Ok, here's the newbie coming out....

My OS 91 surpass has a nipple on the muffler that I think pressurizes the fuel tank.

I'm building a second plane (also a four star 60) and have a cheapie K&B 65 sportster that I want to use. There is nothing on the muffler to pressuize the tank. In this case I assume I have to run the vent line from the tank out the bottom of the plane.

My question is... Should I do this on a 4 Star 60? Does it effect the engine when flying inverted? My trainer has an OS 40 LA which also uses the muffler so I don't have any experience with the other type. Any advice to go this way or not would be appreciated. Thanks.

hoppy

My K&B 65 sportster muffler is the long straight cylinder design and has a tap on the manifold not on the muffler.

Is your muffler stock?
Dan Z

Dan,

Here are a couple of pictures of it. I got it off ebay so I don't know if it's stock or not. (the copper piece I made to hold the remote needle valve)

Pic 2

hoppy can You get a pic straight down so I can see the part where the manifold is bolted to the engine?

It looks like the same muffler I have
Dan Z

Dan,

Does this help? I can't find anywhere to connect the hose.

4 pictures total coming

Last one, other two are too big.

looks like you might have to tap the muffler and put a nipple in. It's not hard. Get a nipple from tower or LHS, the instructions will tell you how big of a hole you need.

look on the bottom side of the muffler

See that round spot between the fins next to the joint between the engine and muffler?

Mine is tapped and threaded for the pressore fitting,

How soon will You be ready to fly? You could tap it (take it to Your LHS they should help) or I can Trade You the one I have

Dan Z

Buz,

Bottom looks just like the top....

just courious, thought i saw something, but these guys are right , just get the nipple and drill the correct size hole, its a self tapping nipple

Dan,

It won't be ready to fly until spring. Cold here in Indiana. What do you want in trade? The untapped one? If so, sounds good to me.

Nevermind Dan, I found some at Tower like everyone here said. Thanks for the help everyone. Didn't know you could buy the things......

Send Me a PM

I can send this one to You first and send Yours back to Me,

Or it realy is easy to get the fitting and tap it.

NOTE" Mine is tapped but it does NOT have the Fitting, so You will still need to get one" (in my box of stuff I may have one, I'll check)

Dan Z

Ok no prob"
Dan Z

Do yourself a favor and tap the body of the muffler instead of that flat spot. That is a low pressure area, the larger body of the muffler is the high pressure area (look up Bernoulli's principle).

MinnFlyer,

Would the radius of the muffler effect how the fitting seals?

It shouldn't, the fitting comes with a seal that will conform to the shape. Besides, the threaded part of the fitting has a slight taper to it, so it should seal even if the top doesn't even come in contact with the outside of the muffler

I've been told that some K&B's shouldn't use a pressurized fuel system. I had problems with my K&B .45 always running rich. I unplugged the pressure line and now it runs fine. Try using it without the pressure line first and see how it works.

Jarodd

jdg_rit

On Your 45 was the pressure tap on the Muffler chamber or manifold?

Dan Z

Thanks MinnFlyer, makes sense.

jdg_rit,

I posted this thread originally asking if a four star 60 should fly with an unpressurized tank. Maybe I should have worded it, should a K&B.. Anyway, in general, what effect does a pressurized vs non have on an engine/aircraft??

The pressure tap was on the manifold. Hope this helps.

Jarodd

Thanks, I was just curious.

Dan Z

Hoppy

*In My opinion only,* You should use a pressurized set up when possible. It provides a slight pressure that helps prevent fuel starvation in all attitudes of flight. meaning high G turns, invervetd flight atc.

Dan Z