Bikerboy53

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Hey all,

Question in regards to proper fuel mixtures, I've heard a lot of the guys at the field where I fly say that they generally use a 30:1 fuel mixture for all of their gassers new or not, is this a safe idea in terms of break-in ??

Thanks in advance

Biker

Propworn

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What does the manufacturer recommend????? Why would you not follow that?

Dennis

Bikerboy53

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Im fully aware of what the manufacturers reccommendations are, I was just curious.....

Biker

RCFlyerDan

My Feedback: (54)

I use Amsoil 100:1 and yes, I use it that way for break in too. It works on the quality engines, but not so much if you buy one of the cheaper Alphabet engines. I've used this fuel mixture for DA, Zenoah, and Saito. Break in is more about having a rich needle valve setting.

ahicks

My Feedback: (2)

20cc and up you're fine at 32:1. In fact, many have spent time recently proving there is nothing to be gained by running less in any RC engine. You're not going to make any more power, and you aren't going to make the engine last any longer. This raises the question of why would you want to run any less than 32:1.

When you drop down below 20cc, they're so small they drink very little fuel. I think it best to do what the manf. says to do.

BarracudaHockey

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An entertaining debate that crops up about once a month. I run Red Line 40:1 in everything from my 8cc Mustang to my 120cc stuff and my weed wacker and blower.

RCFlyerDan

My Feedback: (54)

Entertaining Andy? LOL>>> I wasn't trying to start a contest, but just showing the extremes that are currently used in the hobby. The only reason that I started with Amsoil was due to buying a new engine from DA. At the time they recommended, but I think have changed to Red Line. And, I have 3 new quarts sitting on the shelf. In truth, you can't go wrong with 32:1 in any engine. Some are more sensitive than others. Gas engines are also normally "broken in" flying, and not running on the ground. Just run rich, but not so rich that it is coughing, fly high and always have a plan for a dead stick. Gas engines don't start to break in for a couple gallons.

av8tor1977

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Well, everyone has an opinion on these things; some quite strong ones.

I like Pennzoil for Air Cooled Engines for the first gallon or so, then either Redline Racing or Stihl Ultra HP oil. 32:1 ratio for everything. Ya can't go wrong with this combo. I have a Super Tiger .90 converted to run on gas, including updated to roller rod bearings. It might be ok at 32:1 synthetic oil, or some would say even less, but I run that one at 20:1 just to be safe. There is absolutely nothing to be gained from using less oil. Compression is actually better with more oil.

And I only run a gasoline engine on the rich side for the very first tank of fuel. After that I tune them normally, and fly them at varying loads to heat cycle the engine. A gas engine does not need to be run real rich for break in like some glow engines, and it's actually not good for them.

AV8TOR

Bikerboy53

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All of this makes good sense, I was just curious in terms of whther or not I could get away,with a "one size fits all" mixture...

Thanks all for your valuable input ����

Biker

BarracudaHockey

My Feedback: (11)

Short answer, yes.

I love all the debate about this but think about it, what do 99% of people do with their lawn equipment? Fuel it up, start em up and run them all summer wide open.

ahicks

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Yup, and there are hundreds of those for every RC gas engine in use! I think you might be running your baby gasser on the ragged edge, but I'm one of those that burnt a crank pin with the 10, so I may be running with a little more caution (20:1). -Al

av8tor1977

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On the face of it, this makes sense. However, when you look a little deeper, it is not an "apples to apples" comparison. The gas engine lawn equipment is designed to be "idiot proof", durable, and nearly "bullet proof". As such, they are de-tuned by having small carburetors, low compression ratios, and conservative port and ignition timing. They are also provided with very efficient cooling systems. As such, they can survive with rough and poor treatment much better than our airplane engines. And what happens if one blows up? You just go back to watching the ball game, and buy a new one next week....

AV8TOR

ahicks

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That pretty much describes the engines I"m thinking of when thinking RC. For example, look at the exhausts we're running. For the most part, our engines are just not all that sophisticated at all. They can't be. Not if they're going to be inexpensive and friendly handling. More refined are going to require MUCH more sophistication. Like exhaust valves, tuned exhaust, and MUCH more sophisticated carbs.

As far as cooling, agreed there are few variables with fan cooling, but the truth is, the cooling systems required to make our favorite engines live a long happy life don't need to be all that efficient. Not until you get into the bigger stuff anyway. My thought, FWIW, -Al

AA5BY

My thinking on what happened to the 10cc was a result of combining needle bearings with ABC piston/sleeve. My explanation of why that can be a problem is that a needle bearing suffers some degree of scuff time of two hardened steel surfaces because the needle roll distance is dissimilar between the crank pin and bearing race. Normally that scuff time is protected by oil film that keeps those surfaces apart... but the tight fit near the top of the tapered sleeve causes too much pressure between the needles and crank pin and especially if the engine is broke in or run in cold weather or with a too rich mixture..

av8tor1977

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See post #3 here:

http://www.rcuniverse.com/forum/engi...e-project.html

AV8TOR

AA5BY

Yep... we are on the same page.

Horizon Hobby did a great job of repairing all the damaged crank pins on the Evolution 10GX, but they blamed the problem on some poorly hardened crank pins. I'm not convinced that was the problem as I think it had to do with ABC and needle bearings. Mostly I think it had to do with breaking the engines in during cold weather.

ahicks

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I know we're off topic here, but-
Cold weather theory won't work here. Mine was done during summer months - and I was pretty careful with it.

I don't know if the 8cc engine is ringed or not, but if it is, I guess I could finally see the reason they brought that out when they already had the 10cc engine.....

AA5BY

Machining tolerances are always in play. The cold weather wasn't intended to be a hard requirement but rather a point that tightness was more the cause than crank pin hardening. If crank pin hardening had been the issue, it seems to me that all early production would have suffered the problem.

I've not heard of a single 15cc with the problem. It is not an ABC engine.

Bikerboy53

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So, what if one had some fuel in a container that was mixed at 30:1, but its been in that same container for over a year, would it still be alright to use that?

speedracerntrixie

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Typically I would not use gas that is more then a month old but I may be a bit over cautious then others. As far as gas/oil ratios are concerned, I would not hesitate to use 30:1 in engines 20cc to 80cc 40:1 in engines 80cc and up. For the record, my DA 150 spent most of its life on 40:1 and multiple brands. For engines smaller then 20cc, follow manufacturers specific instructions.

ahicks

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Good oil (even just decent oil) has a stabilizer in it that will extend the shelf life well beyond a year. It's the gas that's not mixed with anything that I would be nervous about after sitting that long.

av8tor1977

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+1 for sure for me on the one month. In the Rotax Authorized Training Course, they teach that "Gasoline starts going bad from the moment you put oil in it." They should know. It wasn't any news to me. In motorcycles and Ultralight airplanes, my limit is two weeks on mixed fuel. For the smaller, model airplane engines I will sometimes go as long as a month, but even that bothers me a bit. Really, it is best to make up new fresh fuel for each flying session. What's 3 bucks as compared to the price of your engine, AND your plane??

Oh boy, the "fur will fly" now!! I'm outta here!!

AV8TOR

ahicks

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So to reinforce my earlier comment about checking to see if they'll run prior to rebuilding the carb or anything else, I just pulled an old 26cc RCGF/Aerovate off the shelf that has not been touched since 2010. It was being flown quite a bit, but the plane crashed, the engine was pulled and set on the shelf, and hasn't been touched since.

I just put it in a new plane and have it completed to the point it was time to see about getting the engine running. I pulled the singe screw cover off the carb, gave it a squirt of fuel to wet everything down, and reassembled. With the choke closed it started for a second and quit on the first flip. Choke open, and 2 flips later it was idling, having pulled fuel all the way from the tank on an all brand new fuel system. Gave it a second to warm and distribute fresh oil internally, and it runs just like it did when i parked it. Maiden in the next few days.

You mileage may vary.....

kmtranmd

My Feedback: (71)

Many of us at local field run Redline 50:1 for new and old, to avoid messing w needles.
key to break in is avoiding sustained wide open runs to avoid overheat, not need to richen it and end up w carbon build up.
i do avoid running gas more than 4 mos old, will not idle well. I had no problems running gas 2-3 mos old.
i do try to buy quality Chevron gas instead of Arco gas given small price difference.

av8tor1977

My Feedback: (6)

Yeah. I wouldn't run ARCO in even a lawn mower. Very poor gas.

AV8TOR