I recently purchased a slightly used Extra 300XS with an OS 1.60 on it. It's running a 18x6 Pro Zinger, Perry oscilating(sp?) pump and a Turbo-Jett in cowl muffler. Now for the issues.. With the pump on it I cannot get the high end lean enough to run very well... In flight it looks like I've got a smoke system on it and it runs very rough. I took the pump out of the mix and readjusted the needles and it sounds great on the ground and runs up well but goes lean after about a minute of flight. It seems without the pump I can't get it rich enough. All the fuel lines are new and the tank is sealed and the internal pick up is all good. The only thing I noticed was an excessive amount of air in the line from the remote needle up to the carb... Do these remote needles have tendency to leak air?? This is my first large glow engine and so far I'm not too happy with it. I know it's an air leak somewhere I just can't find it.

Any suggestions would be great.

Thanks.

Back off on the pressure setting of your pump some.

Yes, OS has had issues with some of their remote needle set ups. You might try new o-rings?

Enjoy,

Jim

Thanks, I'll put that on the list of things to try... I don't think this pump has any way to set it, not that I've seen anyway. I will look a little closer tonight when I get home.

Chuck the pump. and set it up with a normal carb-tank setup.
Less factors to mess up, and known to run well.

Jett told me that the Jett In-cowl muffler provides tremendous amount of pressure. Well, he would say that.

Where is your fuel tank located? Are you using large fuel tank, brass tubing and pick-up clunk? No fueling valve?

The tank is a 24oz and it is directly behind the motor mount. When I was testing it last night I bypassed the pump and still had issues. There is now fueling valve or any of that fancy stuff on it at this point. It's a bumber too, this plane flies great....

P.S.
Also known as the KISS principle.
" Keep It Simple S***** "
*** means whatever feels right.

Serious now.
I have never seemed to get these pumps right. They either flood the engine when you play with them during the starting procedure, or they make a fool of you during flight, not to say they can ruin your engine.
The pump without the fuel demand regulator is one way to skin a cat I do not like at all when using alky engines. There are better ways. Much better ways I dare say.

I totally agree with the KISS statement. I've got it stripped down as simple as it can be..... I think I will be tearing it down and giving it a good look see. Does anybody know the factory carb settings, or at least a good starting point?

If you're running un-pumped, you may wish to try larger fuel line. The O.S. Max 1.60 is a thirsty engine, and regular line just may have too much fuel-line drag. You'll have to enlarge the fuel tubing from the clunk forward. We use a Sullivan tank and go up one size on the brass tubing, drill out the clunk to the larger inside diameter, and wire-tie all the silicon tubing to the brass.

Also use the larger tubing for the vent/pressure line.

Make sure the centerline of the fuel tank is at the same level as the center of the carburetor or no more than about 3/8" lower.

If you're running pumped, you do not use muffler pressure. The oscillating pump doesn't regulate, it just delivers, so you can get a good 'set' for full-throttle running, but it may be delivering too much fuel at other throttle settings. If you cannot close-off the fuel feed with the high-speed needle valve, then you have a problem with the needle or the needle seat. You should be able to get the engine properly-leaned at full throttle.

I think I will start with the remote needle assembly and go from there... After I make sure all that is clean and sealed I will try running it without the pump and see if I can get it to run better... The worst part about it is I have to drag it to the field every time because I can't get it to run poorly on the ground...

I have a Bisson muffler on mine and the ends of the exhaust are necked down to provide back pressure to the engine as well as higher tank pressure. At Toledo last week I stopped at the Bisson booth and asked them about opening up the muffler and they said not to since the engine needs the back preasure. Mine runs beautifully.
Sparky

Tune the engine using the pinch test, at low, mid, high throttle
the low needle may affect the mid a little also.

I had one of these engines and it was very reliable and easy to start with a single back flip

I don't know about that Turbo-Jett muffler that you are using, but I do know that the Bisson Pitts style provides marginal back pressure. The normal fix is to plug one of the two exhaust stacks. If the muffler that you are using has two, I would suggest plugging or restricting the exhaust to provide more back pressure. The stock OS muffler has only one exhaust stack, and the engine runs fine on the designed muffler.

I agree, chuck the pump and keep it simple. The less complex that you can keep your system, the more reliable it is going to be. You simply need more back pressure.

> Jim

Make darned sure the tank isn't causing the fuel to foam from vibration. If it
is, you will be chasing your tail looking at the other fixes.

FBD.

I run my 1.60 on a slimline pitts muffler and the perry VP-30. This is the one that runs off of crankcase pressure, not the oscillating version you have. I have to say it runs great. No deadsticks and consistent fuel delivery regardless of position of the tank or aircraft attitude. I generally agree with the KISS principal but in this case I could not get a consistent needle setting without the pump and I didn't want to crimp/plug my exhaust stacks. Also, in the future I plan to move the tank over the C.G..

There is always more than one way to skin a cat, pick the one that works for you and the folks at your field...
scott.

I have an OS 1.60FX with Pitts muffler and a Perry VP-30 regulating pump to pump fuel from a tank near the center of gravity. It is reliable and a strong running engine at all speeds and aircraft orientation.

I took all your suggestions and did the following....

Removed Perry Pump.
Replaces all Fuel Lines
Removed and cleaned carb and remote needle valve.
Reset low end needle
Switched to 5% Nitro and 16% oil content

Result.... The thing runs great. Thanks.

hey all you Perry pumpers I have the $6 billion dollar question!

What are your needle settings for the high/low end and pump? I purchased a used one that has the needles way off in left field somewhere and I cant get the darn thing to run! I know normally you would have the high end around 2-2 1/2 tunrs out and the low end around 2 as well but with this pump I cannot get it to run!

Any info would be appreciated

matt

Lee,

glad you got it worked out. You are more persistant than I was I just got tired of hauling that big monster to the field.

Now it looks like you got a pretty good deal, doesn't it