This is my first gasser.....How do I plumb the fuel tank? I know about tygon. Is it a vented three line, or pressurized? The walbro carb has two connections. What are they for? Thanks for any help.

I'm working on my first gasser too. I think the connection on the bottom of the Walbro carb is supposed to be conected to your crankcase line. The pulsing effect of the crank and piston is what works the pump in the carb. There's a little diaphram in the carb and the pulsing line from the crankcase works the diaphram to make it pump.

You will not need tank pressure with the Walbro carb. So, you only need a clunk and a vent. Some guys use a third line to fill the tank.

I'm no gas expert, there are plenty of them lurking on these boards. I'm sure you'll get plenty of help from more experienced guys here.

The Walbro carb gets it's crankcase pulse through a hole in the carb mount attached to the cylinder. That is, unless the previous owner tapped the diaphragm cover and tapped the crankcase so that a different carb stand-off could be used.

Usually the Walbro carbs that have two connectors have a primer bulb and the connector on the carb body goes to the tank suction line with the outlet on the bottom of the prime bulb to a vent line.

Crankcase line??? Where is that located? I just had it running and I can't get enough fuel. It was running real lean but I could throttle up and it would hold but when trying a vertical she would quit immediately. There is not two needles on this carb. Just one and I can't seem to get it rich enough so maybe it isn't pumping.
Windchill in Mi right now is -10. Too cold for sane people but not for me. Is it to cold to get this dialed in? Thanks for the replies friends!

What engine are you using? Use LARGE brass tubing for the tank and LARGE fuel line for the pickup. Clunk line goes to fuel inlet at the carb, the other line (vent) gets run out to the bottom of the plane and left open. DO NOT use mffler pressure on the tank! This creates the possibility for explosion or fire. You can use the third line for fueling if you like, just remember to plug it after fueling.

It is a 21cc weedeater pulled out of my wife's favorite tool. It converted easy enough but I don't think it has a top of the line walbro carb. Where should the tank be located? The same as with glow engines? The engine is mounted inverted and this puts the carb very low in relation to the tank and I am getting some siphoning.

The tank can be mounted anywhere, with this type of carb. also you don't have to use any larger fuel line than you would normally use.

Thanks Jemo, Does this carb have a low speed idle other than the throttle screw? There is a large chrome screw on the side of the body that I don't know if I should mess with or not.

You should have two needle valves. The one closest to the engine should be LOW.
The large chrome screw is (I hope) the throttle stop screw. As long as you are controlling the throttle with a servo you don't need this , just back it out so it cant stop the throttle or just remove it. Make sure it is the throttle stop screw before you do anything.

If you have a carb #." rcign " will tell you anything you need to know about it.

There are some carbs made with a fitting in the back cover for the crankcase pulse..If the carb has no fitting the pulse comes from the hole in the carb in insulator block...If the carb has only 1 needle the high speed mixture is fixed, set by the maker for the size of the weedeater line and the rpm they want..no way to change it...If it runs at all the pump is working..The carb will work in any attitude, so if it slows down maybe the filter screen is dirty

Thanks RCIGN, Yes the ONE needle did have a red plastic cover over the adjusment restricting movement of the needle to only about 1/2 turn. I took that off and can move it normally. I am running a vented tank with two other clunk lines. One clunk feeds the right side connection on top of carb as you look down the barrel, and the other to the left connection, also on top of the carb.

I just located the walbro number for this engine it is wa 218.