Cub Man

My Feedback: (50)

I received a plane from a friend. He had flown it probably a few dozen times. It is equipped with a Zenoah’s G23. I have flown it several times also. I use Klotz oil mixed at 40:1 Engine runs great, but it is still spitting out a black from the muffler. It is not a shiny black. Suggestions running stock muffler and about to extend the pipes to keep the crap off the plane. I have several gas burners, use the same fuel in all of them, this is the only one that is giving me this issue

soarrich

My Feedback: (98)

It's not broken in yet. The black crap will stop after it's broken in.

paof

HI CUB MAN TRY SAME OIL BUT MIXED 30 . 1 AND CHECK YOUR EXHAUST.

PAOF

w8ye

My Feedback: (16)

Change to electric and there will be no more black.

av8tor1977

My Feedback: (6)

The past owner may have been using an oil that carboned up the engine and muffler, and/or he may have been running it way too rich. (Some people do this from a left over "glow engine mentality".) It probably won't quit until all the carbon gets blown/washed out. I would dare say that after "a few dozen flights" the engine should be broken in enough not to spit out a lot black gunk unless it got carboned up.

W8YE - You're "bad".

AV8TOR

Tired Old Man

My Feedback: (1)

I've had numerous engines were they were still providing signs of the break in after 10 hours of run time. Those have generally been big twins. There have been a few break in time experiments that have illustrated break in will not be complete until 7-12 hours have been accumulated on high quality small engines. I mentioned high quality (Zenoah is one of those) because the lower quality engines have the ability to never achieve full break in because of poor machine tolerance standards.

How the high quality engines were run greatly impacted the break in time. This also applies to less than steller quality products. Rich, cool, and low RPM makes for an extremely long and incomplete break in. I agree with the possibility of the previous owner using a crappy oil since it happens all the time with manufacturers that sell particular brands of oil promoting continued product sales.

av8tor1977

My Feedback: (6)

I didn't mean to infer that the engine would be completely broken in with so little time on it by any means. However, after a few flights none of my new or rebuilt engines seem to put out much black glop.... I use Pennzoil for Air Cooled engines at 32:1 for break in, and tune for peak while carefully avoiding lean.

AV8TOR

Tired Old Man

My Feedback: (1)

I know you didn't I just wanted to better explain the length of time required to finalize the break in process. Too many manufacturers make allusions of a gallon or two and bingo, it's done. 3 gallons done wrong and the process may not even be started yet.

av8tor1977

My Feedback: (6)

As our "down under" friends would say, "No worries mate!"

AV8TOR

Cub Man

My Feedback: (50)

Thanks for the info. I do have a few electric, but I do like my big gas planes