Frequently asked questions


Q-    My muffler is already tapped for smoke can I use the existing port?

A-    Many mufflers come pre tapped with smoke ports from the factory. Typical  smoke nipples inject a stream of oil straight through the fitting. BDS atomizing nozzles spray at roughly a 45° angle to the centerline of the nozzle. For best smoke performance, a new tapped hole positioned to direct the spray of smoke fluid across the exhaust port window opening but not up and into the engine cylinder will produce the best results.  

Q-    Do I really need a check valve?

A-     A check valve will prevent siphoning of smoke fluid through your pump which can lead to a lag time or “smoke dribble” when the smoke pump is switched off. Positioning a check valve just before the smoke nozzle will reduce the lag time and provide more positive smoke switching during your routine.

Q-     I’m setting up a twin cylinder setup and plumbing diagram shows multiple check valves. Why?

A-     A single check valve before a tee fitting split will allow venting between the lines to each nozzle. Uneven exhaust backpressure between cylinders can cause exhaust pressure to force smoke fluid to the cylinder with less backpressure resulting in slow switching, lag time or “smoke dribble.” Equal lengths of smoke tubing after the tee fitting all the way to the smoke nozzles is just as important in keeping equal backpressure.

Q-     Do nozzles require cleaning?  

A-      If running a rich fuel to premix ratio nozzles can occasionally carbon up. Most nozzles can run for years with out issues. A good practice is to remove and inspect smoke nozzles at the end of a flying season just as you would inspect or exchange fuel lines. If nozzles should require cleaning a simple soak in a carb dip such as barrymans carb dip and a scrub with a fine wire stainless steel or brass brush works well. A pipe cleaner and acetone can be used to clean the nozzle interior followed by a careful backflush of compressed air.  More aggressive cleaning risks damaging the nozzle and spray pattern. Please never pick or poke anything into the tip of your nozzle.  The tip can be damaged and spray pattern compromised.