 927 continuously, I bet it would clean a cylinder pretty quick. It's known to run very clean.

https://maximausa.com/series-252-castor-927.html?locale=en

It is interesting to listen to the ways things have changed over time to care for our little glow gems of engines. I'm guessing that the reason why Leroy Cox included 2% synthetic oil with 18% pure Casor was to keep excessive varnishing at bay. 50 years ago, I was buying what ever was available at the local hobby stores on military bases, which could be a combination of Duke's fuel (Fox), K&B Supersonic, Testors half-A, which were more common than Cox.

In late 1970's, then SIG 25% Champion all Castor seemed the best priced all around fuel at the local hobby stores (all base hobby stores were closed by then in Hawaii, victim of cheaper mail order prices.) My little 1965 OS Max .10R/C ran fine on the half-A fuel. Looking back, I guess I was a peddle-to-the-metal - metaphor for a car's gas pedal pushed to the floor) person with these half-A and A engines.

I always shot for the higher nitro content fuel above 15%, because I found that the little Cox .020 Pee Wee and .049 reed valves seemed to love the higher nitro stuff. I was replacing glow heads regularly. (After some running, the wire element would look like ash, I guess a combination of wear and tear by high nitro fuel.) But, de-varnishing became a ritual after a couple weeks flying, when I noticed RPM's were not up to snuff.

With experiences to what is best changing over time, I see now why it has been refined to 10% Synthetic with 10% Castor as the best overall formulation. This gives one more time between de-varnishing exercises.

GallopingGhostler wrote:It is interesting to listen to the ways things have changed over time to care for our little glow gems of engines. I'm guessing that the reason why Leroy Cox included 2% synthetic oil with 18% pure Casor was to keep excessive varnishing at bay. 50 years ago, I was buying what ever was available at the local hobby stores on military bases, which could be a combination of Duke's fuel (Fox), K&B Supersonic, Testors half-A, which were more common than Cox.

In late 1970's, then SIG 25% Champion all Castor seemed the best priced all around fuel at the local hobby stores (all base hobby stores were closed by then in Hawaii, victim of cheaper mail order prices.) My little 1965 OS Max .10R/C ran fine on the half-A fuel. Looking back, I guess I was a peddle-to-the-metal - metaphor for a car's gas pedal pushed to the floor) person with these half-A and A engines.

I always shot for the higher nitro content fuel above 15%, because I found that the little Cox .020 Pee Wee and .049 reed valves seemed to love the higher nitro stuff. I was replacing glow heads regularly. (After some running, the wire element would look like ash, I guess a combination of wear and tear by high nitro fuel.) But, de-varnishing became a ritual after a couple weeks flying, when I noticed RPM's were not up to snuff.

With experiences to what is best changing over time, I see now why it has been refined to 10% Synthetic with 10% Castor as the best overall formulation. This gives one more time between de-varnishing exercises.

I hate to go onto the castor oil conversation because of the strong feelings over it. But. We just used 2 to 5% castor and total of 20% oil many years ago. The castor was only added in just in case the rumours were true, which I doubt, but in control line sometimes a lean run at the end of a flight may need some extra protection. Maybe Greg's oil that he found might be a better solution than even synth. I won't be getting any for the price point only. $28 a litre U.S. works out to about $50 Canadian after shipping and the 37% premium. I can just buy another motor after running a couple gallons through of that oil. Around here-in Detroit there is supposed to be a cheap place to get castor, but I have not been able to cross the border since the plague and now I guess I need a passport.

I didn't find this oil. It's been around since 1979 and was the companies first product. Some F2C racers have sworn by it for decades. You could probably also run less 927 than plain castor or castor/synth.

Check your local motorcycle shop. Virtually all use a distributor which handles Maxima. Just have to see if they can order it. Last time I bought locally.

I gotta' say; I've never purposefully devarnished any of my Cox engines' cylinders. As of late; I've started breaking-down a few engines and paying more attention to crankshaft/journal devarnishing.

That said; I do use a brush with spiral'd "nylon bristles".. having a 1/2" (12.7mm) diameter.. which is optimal for the .049/.051 Cox cylinders. I've had this brush for a LONG time.. so I'm not sure where it came from. Either "Grainger" or "McMaster-Carr".. most likely.







This is a "stiff-bristled" Nylon brush.. and will scrub the cylinder without scratching it.

I especially liked HalfaDave's mention of the "Clarence Lee" method earlier in the thread. This would be the perfect brush to use prior to swabbing/oiling.

I actually applied that sort-of after-washing, following a successful deburring process recommended by Ken Cook. I used that brush throughout the rinsing-process.. to be sure that no abrasive polish remained.