JeffH

My Feedback: (43)

I have a whip with a K&B 7.5cc DF. I was flying yesterday in some very nice cool dry air. Wide open, straight and level, the engine would actually run out of air. It would start missing and cutting in and out. Would a ram-air intake tube help this? This would get the intake into fresh clean air.

Rudeboy

You're sure you're not running it a tad too lean...? Or maybe you've got a fuel foaming problem at some point?

Because these engines have been sucking "dirty" air for years in DF planes, and it didn't seem to bother them too much.

Also, make sure you've got proper breathing room behind the carb. That can actually be an issue. Just last week I tested a pylon engine on my stand, and I got some really strange behaviour... apparently because the venturi was too close to my engine stand. The engine would almost quit the moment it got on the pipe and switched into the "scream" mode.

Maybe a pic and some detailed info about your setup would help out too.

JeffH

My Feedback: (43)

I know it isn't lean, it is about 3000 from peak when launched. If anything, it was too rich for this flight. Normally it unloads just right, but this time it acted funny. I have run this engine in fans as well on the whip. There isn't much room between the carb and the tank, about 1/2 of an inch. It might be sucking all of the available air out of the area quicker than it can be replenished at speed. Fuel foaming used to be an issue, but I solved that after the first flight.