While we have the dynamic Duo here, I have a question on a new non-Evo 102 BME. Here are the basics. About 3 gallons through the motor. Running a Menz-S 26x10. Tachs 6300 rpm. Sounds and runs good on the ground. Runs good in the air for 5-6 minutes, then starts to sag and lose power. Checked the cylinder temperatures and it's very hot (260F on both cylinders). The cowl is baffled. Tried richening the mixture and it just never makes good power. Flew it without the cowl, both cylinders now around 205F, but still sagged aft 6 minutes in the air (at full throttle). Fuel was Lawnboy 32:1. Tried a couple of tanks of Mobil MX2T synthetic, same problem (maybe it ran a little longer before it started to sag). Engine has good compression hot or cold. Swapped ignitions, no difference. When the cowl was off, noticed some oil around the snout of the crank. Thinking maybe it's a crank seal leaking air? Or is a Menz-S 26x10 too much prop for this motor?

It's not my motor, but yesterday I was trying to help the owner who has been struggling since last season with it.