4-Stroke Lub?

[posthole_digger]

There is a thread on the RCU forum about the need to lubricate 4-strokes. There is a lot of strong input that the rockers and cam are shipped dry and get little or no lubrication from the fuel. They recommend oiling these part regularly.

Any comments? I know at least some of you use these engines.

Paul

[Tom Rounds]

I have used 4 strokes in R/C planes for many years. Only problems I have ever had was with valves that would not seat after several hours of flying time. Found out that this was from using a syn/caster mix fuel. Valves would get a build up on the stems that would keep them from seating. We switched to total syn. oil and the problem solved it self. I have used Saito and OS 4 strokes both. 4 strokes do need a valve adjustment from time to time. I have never had and rocker problems though. 4 strokes seem to be happy with 15% nitro also. I cant give you much advise on using them in c/l planes though.

[Scott Hartford]

Saitos are shipped nowadays with moly lube on the rockers, cam and followers. The first dreadfuly rich run at low RPM for break in will oil things plenty.

[Robert Zambelli]

Paul:

I've flown 4 stroke engines (ENYA, OS, and mostly SAITO) and would like to offer some information I've gathered over  the years.

I have a standard treatment for all the 4S engines I buy and use. If it's a used engine, I take off the backplate, plug and valve cover(s). I then flush it thoroughly with alcohol to remove any debris or lube that may have gotten inside. Blow out as much of the alcohol as possible with compressed air. After checking/setting the valve lash, drizzle oil (I use Windsor Lube Aerospace oil) over the valves and rocker arms, insuring that it flows down into the push rod tubes. Replace the valve covers. Put about a teaspoon of oil into the crankcase and replace the backplate. Cap the breather nipple and put on a prop. Turn the engine over slowly while rotating it around to insure that the oil gets to all internal parts, including the timing gears and cam.

Now, replace the plug. Insuring that the engine turns freely, mount it on a test stand. Uncap the breather and put on a long piece of tubing, as things will be messy for a few seconds of initial running. Set the needle rich and the throttle about half open and start it. After a minute or so, open it up and run it for a few minutes. Play with the throttle position and needle valve settings until you're comfortable with it. It should be ready to fly at this point.

When I set up a new engine, I use the same procedure but I do not remove the backplate or do the alcohol flush. I squirt oil into the breather nipple and insure that the inside is totally oiled. ALWAYS check the valves. I have removed valve covers on brand new engines and found not only zero clearance but the rockers totally dry. This bit of extra time spent will insure that all parts are properly lubricated during the all important initial running. Regarding throttle and needle valve settings, follow the instructions for a new engine. After run in, check the valves and you should be all set for many seasons of flying.

Fuel: For years I ran Powermaster 10/23 (50/50) in ALL my engines. Excellent fuel. I recently switched to Brodak 10/23 (50/50) also with excellent results. I have NEVER has issues with carbon accumulating on the valve stems and 10% nitro gives me adequate power for my needs. Also, the residual castor gives good protection against rust.

I have heard of people flying RC and having trouble with castor based fuel but I think it may be due to the fact that they run theirs at different throttle settings, from idle to flat out. During idle, some carbon may accumulate and not burn off. For the most part, I run mine flat out. The valves may just stay hot enough to prevent carbon deposits. Whatever, it works for me.

In closing, I should mention that most of my flying has been with the smaller engines - the .20, .26, .30 and .40 sizes. I have tested and tinkered with lager sizes up to the .91 but not enough to offer much helpful assistance. Many people on this sight can offer assistance with the "big blocks". Mr Moon, Mr Walker and Mr Graham probably have the most experience.

Hope this helps.

Bob Z.