Hello all,

I have recently completed my Sig Rascal 40 and put in a new TT .46pro. My problem is this.... the top end runs great ,11.5 x 4 prop @ 12900 rpm, but I can't seem to get the low end idle below 3500 without the glo driver on it.

I have tried to adjust the idle mixture with limited success. Could it possibly be the glow plug itself???

Please give me any feedback you can, I need fresh ideas.

Thanks

There is a good chance the plug may be somewhat defective, or it may be too "cold" for your set-up. Try a K&B idle bar plug, and the OS A-3. Also, you might have the idle too rich, but try the plug change first.

Clair

get a OS # 8 Plug and see the diference

Thanks for the response guys, I believe that the plug in it is the stock TT plug. I've got some OS#8's and wiull try that tomorrow.

Thanks

Keep us posted on your trials. My TT .46 pro is will load up at idle even though I keep leaning it out. Still playing with it. May yank the old plug out and try an OS 8. I like these very much. Well have to see if it works.

bdtsr,

Is your TT mounted inverted? Mine is inverted. I pulled the plug out lastnight and found it to indeed be an OS #8. I changed it anyway and will try again. I have noticed that when I leave the glo driver on I can idle it down to 17 -1800 rpm and it just purs like a kittten.

If you are running inverted, a good idle bar plug can help a bunch. The bar helps shield the glow element from the cold fuel comming into the engine, which helps keep the elment hot. It's not always the fix, but it's a cheap test.

Also a higher nitro fuel could help with the inverted set-up. Good luck.

2fast4u hit it on the head. Many engines have problems with inverted mounting. Having the engine well broken in before mounting it this way will help. Mine is on it's side. The carb just seems weird. In order to adjust the low end you have to open the throttle some, otherwise it seems to bottom out. The engine was never run before and I'm the 3rd owner. It is mounted in a Global Tecate Bipe and the previous owners thought it would be too much for them. They should have given it a chance, it flies quite well, even when the motor quits!

Hi!
Why have you mounted the engine inverted!!?? This is the wurst position for an engine.
Always mount your engine on its side .....or tilted down some more like 60-75 degrees...but not inverted. This is begging for trouble.
But most engines run fine inverted ....Have you checked your fuel....5-10% nitro works perfectly in most engines and certainly in your TT.46 PRO SE. 15% nitro or more could in some cases mean bad idling an over all bad engine running behavior.
And how about the fueltank...its center should be in line with the fuel inlet orifice in the carb when the airplane is horizontal and the tank should be mounted as close to the firewall as possible...not 10-15cm from it and in lots of soft foam..not tightly press-fitted between the formers in the fuselage like in some Kyosho airplanes.
How about tank size ..this is also vital. You should use a 8-10 oz tank.....not bigger. And you should also check your fuel lines..there could be a hairline crack somewhere. Do not to large fuel tubing..inner diameter should be medium (1.5-2mm) and as short as possible.
Fuel pressure from the silencer to the tank is also a must.
Glow plugs from Enya (No 3) or OS (No 3 or 8) should also be used .
Also check the backplate on the engine and head bolts plus the carb fitting.
When you say that the rpm drops when you take away the glowdriver from the plug ...this is a symptom of using to little nitro or a too cold glowplug
Your engine should idle at apprx 2000 rpm on a 11x6 APC prop.

Regards!
Jan K
Sweden

The engine can only be mounted inverted, I just started assembling mine and mounted a PAW .40 Diesel in it. A Fox Gold Post idle bar plug will make a huge difference also.

Hobbsy's got it . Inverted it the only way to install the engine in the Rascal. Thats just the way it was designed.

Now, about this idle bar what is it and where can I find one?

Jank: the rpms don't just drop when I take the heat away, it flat out dies.

Every pattern ship and control line stunt ship that I have seen for the last couple of decades utilizes inverted engines. Not all of them were powered by a YS four-stroke engine. Many have been powered by two-stroke sixties and four-strokes of other brands. All performed flawlessly when the operator knew what he/she was doing.

All of my models, whether sport, fun fly or pattern are expected to have the engine running at the end of the flight. I perform inverted spins, slow inverted flight, inverted flat spins, etc. I have yet to meet an engine that cannot be made to run well and reliably inverted.

So what is the secret? Set up, fine needle tweaking and proper break-in. Not necessarily in that order.

Break the engine in properly on the bench. If the engine is showing any sign of a problem with reliability after you have tried all of the variations available to you, send it back for servicing under warranty with a note describing exactly what you have tried. Sometimes engines leave the factory with unknown defects. There is absolutely no reason why you should have to put up with a defective product.

Once your engine is broken-in properly, ensure that the centerline of the model's fuel tank is slightly lower than the spraybar of your carburetor. Usually, no more than 0 to 3/8ths of an inch is the proper amount. In short, nothing else will do. Any higher or lower will affect the running of your engine, unless it is a YS, pumped other brand or an engine using a Perry VP-30 pump or other third party regulator. An engine is not defective if it is suction feed only and the fuel tank is not at the proper height.

Use glow plugs that are recommended by the manufacturer. Believe it or not, they generally know what they are doing.

Use the recommended fuel for the engine you bought. Too much nitro in some engines can cause as many problems as not enough nitro in the fuel for other engines.

Use a prop within the recommended range suggested by the manufacturer. Overheating will ruin an engine much faster than over revving. Keep that in mind.

Make sure that plenty of cooling air can reach the engine. Equally important is the exit size for the cooling air. Since the cooling air is now hotter, after cooling the engine, it will expand and it will need a much larger exit opening than cooler incoming air.

No one is born knowing how to do this stuff. Those that do know spent the time to learn. Many also look back and realize that the learning process was the most fun. Don't feel bad if you don't know how to make it run right. Get determined and figure it out. You can do it. I did.

Good flying.

BigSky,

All you gotta do is ask for an "idle bar glow plug" at your local hobby shop, or type "idle bar glow plug" into a search engine at your favorite online hobby shop. The difference is quite noticeable. Idle bar plugs have a little chunk of metal on the end, partially blocking the glow element. They were necessary on some of the older cross-scavenged, pre-Schneurle-ported engines because they would literally splash gobs of fuel around, and occasionally a gob would hit the plug and put the fire out. Modern Schneurle ported engines normally don't need idle bar glow plugs because the fuel is mixed with the air better.

Frankly, I don't think an idle bar plug will help at all. You need to lower the fuel tank if possible, and keep leaning the low speed mixture (inside the throttle arm). Right now, the tank is certainly higher than the carbuertor, and is pushing too much fuel into the carb.

The Rascal is designed with the tank positioned correctly for the inverted engine.

"Frankly, I don't think an idle bar plug will help at all."

Trust me on this one....I had it proven to me over 25
years ago....blocking the fuel from the fire with a
barrior....will not promote a better idle. They should
call them "non-idling barred plugs". They're junk.

You especially won't like them when the idle bar breaks
off, and destroys your motor....which does happen.

You might give one of these plugs a try, the Fox Miracle
plug. They work great in two-strokes for two reasons.
First they have an extended tip design that does not allow
raw fuel to collect inside the plug....and they are a hotter
plug....which will help with some rich conditions that
occur with inverted engines.

Dave.