An inquiry to the brethren here. This fell into my lap as an RC version. It appears unrun and is a pretty little thing.  This looks like an OS FP motor inside the exhaust port. Not sure if it is ABC, ABN, or iron.

My intent is to convert it to CL without any drilling, etc. I'll likely find or make an intake stack that'll put the NVA above the boss.

I'm missing the two muffler mounting bolts. Don't want to drill and tap, but I'm not sure how to identify and find them. Perhaps they are JAL as the muffler looks like an OS. But Taiwan enters the picture. Suggestions?

Thanks.
Dave Mo...

  that should be a decent little powerhouse. I think others have used their .40 with good results.  Jim Lee helped me with some similar venturis that I just drilled and tapped a singkle hole for a spigot venturi using a rear needle valve assembly from an OS FP-.15, I think it was. These were on a Magnum .15 I think but had the same draw bar clamp for carb/venturi. Drilling all the way through should work OK also just need a bigger bore.
  Type at you later,
  Dan McEntee

Look inside first to see if its o.k. , no peeled liner or rust  . Id give it , then , a burst or two on a prime - or run it with r/c carbs , to see its not past it .
I threw a Fox 25 B B intake in a 25  . Someone was doing Goodyear intakes , blue . and needles . so a ' off the shelf ' one might be available there .
( I got two for the GP .25's ) tho I think Yr intke ole is smaller - I filed carefully a m.m. of the diameter of the Fox one to fit .

So a bit of skulldugery might be in order , if you have a spares box .

p.s. said the ABN is shiney all over , the ABC brass still on the outside . So there ya go . Looks pretty clean looking at Yr picture . BUT Still See that the Crank Web aint oxidised ( surface rust )
as it feeds off and ruins liners & pistons . so pull the back plate . Cautiously 7 you save the gasket , often as not .

Ah the gents here confirm it all - seek and ye shall find (ahem, most).

Dan: Nice option you've kindly suggested. At this point, it'll be filed away for future reference on another project. Be well my flying friend, and thanks.

Geoff: Ooh la-la, I think you've got it. The pinch bolt hole is 4mm. So this'll be my first motor with a true venturi.

Scientific: Zer goot suggestions. Casting off deer back-plate for a looky see, soaken zee gasket thingy mit all and ergs before prying. Then on to the vespugi voik.  Grakious mucho.

Bill: That diameter is 8.5 mm. As Scientific suggested, I checked my stock and no luck. I could fall back on Jim Lee or even my drill press if you've nothing in your stock.

This beauty will go into my Walter Umland Challenger 15 shown below. A bit more work is needed as you can see.

Dave Mo...

Here is a pic of one of my GP 40s fully assembled with a custom venturi and factory Thunder Tiger NVA.

The factory venturi was way too big for the GP 40 but the factory venturi for the GP 25 is just about right for the GP40.

For some odd reason, the spigots that go into the crankcase are about 0.5mm different in length so I had to use smaller O rings to fit GP25 venturis into the GP40s

A fun fact that I proved with an old GP 25 that I bought very cheap without a carb — hence the price.

The engine ran well on cold days but never looked like starting on warm days — not hot, just warm — so I installed an OS LA 25 piston and cylinder. A straight bolt in and the engine runs like a dream. I have it on a Ringmaster so, for years, it only came out for one weekend each year. A couple of turns to draw fuel up to the engine, a few flicks with the venturi open, connect a battery, start first or second flick, go fly.

On all my engines, at the end of each flying session, I fill the venturi with auto transmission fluid and flick a few times to distribute the fluid through the engine then put the model away.

Spraybar thru the pinch-bolt hole on an OS .15.  Works fine in this application.