Good Day all,

I'm operating a Brison 3.2 with a J&A muffler tapped for smoke.

I've drilled out the smoke nipple to a slightly larger diameter to allow a greater volume of smoke fluid into the muffler.

Here is the problem. The muffler/engine combination will only produce smoke at very LOW power settings (i.e. at idle, or just above idle). At medium or high power settings there is no smoke at all.

The pump is the variety that uses alternating crank case pressure on a diaphragm to pump the smoke fluid.

Does anybody have any insight into what is going on with this smoke set up?

Cheers,

Marcus

Assuming this is a B&B type pump.

Are you sure your plumbing is correct? There should be no check valve from the engine to the pump diaphram. There should be a check valve from the pump to the muffler.

The muffler pressure may be de-priming the pump if you don't have the check valve installed. If this is your setup, are you sure the check valve is pointing the right direction - it should allow flow to the muffler and block it from the muffler.

Make sure you have a large enough line from the engine crankcase to the pump - on the order of 3/16" to 1/4" inside diameter.

These systems put out great smoke when set up properly.

Also, you shouldn't have to enlarge the nipple orifice. Most folks have to limit the oil flow to the muffler with these systems. A wheel collar over the tubing works well for adjusting the flow by pinching the tubing with the collar screw.

Everything Ed said is correct. Your problem may be too much fluid and its not vaporizing, or muffler pressure is getting back to the pump. I'm not sure how well the J&A muffler works with smoke but the Bissons make a ton.

Thanks for the Information Ed and outcast,

As it turns out I do not have a checkvalve from the muffler to the pump. I'll install one as per your suggestions, try the system again, and report further.

Cheers,

Marcus.

A friend had the same problem with his b&b system. He made the tube longer to be able to get the pump assembly out easier. He found that the tube from the crankcase pressure to the pump was to long. Shortened it back up and it works great now.

Jon

Within reason, length should not be a problem if the tubing is rigid enough. Soft tubing expands and contracts with each pulse which attenuates the pumping pulse from the crankcase. Small tubing diameter restricts the pulse and the diaphram cannot respond fully at higher RPM.

In the past I have used large diameter outer nyrod with short silicon tubing couplers and it worked well. I needed to get the weight of the Mikuni pump away from the nose of the plane for balance reasons.