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ORIGINAL: Mr Cox

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ORIGINAL: GallopingGhostler Speak of OS carbs, my OS Max .10 RC baffle piston engine has no idle air bleed adjust screw, yet it idles fine as though it doesn't need it.

It has an airbleed, or a similar low end compensation, it is just that it is not adjustable. Other engines like that are the Norvels and MP Jet (plain bearing one).

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Engine Review O.S. Max 10 R/C by Peter Chinn The carburetor fitted to the Max 10 R/C is a smaller, simplified version of those currently used on the larger O.S. R/C engines. It employs a diecast and machined aluminum body with ground brass throttle barrel and, feeding into the center of the barrel, a jet that is adjustable so that choke area may be varied for more suction or, alternatively, for more power. The needle-valve and tee-fitting fuel inlet are both on the left-hand side of the engine and do not interfere in any way with the movement of the throttle control which is on the opposite side. The needle-valve and jet assembly are screwed into the solid end of the carburetor body, unlike the fitting on some other O.S. carburetors in which the assembly was mounted in a separate pressed-in dural plug - a feature that has been found to be somewhat vulnerable to crash damage.

The main difference between the Max 10 carburetor and the larger O.S. throttle carburetors, is in the absence of both idle stop screw and airbleed screw. The absence of an idle stop means that the idling position of the throttle barrel has to be established by servo linkage adjustment or by adjusting the position of the throttle arm (held by a single screw) on the throttle barrel. The lack of an air-bleed, or other means of adjusting idling mixture strength, however, does not appear to be a disadvantage on this particular engine since it idles as well as most other engines with air bleeds.

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ORIGINAL: GLGofLB

Stay away from MECOA  =  PU

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ORIGINAL: GallopingGhostler

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ORIGINAL: Mr Cox

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ORIGINAL: GallopingGhostler Speak of OS carbs, my OS Max .10 RC baffle piston engine has no idle air bleed adjust screw, yet it idles fine as though it doesn't need it.

It has an airbleed, or a similar low end compensation, it is just that it is not adjustable. Other engines like that are the Norvels and MP Jet (plain bearing one).

According to: http://sceptreflight.net/Model%20Engine%20Tests/OS%20Max%2010%20(1966).html

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Engine Review O.S. Max 10 R/C by Peter Chinn The carburetor fitted to the Max 10 R/C is a smaller, simplified version of those currently used on the larger O.S. R/C engines. It employs a diecast and machined aluminum body with ground brass throttle barrel and, feeding into the center of the barrel, a jet that is adjustable so that choke area may be varied for more suction or, alternatively, for more power. The needle-valve and tee-fitting fuel inlet are both on the left-hand side of the engine and do not interfere in any way with the movement of the throttle control which is on the opposite side. The needle-valve and jet assembly are screwed into the solid end of the carburetor body, unlike the fitting on some other O.S. carburetors in which the assembly was mounted in a separate pressed-in dural plug - a feature that has been found to be somewhat vulnerable to crash damage.

The main difference between the Max 10 carburetor and the larger O.S. throttle carburetors, is in the absence of both idle stop screw and airbleed screw. The absence of an idle stop means that the idling position of the throttle barrel has to be established by servo linkage adjustment or by adjusting the position of the throttle arm (held by a single screw) on the throttle barrel. The lack of an air-bleed, or other means of adjusting idling mixture strength, however, does not appear to be a disadvantage on this particular engine since it idles as well as most other engines with air bleeds.

Mine differs from Peter's in that mine has an idle adjustment screw. Regarding idle mixture, the only means of compensation is to adjust the needle valve jet in or out. Upon disassembly, there are no compensating circuits of any kind.

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ORIGINAL: lopflyers

Moki, stay away from those. Real PITA.

Saito & OS are the real winners

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ORIGINAL: Mr Cox Again, it does have a compensation but it is not adjustable. The orifice above and below the throttle barrel will not close off at the same time. There are several ways to achieve this, one way is to offset the bore for the throttle barrel to one side (forward or aft), the lower part will then close off before the upper part. This is how OS did on their .10 engines and you can easily see this if you take the carb off the engine and look from both sides at an idle setting.

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ORIGINAL: RCPAUL

If Fox engines are so good, why was there a site called Fliteline which told you how to fix all the very many problems onto many models?

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ORIGINAL: Daniel-EL

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ORIGINAL: GLGofLB

Stay away from MECOA  =  PU

I agree.

Also some of the Saito engines kick like a mule and will throw spinners/props/propnuts (even double nutted) regularly. I sold my Saito 80 and one of my Saito 150s for those very reasons. Of course, there was a market for them since some guys love them regardless, and are able to tame those negative characteristics somehow.

My Saito 90 and 130TD, on the other hand, are marvelous engines, run perfectly, and pose no threat to my teeth.

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ORIGINAL: GallopingGhostler

Regardless, it works, and works well. The engine is one of the most easiest starting and reliably running engines I've used. It idles reliably and transition to full power is smooth. How they accomplish this matters little to me. The engine has a lot of torque, is a good way to hop up a margin half-A to sparkling performance. That is most important.

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ORIGINAL: aspeed I'll still stick with my story that most engines made in the last 5 to 10 years are pretty good, with only normal quirks. Using a matched motor to your plane and skills being taken into account.  Like a Jett being a great motor, doesn't go on a trainer, and an OS LA .46 doesn't go on a pylon racer.  They are both fine motors though.

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The stuff from the 1950's and 1960's was developmental really and shouldn't be used to judge a modern CNC made motor. The Cox stuff was made very accurately for the time and was a very good design, as were the Foxes (they had some weird ideas)  but that was a long time ago and things change.

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Never owned one, but I thought the fix was to use 0% nitro fuel?

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ORIGINAL: jeffie8696

I wondered how long it would take to turn into a slugfest.

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ORIGINAL: Mr Cox

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ORIGINAL: GallopingGhostler Regardless, it works, and works well. The engine is one of the most easiest starting and reliably running engines I've used. It idles reliably and transition to full power is smooth. How they accomplish this matters little to me. The engine has a lot of torque, is a good way to hop up a margin half-A to sparkling performance. That is most important.

I don't agree, there is no way that OS can know what type of fuel, nitro level, prop size and tank installation you will have. It is the same problem with Norvels and PAW engines etc too. You do need a low end-adjustment, anything else is just a compromise. On the OS .10 you can put a OS .15 carb in as these do have an adjustable airbleed. On PAW engines I've put in Enya 09 carbs (with adjustable airbleeds) and the Norvel .074 really improves with a low end adjustment too. Not offering a low end adjustment is just a way of saving some money in the manufacturing, while offering a mediocre product. Try using an inverted engine setup and you'll soon see the problem with not having a low end adjustment...

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The MAX-10R/C engine has been designed specially for single channel radio control rhodels and is notable for its easy handling, excellent throttling characteristics and light weight. It is manufactured by skilled craftsmen to strict tolerances using modern precision machinery and carefully selected top quality materials, to ensure consistent performance and long life.

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FUEL: Break-in - 70% methanol, 30% Castor oil; General - 75% methanol, 25% Castor oil; Contest - 70% methanol, 25% Castor oil, 5% nitromethane.

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Propellers Suggested propellers are 7x4, 8x3 or 8x4 but, as the suitability of the propeller varies according to size and weight of the model, make your final selection after practical experiment.

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ORIGINAL: aspeed It is a cost cutting effort to not have the airbleed hole.  I have a couple of OS .10's that do idle quite well without that feature, as well as an AP .09.  I think the only reasons it works well is because the hole in the carb is fairly small in the first place, and the fact that smaller motor propellers and planes are kind of inefficient and will fall out of the air at a fairly high idle speed.  A large bore carb is going to need better metering or an airbleed.  I have tried running the .10's without muffler pressure, and they don't idle so well, so it is just on the borderline of working, and I bored out an AP carb a bit and the idle just won't happen at all.