[] I have a K&B 61 that is giving me fits on low idle... It has old perry carb and we dont seem to be able to keep it running. When we lift plane up , engine seems to starve and die..... Is there proper settings that anyone can help me with ? I am a newby and would like any help given..... ?

Robert,

I copied my input from an older thread and changed what was necessary.

Verify your fuel lines are as short as possible, but the clunk still reaches within 1/8" off the rear of the tank. It must be insulated from direct contact with any part of the airframe, by 1/4" foam latex, to prevent vibration and foaming.

Verify the tank centerline is within 3/8" above, or below the carburettor spray-bar.

To adjust the engine, start with a rich main needle setting and with the idle disk set in the middle.

Set the throttle to full speed and lift the plane's nose straight up.
It is preferable that someone will hold the plane firmly, while you adjust.

Close the needle gradually until closing further doesn't add speed, or causes a loss thereof. Then open the needle back until speed is 100-150 RPM below that maximum. It is imperative that this is done with the nose straight up, to simulate the situation that is most difficult for fuel draw. That would do for now.

Now set the plane on its landing gear and close the throttle to idle position (about 1mm open).
Listen to the engine carefully. If it sags gradually, it is too rich. You should turn the idle disk to the lean direction, about a click. This adjustment method is very sensitive. The entire adjustment range is about 3/8".
Advance the throttle gradually to full for a few seconds, reduce back to idle and listen again.
Repeat, until the engine runs at a stable idle speed.

If, on the other hand, the engine gradually speeds up at idle, it is too lean. Do the exact opposite of the previous paragraph (turning the idle disk to the rich direction).

From this baseline, check transition from idle to full power.
After running the engine at full speed for a few seconds, close the throttle to idle and keep it there for about 30 seconds.
Now open the throttle rapidly.

If the engine immediately accelerates, you are done.

If it sputters fuel before eventually speeding up, or dying, it is still too rich, lean the disk very little and try again.
If it hesitates (coughs...) before eventually speeding up, or dying, it is too lean, richen the disk very little and try again.

After you are done with the idle adjustment, re-check the main needle adjustment.

Robert:

Dar is correct in his method of adjustment, but he makes it sould a lot more complicated than it needs be.

Start the engine and go to full throttle, turn the needle in and out to get the fastest speed the engine will run, then unscrew the needle just a bit, until the speed drops a little bit.

Then close the throttle as far as you can and keep the engine running. Pinch the fuel line shut.

If the engine dies immediately it's too lean, Turn the mixture disc just a hair, moving the little notch toward the front of the engine and try again.

If the engine speed immediately rises when you pinch the hose, it's too rich. Turn the disc so the notch moves toward the back of the engine and try again.

The third possibility is the engine speed staying the same when you pinch the tube for a second or so, then the rpm will rise a little, and finally the engine will drop rpm. This is very close, from this point adjust the idle mixture asDar said, judging it by the way the engine answers the throttle.

All this supposes you have no problem other than the adjustments. But there are other problems you may have.

First, is your engine's carb a pumper or a suction version? Look at the first picture attached, if your carb has the extra screw like the one on the left it will not work satisfactorily without a pump. Wont even work with the Iron Bay or Cline pressure system, it requires a pump. Look at the second picture, the pumper is the top left, normally aspirated carb is top right. Might see the difference more clearly here.

Assuming you have the right carb the idle slit could be clogged with congealed oil, or its o-rings could have failed.

Take the carb off the engine, unscrew the needle and set it aside. Remove the circlip from the side, and the idle stop screw. Pull the throttle barrel out. Now pry the mixture disc out of the carb body.

Look at the third picture. The part shown is the K&B adaptation of the Perry, yoursw is not quite the same. You can see the hole on the side of the tubular extension, this is the idle slit that clogs. On your carb the slit is in the land between the two o-rings. Clean it with a small bit of typing paper wetted with acetone, don't use anything but paper - the size is critical and can be damaged. If there is any damage to the o-rings order a new set from Conley Precision or MECoA, they're not expensive.

Reassemble, adjust, and enjoy.

Bill.

PS: Before youo do anything to the carb check for air leaks, around the base of the carb, the engine's back plate, bubbles in the fuel line, and so forth. wr.

Thanks for the help.... I was thinking about ordering a new carb from Tower. I purchased this engine off of E Bay and when it got here, we found that the carb had been jb welded to the engine. Another flyer gave me another carb and this is the one we are trying.... Also the one from e bay had the needle valve glued into the housing. I am considering purchasing another carb that is new. The problem is Tower wants $35.00 and Mecoa wants $45.00 but I can purchase a new engine with my engine for trade in at $80.00 from Mecoa. I guess I just have to figure out what is best for me and the most trouble free. Lack of knowledge is a terrible thing........ Both of you gentlemen were very helpful....[8D] [email protected][]

Robert:

If you'd like, send me the engine. I'll check and repair as needed, send it back. I've done it for others, no complaints yet. Except I'm sometimes a little slow sending one back.

Email/PM me if you're interested.

Bill.

I use the magnum .46 front needle carbs on the K&B .61's. I used to
use the OS 7B carbs, but they don't make them anymore. Wrap the
flange of the carb with a few turns of teflon tape....twist the carb in real
tight, and tighten the screws.

Dave.