Originally Posted by StZ

Is the Fox RC Long with bar a four stroke plug?

NO... Fox makes a four stroke plug but not near as good as OS F plug(four stroke)
Fox also makes RC long without the idle bar... but I had the same results with the Fox RC long plug (with idle bar) being better than the OS plugs for OS 2 stroke glow engines. Cheaper too.

Thanks for clarifying.

I am having the same problem with my OS 1.60 engine.
It quits in flight, sometimes after a few minutes of good performance..
It idles perfectly, with instant acceleration.
I set the needle to about 200 to 300 RPM below max.
I have gone thru the tank system many times.
The idle screw is set very close to the spec (1 1/2 turns open from where screw bottoms with throttle barrel just closed)


I am wondering if the OS#8 glow plug is a problem (although it is one of the recommended plugs)
Would a hotter plug or a colder plug help...?

I had an increase in performance when changed from no 6 to no 8 plug on my OS 91FX during the hotter summer months. I think it would have similar effect on your OS 1.60.

Get an auto on board glow plug booster it helps a lot .

This the I use http://www.singahobby.com/?q=node/21798

South Herts Models Advanced Glow Switch

I had a problem with full throttle in vertical position with my glow engine OS 25 FX Yak-54. When holding a plane horizontally, no problem at all, but as soon as I positioned it vertically it just died after a couple of seconds.

Just for kick what I did, I removed the tank and positioned it right next to engine ( like in RC helicopter) using aluminum bracket. I did this not for the flight but just for testing it vertically for full throttle. Guess what? It worked great. I hold my plane vertical for a couple of minutes many times going full throttle. No problem at all with the same tank.

Also I checked my tank by submersing it in the water and with pressurised air . Perfect, no problem, no pin holes.

If your Rc airplane with the glow engine don't hold a full throttle vertically in 99% of cases most of the problem is the long distance between fuel tank and glow engine carburetor.

You have to almost position it behind the engine within half inch from the back. Also your tank must be short and thick rather than long and thin to carry certain volume of fuel.

My Yak 54 were pure designed and the fire wall didn't allow to put tank right after engine. So I end up with positioning it far inside of the plane which was the problem for vertical flight.

I reworked the fire wall. I made a hole in it and positioned the customized tank right after engine ( half inch from the back). Now everything is ok. It works great.

Actually RC Gasoline engines have build-in fuel pump and they don't have problem with a vertical throttling at all. So that’s the good alternative to glow engines.

Actually glow engine helicopters don't have a problem with the vertical flight engine stole. That's because fuel tank is positioned very close to engine.

So the glow engines are very sensitive to fuel tank positioning. Unfortunately in RC airplane you cannot place the fuel tank anywhere. The only the position is right after engine which complicates the design. In some cases you have to rework the original frame to let it happen.

Probably its possible to place two small identical fuel tanks with two clunks and common fuel line in the Yak-54 cowl right next to the glow engine ( to the right and left next to the carburetor) kinda like in helicopter. With that kind of design no more worries to fly vertically at all. It will fly like a helicopter. Or maybe to build just one big out of empty tin to fit inside of the Cowl opposing the exhaust pipe. But if you crash your airplane nose down, it will be a complete disaster with firework

FiberT what you have done is very useful since you can eliminate many errors should the engine run fine when the tank is positioned very close to the engine. It is a simple thing to do and would save considerable time when trying to find out where is the issue on a poorly running engine.

I had a fx90'and it never ran right.. turned out there was a harmonic frequency that would make the backplate mounted needle valve vibrate and let in a nice slug of air..even though it had fuel tubing over it. . I finally saw it happen on the ground.. I ditched the remote needle valve carb and replaced it with an old regular carb from the junk box...

That said, change the plug, flush out the carb. Reset the needles and start from scratch...

I always used fox r/c long with an idle bar... some motors liked other plugs better and would maybe turn up a bit more with an exotic plug, But I never ran into a motor that wouldn't run satisfactorily with the fox plug.

Good day all. There is an engine sealing procedure for glow engines that solves many issues.
Beat done out if box before first run.
Remove carb and needle valve assembly, remove back plate and gasket. De grease all with alcohol and re assemble with a very thin coat of red hi temp silicone to all mating surfaces. Carb screws to be silicone & locktited also. Carefully re assemble the entire needle valve section using silicone seal. Don't let any get inside needle hole! Too much silicone on back plate or anywhere will end up in the glow plug and kill it!
Now the "pump section" is perfectly airtight!
I also seal muffler halves same way.
Last thing make sure the fuel tank is vertically balanced with the carb! Also close behind the engine. The biggest design flaw over the years is an upright engine that is set way too high on the firewall, with the tank low. Best to mount engine sideways to level up with the tank.
Prepared over 20 engines and they all run like a clock!

Also carefully filter your fuel, from the bottle and use a good filter behind the carb. Always re fuel from behind the filter.
A floating debris inside the carb housing can come up and block the hole during high fuel flow, making the engine die suddenly at hi throttle. So remove carb and blow it out.
Also I use OS#8, A3 and Traxas silver (hot rc car plug). 4 stroke plugs are great too but expensive.

I always run fuel through filters before entering the tank so there is no issue with debris.
The engine finaly run without any issues following a complete breakdown, clean up, sealing, changing the plug and positioning the tank a couple of inches closer to the engine. I did it all at once since I did not have the time to do seperate testing.

Glad to hear that your OS engine is now running the way it should.