Ok guys, bear with me, I'm new. Just bought a new 46 SF on you know where. Came without instructions and in a box that says it's ABC. Looks like it has a ring when looking into exhaust port. I know that they came both ways so how can I make sure. I just want to make sure since I know that break-in is different. If it is ringed, I start with 4 cycleing rich and just lean it a click or two with each tank? I know what to do if it is ABC, run it full throttle in a rich 2 cycle and maybe heat the cylinder with a heat gun before starting. Anyone familiar with these engines. Thanks Dave

The SF .40 is an ABN engine!
Regards!
Jan K

You are on to a gem!

I don't now if the ABC is chrome or not but the SF never exhibited the peeling liner problem of later OS engines.
I have several of these engines and really like them a lot.
The ABC version does not have a piston ring.

Your running in techniques are allright. I don't think you will need a heat gun though.

/Red B.

The OS .46SF came both as a ringed and the ABN version. I think this was the first of the ABN engines. I have the ABN version and it peeled badly. A buddy had the ringed version and after years, he replaced the ring and it is running fine.

Dave:

Look in the exhaust port. If the vertical parts you see around the cylinder are steel colored, and there is a grey ring around the piston about 1/16" from the top with the grey ring also about 1/16" wide, you have the ringed engine.

If the vertical parts you see are brass colored, the engine is ABC. Highly improbable, as Ed M. said.

If the vertical parts are sort of tarnished silver colored, it is ABN.

Hope this helps.

Bill.

mine is ABN, 15 years old. runs great, sips fuel.

Congratulations, you have TWINS! Can anyone suggest a worthy project? I know that Ed Moorman recently built a Twin Air. Regards to all!

The Twin-Air 40 is the best around now. Easy to build, and easy to fly. www.ne-aero.com

The Duellist 2/40 is an excellent plane, but it's not being kitted now. Plan still available. Fully aerobatic, but a lot more skill needed for the build.

Quick and dirty ARF, check the Twin Stick from Cedar Hobbies. 40-46 and not expensive.

Bill.

Thanks guys....Took the head off and looked at the liner, underside of lip looked like brass. I didnt think to try a magnet at that time. About 1/8 inch down there is a line (dark) on the piston. I think it is ABN, has the same box as above. The Yeager post. Dave

Dave:

I hope you saw the brass without taking the head off. If you see brass inside the cylinder bore your engine WAS an ABN. It has been converted to junk, the liner has peeled.

For the price of the OS piston and liner set you can buy a much better engine.

Bill.

William....Not inside, under the lip which sits on top of the crankcase, on the outside, there is no brass showing on the inside. It has very little run time on it, maybe 1 tank. Thanks Dave

Bill,

Thank you for your experienced input on a twin project.

Northeast Aerodynamics has some great designs. I have a SportAir .60 (scratch built from SportAir .40 plans blown up to .60 size.) It is an absolute delight to fly and land. It literally lands itself! Just get it over the end of the runway and let go of the sticks! I'm sure that the TwinAir flies just as well.

There was an interesting thread in the Multi Engine Forum on a TwinAir build with dual vertical stabs. I thought I had it bookmarked, but can't locate it now.

Bob:

Walt's (Build-n-flier) twin tail Twin-Air build thread is [link=http://www.rcuniverse.com/forum/Twin%2DAir_45_build_thread/m_1355375/tm.htm]here[/link].

Bill.

Bob:

Additional: You may be interested to know that Walt's development of the twin tail construction is the design John Marien/Northeast Aerodynamics includes as the rwin tail option on the Twin-Air 45.

Further, the Twin-Air 45 is nothing more (or less) than the Sport-Air 60 in a twin engined conversion.

Bill.