Ralpho

I have a new os 160 in a 85 inch Roadrunner. It has as much time in the air deadstick as it does under power. The first day I flew it we noticed a leak in the head gasket. We tightened it up. Flew 2 more times and deadsticked both times. It appeared that the carb was bad and I installed a brand new carb, headgasket and rear cover o-ring. I also replaced the throttle servo with a better one that held my idle position better. I would take off, climb hard for about 500-600 feet altitude then throttle back to half. Let it run like this for 30 to 45 seconds and touch the throttle up or down and it would DIE. We used Powermaster 10% and Byrons 20/20 fourstroke fuel that my friend runs in his. More power on the Byrons but still deadsticked. My friend has 2 of these, one you could bet your life on and the other one does the same crap as the one I have.

Please someone, I NEED A FIX FOR THIS!!! I darn near bought a 2300 Tiger at our fly-in last weekend to put the O.S out of its misery.

Any help would be appreciated! Thanks, Ralph

bigchap

what plug do you use?

Ralpho

fox long rc idle bar

bigchap

have you tried an os'f' ?

Ralpho

No. All we run in our two strokes are the fox r/c idle bar plugs. If it won't run on one of those it will get traded off. That is the reason I don't have any 4 strokes yet. Different plugs, fuel, etc.

bigchap

it's a little fix i use on my recalcitrent 2 strokes,i also use them in my sons rc buggy to great effect.

fancman

My Feedback: (16)

Try the OS F plug. I didn't know anyone even used idlebar plugs anymore.

Bax

My Feedback: (11)

We normally use the O.S. #8 plug. It's just about the best glow plug you can buy for general-purpose use.

You may also want to check your idle mixture. If it's too rich, then the engine can tend to load in the midrange. It will then quit on throttle up. With a slightly-leaner idle mixture, you may need to up the idle RPM a bit. Anything under 2,300-2,500 RPM is good. Then you'll need to see which prop helps you get a good landing approach speed if you have to up the idle a bit...maybe something with a flatter pitch.

If you are using muffler pressure with a check valve between the muffler and tank, get rid of the check valve. It doesn't allow the fuel tank to depressurize when you retard the throttle, and so the idle and midrange will tend to be too rich.

If all else fails, put the engine on a test fixture to see how it goes. If it will run "all day" on the test stand, then the engine's fine, and you'll need to work with the airframe/mount/engine/fuel system combination. It will take some detective work.

Also, insisting that if it won't work with one particular plug or else is not logical. You can use glow plugs to "tune" your engine's performance. Experience has shown that there is no "one" plug that's good for all situations. You use the plug that makes your engine run best for the particular fuel/prop/exhaust system you're using, and to get the performance you want from the engine. The O.S. Type F plug may be the ticket for how your engine's fueled and propped. We can only say, "try and see". We always start out with an O.S. #8 plug and go from there.

bla bla

A Fox... with an idle bar?
Boy... are you infor a revolution when you change that!
Screw in an F type.
and if your're taking 15% (more than enough) add one extra head shim.
20% wont do anything positive so stay away.
The F type will.

telejojo

Go to a size bigger fuel line............in the tank as well.I had the same problem and bought a kit with a bigger line for your tank and stopper.It cured the problem.

Ralpho

Well, I have seen some interesting responses to my problem. To BAX: How do you address the head gasket leak? I had a LA 40 3 years ago that had problems with the back cover coming loose. I personally have a compadre who has had a FX 90 come undone with the head coming loose and the thing got so hot that it smoked the engine. He sent it back, and Hobby Services replaced it ASAP. I know that this is not a perfect world. I work fixing cars that people smash up every day!!!! I WOULD LIKE TO STATE HERE FOR ONE AND ALL THAT I HAVE HAD DEALINGS WITH HOBBY SERVICES AND I HAVE BEEN MORE THAN IMPRESSED WITH THE RESULTS AND THE ENGINES I SENT IN FOR A PROBLEM ARE STILL RUNNING TODAY, AND ARE RUNNING WELL!!!!!
Thanks again and keep the suggestions coming. Bax, email me and we can get on the ll and talk. Doggone this is driving me crazy!!!!

Thanks, Ralpho

alan0899

G'day Ralpho.
Do as Bax says & use a OS #8 plug, Type F 4 stroke plugs are too hot.
Also what prop are you running? Remember this is a 26cc engine with lots of torque, so use a 16x10 or 17x10 APC, & make sure your tank centre line is level with or no more than 3/8" below the fuel nipple on the carby, & how much running in time has it had?
You should keep it rich, for high speed needle, if you use a fine pitch prop, it needs to be rich, to allow, for unloading in the air, & lean enough on the low speed needle, that it just picks up some speed when you pinch test it, at idle.
Is it inside a cowl? if so, has it got enough air flow to keep it cool, outlet area should be at least 2 or 3 times the inlet area.

Ralpho

The answer to the prop question is 16x8 Master Airscrew Black Classic. I know, not the best choice but that is what is on there. Yes I realize that it is a 26 cc engine. I have always run bigger diameter and flatter pitch. I also don't fly my planes at the "SPEED OF SOUND". I respect airspeed for the fear of flutter because most of my planes have oversize ailerons on them for added roll performance. I have no idea how much run in the engine has. When I got it ,it was perfect looking but had some fuel in it. It was probably run some but not much. I have tuned it rich, lean and everything in between and it just won't give me a clue as to what the problem is! My friend Steve has as I said, 2 of these engines. One I would bet my life on and one that is a pain in the butt like this one of mine. Steve is an excellent engine tuner and he loves his 160. He and I are going nuts trying to figure these two engines out. I guess my next step is to change plugs like everyone thinks may help. I won't be able to do any tests till this weekend so keep those cards and letters coming with the ideas for the fix.

Thanks, Ralph

Bax

My Feedback: (11)

If an engine leaks combustion gases through the cylinder head/cylinder joint, then the gasket's bad, the head or cylinder liner are not perfectly-flat at the join, or the cylinder head's not evenly-tightened. Once common problem is an overheat that causes the aluminum to expand. This stretches the bolts, which don't expand as much, and then you have a badly-sealed cylinder head once everything cools down. Combustion leaks result.

With larger engines, you need larger fuel tubing to make sure the engine's getting fuel. It's possible that the fuel tubing's a bit small...such that the engine can't accelerate properly when you rapidly go from mid-throttle to full throttle. We don't know. We'd need to see the engine and run it on the test stand. If it will run on the test stand "all day", then there's nothing wrong with the engine, and the entire airframe/mount/engine/fuel system needs to be looked at.

BankYank

My Feedback: (63)

I had the same problem. The engine would run perfect on the bench. Mounted in the plane inverted it would run perfect on the ground but in the air it would die every time. I reluctantly bought a Perry VP30 pump and put on it and to my surprise it tamed the beast!! after some tuning and yes the tank was relocated to match the carb. Im using Omega 15%nitro and i don't remember the oil content. OS#8 Props i have tried are all APC 17X8 , 18X6, 18X10.For my stang the 18X10 is the best one so far. Also using the a Slimline inverted wraparound pitts muffler.

I had another OS1.60 in a WH Edge 73WS It was mounted sideways. Same fuel, Plug. Best prop was a APC 18X6. Slimline pitts muffler. That engine ran perfect from day one.
Pat

Ralpho

I apologise! The prop I am using is an 18X6.
Ralph

alan0899

G'day Ralph,
Sorry but that's not enough prop, you need more pitch, 18x8 is only just enough, these things are flat out at 10,000RPM, that's in the air not on the ground, so prop to suit.
And use OS#8 plug.

mscic-RCU

My Feedback: (6)

I have a friend that has an OS 160 in a Cessna 182. Couldn't keep it running until we installed a pump. Runs like a champ now. I also echo to change the plug. OS 8 or the hangar 9 performance two cycle plugs are excellent.