The quote below has been posted a number of times. I will preface it by saying that I have NEVER experienced a failure in any of my 4S engines that I’ve treated as described below. I have had only one engine degrade in performance – that being an OS Surpass .40 that I bought used. I replaced the bearings and one valve. 

After the lube as below, my standard procedure is to run a new engine for at least one hour, using 5%, 22%, 50/50 fuel. When it runs steadily and there is no dark discharge from the breather, I run it for another half hour and then check/adjust the valves. When I put it in a plane, I use Brodak 10%, 23% 50/50 fuel. This is the fuel that I now use in ALL my 4S and 2S glow engines.   

I now have the following 4S engines in planes and flyable: 2 OS .20s, 3 Surpass .26s, 3 SAITO .30s, 1 OS .40, 1 Surpass .40, 1 SAITO .40A, 1 SAITO .50, 1 ENYA .53 and 1 SAITO .56. All run perfectly and none, except the Surpass .40, have ever been disassembled. After the initial setting, I have never re-adjusted the valves. Most, if not all, are still running with the original glow plug. 

My quote: “On a 4S engine, the crankcase is vented to atmosphere - an intentionally planned leak. Remember, our engines have no lubrication sump per se. Instead, ALL lubrication is derived from the residual fluid (mostly oil) that passes the ring(s), AKA blow-by.

If you look at the older 4S engines, most of them had the breather nipple in the backplate. The newer and more powerful variants have the nipple in front of the rear bearing or on the camshaft housing. This insures that any flow of lubricant exiting the case must first pass by the bearing. It will also get into the cam drive gears and be flung around to the remainder of the valve gear.

Here's a trick I use - whenever I buy a 4S engine, new or used, I remove the valve cover(s) and check valve clearance. I have seen new ones with none. Better a bit on the loose side for run-in.
 
Then, I flood the valve gear with oil. I also squirt a teaspoonful into the breather nipple and wrap a rag around it to catch the oil. Flipping the prop a few times insures that all is wet inside. When I start it, the excess just burbles out.

After flying, I normally inject some lube into the breather and flip the prop a few times.

By the way, I use Winsor Lube, type L-245-X.” 

For what it’s worth. I attribute my many hours of pleasant and successful 4S flying to proper break in, quality lubrication and realization of the engines operating limitations.

And, of course, to quote the often-used caveat: “Individual results may vary” 

Bob Z.

Bob I also like 4 strokes I have a O S 48  surpass and a os 20 fs , Y S 91 I found that Powermaster works , and on the 48 I left the throttle on so I start it with idle to let it warm up the valves , and never had a lose prop. just run them on the rich side with a good prop load (pitch)

Dennis - WRONG INFO. 

Yes, I bought a brand new SAITO .30 and during break-in, I noticed that the black breather discharge did not subside as it should.
I also noticed that the valves needed more adjustment than usual.
I set the valves and decided on a test flight anyhow - the clearance opened up by .005 in one flight. 
Sent it back to Horizon for warranty fix. Sent it ONCE, not twice.
When it came back, it did the SAME THING. 
I sent it back, REQUESTING, NOT DEMANDING a new engine, not a refund.
Exercising their excellent customer service, they complies with my request. 
I ran in the new engine  and it is now living happily in the Argus and runs as close to perfect as I could expect.
I now have three SAITO .30s flying, in the Nobler, the Little Cherokee and the Argus. All are  running as well as I could possibly hope for. They are my favorites.
At the GSCB swap meet, I bought another new .30.
The one defective SAITO I had will in no way sour me one them - they are still my all-time favorites.

Larry - I have no experience with the YS as I'm tending to stick with the smaller engines, probably just the .26 and .30. I believe Doug or Steve Moon tried the YS.

I have a few Surpass .48s and the few times I used them, it was quite impressive. They were discontinued in favor of the .52.

I was using Powermaster exclusively, both the 10/22 and the 20/20. I have now switched to Brodak 10/23 and I will modify my OS .40 4S to use it also (It presently runs best with 20/20).

Cougar and anyone else who wants Winsor lube - I have 5 gallons of it and I will send some to anyone who wants it - for FREE - all you do is pay postage.

Bob Z.

Bob,

That sounds like an engine failure to me. Certainly a specific engine you did not want to run.

As for Philly Flyers ( Bob Zabelli's club), a club I've been a member of for the last four years. This is some of the experiences we've had with Saito 4 strokes.

Three Saito 72s have been put in serious stunt planes, flown by well known Expert flyers. Two of those engines experienced conrod bearing failure early in the flying/trimming stage. Guys long familiar with model airplane engine dynamics, not in the least ham fisted or abusers of things mechanical. One fellow thinks the runs in his engine were overlean even though they sounded o.k., this causing the failure. I haven't checked with the second fellow. Both engines were repaired under warrantee. As far as I know  the engines are presently not used much. In any case, no four stroke Saitos in their comp planes at the moment.

The latest Saito 72 destroyed it's valve gear and froze in a new beautiful stunter flown by a well known top 20 flyer. The airplane was saved by some skilled moves. The engine was rebuilt by Horizon who did not replace an obviously compromised pinion gear. The flyer purchased the gear and replaced it. The failure occurred after less than 100 flights. It's thought that a combination of RC fuel with insufficient oil content(fuel recommended for 4 stroke engines by a knowledgeable RC flyer) and an unusually tight ring/piston/cylinder fit oil starved the valve train. The rebuilt engine is currently flying delivering good power characteristics. As a side note, in order to make the Saito work, custom venturi's were machined and used replacing the carb.

As for Saito 40s. One club member after weeks of attempts to gain consistent usable runs, sold the engine on ebay. Another member has two Saito 40s one goes screech screech as it's turned over. Not usable. The other seems to work o.k. At times he competes with it.

I've seen Saito 40s cut out in maneuvers at odd times, trashing planes. Well, so have lots of 2 strokes.

But perhaps the most telling evidence of our experience is the number of four strokes that regularly show up at our field. None, outside of Bob and our top 20 flyer. The top 20 flyer is dogged, skilled and intuitively in sync with our tiny internal combustion engines. Despite his Saito 72 failure, he flies it and pushes on. Probably evolving his system into a viable competition stunt combo. It was not easy or straightforward.

Originally, when I mentioned four strokes on this forum, my point was that some have given these engines a free pass, extolling their virtues, without providing critical information about their special needs and shortcomings. Almost everything in this thread supports my point of view.

Best,

Dennis Moritz

Hi, Dennis - I should have clarified a bit more. 

The engine that I plan to modify is the non-surpass .40. It has a low compression ratio and runs perfectly on 20/20 Powermaster fuel with 2% castor added. I plan to remove the head shim and lap the head to the sleeve in order to raise the compression ratio. My rationale is to be able to use the same fuel - Brodak 10/23 in all my engines.

Regarding your purchase of the Surpass .40 - as far as I'm concerned, it one of the most, if not the most powerful .40 available. I have been running mine for the last three years on Powermaster 5/22 fuel. Per my stated rationale, that is, using the same fuel in all my glow engines, I might just go the other way with the Surpass .40. I will lower the compression.
Why?
Because with 10% nitro, it's just too much. I want to tame it down a bit. By adding a head shim, I can reduce the compression and run 10% nitro.

Here's what I suggest for yours: Pre-lube it as I've described above in my October 3rd post.
Following the manufactures instructions, run it in on the recommended fuel.

After you've run it for about an hour, check the valve adjustment and then try it on a plane. Try the 5% nitro/22% oil. Remember, NO LESS THAN 20% oil - EVER!!!!
If you're pleased, do nothing more - just keep flying it.

AND, keep this in mind: When you change the compression ratio by moving the head, you MUST re-adjust the valves.

Finally, I suggest that you stay away from low-pitch props. Most of my engines are happiest with 6 to 7 pitch.

Have fun and, if you want to be on my 4-stroke info exchange, let me know. 

<rzambelli@moog.com>

Bob Z.

...
I have been flying 4S engines longer than most people and when queried about lubricant, I always said "20% minimum, and try for some castor in the blend".
...
I don't know what you mean by a "free pass" but unless an engine, ANY ENGINE, is properly treated, all bets are off.
...
I follow the directions written and approved by the engineers who designed the 4S engines. That's why mine work and will continue to work for me.
...
Main point here, as with anything - follow the directions. The engineers who designed these engines know what they're taliking about.
...
Bob Z.

This is excellent advice. Sorry for the cuts, but these are the points that ring out to me. As a beginner, I've gotten lots of advice from experienced fliers who assume that their experience in one specific area carries over into expertise in a broad area. Case in point, I have an OS Max 35S, customized by a well known builder who recommends 25% ALL CASTOR LUBE fuel, so that's what I run (actually, I run 29%). Every single time I show up at the field with this plane, I'm told the engine won't run correctly with that much lube (especially all castor), I can get by just fine with 18 or 20 all synthetic, etc... sometimes I'm reminded of how much experience they have running model engines... but all of their experience is with modern AAC/ABC/ABN engines. They know so much they don't need to read the directions:) Some of them even know more about the engine than the company or person that built it:) This is not meant as a slam on anyone, just an observation of human nature.

cheers,
Ken

Look, folks, these guys who ran the Saito 72s have been flying a heck of a long time and have been quite successful competitively. You'd know who they are if I named names. All of these caveats and cautions that Bob's in high dugeon about. Think these guys who've competed on the highest level, people who have known Bob for many years, and run all kinds of engines even designed engines presently in production, think they didn't read the directions in the package or talked to people about Saitos. Gimme a break. Suddenly there's a lot of cautions talked about etc. Among them limiting the revs of Saito 72s to 9000 rpm etc, running a little castor. Etc. Etc. 23% oil. Put this special lube up the spount after running. Well, until I raised the issue of Saito durability when run as a SERIOUS stunt engine, none of these extra cautions where out there in the forums. As far as I can tell Saito doesn't mention any of this in their literature. Why would they. They don't manufacture any purpose built control line engines. They manufacture only RC engines. Different environment.

Also, the gentleman who have run the Saito 40s and experienced breakage and inconsistent running were not new flyers by any means. They compete and have many many years of experience.

As far as the European run Saitos I believe Berringer modifies his engines. We don't know what these guys do by way of maintenance and how hard they run their engines. We don't know their learning curve. Sure, they've figured out how to make them work and last. Think they figured it out by reading Saito literature. Trial and error. Back in the day guys raced flat head Fords. If you have looked at almost any part in a Flat Head Ford, you'd understand the absurdity or discipline. But they ran. People figured out how to keep the bucket of bolts from blowing up. Definitely not easy.

My point, among others, is that the Saito engines need to be run within certain parameters in order to maintain durability in competition stunt control line. And that these parameters were not widely known or publicized.

Also, as far as competition stunt on the highest level, the preference in the USA is obvious. Purpose built 2 stroke power, largely PAs and Ro-Jetts. When Richard Oliver shows you a 90 and says he's run 12 gallons of fuel through it (six ounces per pattern) and you watch and hear this engine pull a stunter...  When I look at a PA 61 that I know has been flown hard in competition for five years... well, different ball game.

Sport engines don't get run any way nearly as hard. Forget about it. Presently I've got eight or more flyable planes that I take out and spin around. Probably typical of sport flyers. Flying once a week or less maybe eight months a year, doubt that any of the planes gets more than fifty flights a season.

Four Strokes have some desirable power characteristics. Definitely. I've seen them work well pulling at what appears to be a constant speed up and down hill. But...

Do we have what amounts to $180-$220 sport engines that need to be modified for serious competition and run within certain paramters to work on the highest level. O.K. well that's what they are.

Best to all,

Dennis Moritz

Right now a Saito 40a is the best running most consistant engine in my fleet. Took me two weeks of trial, error and listening to advise from others to get it there but I was determined.

You sure can't apply anything you might know about 2 strokes and think that's why many have been less than successful trying to run a 4 stroke. The info is out there just some (like me in the beginning) didn't/won't listen.