4 stroke cuts at end of outside loop

are you sure the clunk is far enough away from the tank end?

It will fly OK inverted, its just the outside loop that causes the trouble. Might get a perry pump for it, and also the fuel lines could be shortened, they are needlessly too long.

Yeah, the clunk does not touch the rear of the tank in any orientation.

even under -G and suction from the motor ,it has to be fuel lines or tank I would think

bottom end to lean? I would have thought you are going to be at somewhere near full throttle at the end of a bunt

Doesn't it depend which way you do the bunt ? If you start low then roll to inverted and bunt from there then you will finish at low throttle. If you start high and bunt from upright level flight then of course you do end up at full power.

Maybe the OP can tell us which way he does his bunts ?

from the top, flying level, push the nose down.........plane is inverted at lowest point engine doesnt want to get up to full power on the climb out, cuts at the top.

Maybe the fuel tank's too high in the fuselage or there's a lean spot in middle of the throttle range ?

Is it a Laser or a Weston engine where the carb is directly behind the top of the cylinder head ? If so then you may need to take special action to ensure the tank mean level is centered on the carb. Usually, engines have the carb mounted nearer to the crank axis and if a plane has been designed with this in mind then the tank position may be wrong.

As an aside, does anyone know why these two engfines have that peculier layout ? Quite apart from the tank position issue there is the problem of ensuring enough room for the engine to breathe between it and the firewall.

I always thought a loop started from inverted was called an inverted loop rather than a bunt

Try richening your idle.

fred wrote:

@Boo: Putting the carb directly behind the jug shortens the intake manifold and helps prevent carburetor icing. Used to run into that with one of the first Saito 80's.

@ Fred: Richen up the low end 1/16 of a turn.

In article , Six_O'Clock_High

Thanks for all your comments.

Dug out the instructions and the factory default position for the low end idle is: Unscrew (ccw, richen) low idle until it stops, then screw back in 6 turns.

Mine seem to be screwed in a LOT more than that, which could account for the lean setting.

Got the tank back in, the plane is ready to fly with the cowl off for easy needle access.

It also keeps the elephants away. That gets a *real* problem on outside loops.

yup. Elephants LURVE them Saitos.

Fred --

It sounds like the tank might be mounted too high in relation to the carb CL. In this scenario, you would have to run the engine on the lean side to get normal ops; when you go inverted and put some negative G's on it, the engine would really go lean causing your sag.

Cheers -- Lyman

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