This web page was last updated on April 23rd, 2017; thanks for visiting!

Above: This is a NEW, never run ZENOAH G25B-1 Engine system, which includes the recoil starter, belt reduction prop drive, Mickuni 'butterfly' combo carburetor and fuel pump, ignition coil, FISHER tuned pipe/ silencer exhaust, motor mount, and a Tennessee Prop GA56x27 for a pusher installation. (Parts are loosly set in place for these photos to give an idea of how it all goes together.)

Above: The MIKUNI "Butterfly" combo carburetor and fuel pump has adjusting needles on either side of the carburetor body for both the high speed and low speed mixture adjustments. Arms with connectrs for both the throttle & choke allow for easy cable connections.

Above & below: The FISHER custom tuned exhaust was designed for an inverted engine installation on the Mitchell Wing (B10 model). It's shown in it's installed position in the 2nd photo below.

Above: This is the G25B-1 engine in the inverted installation in the Mitchell Wing. Note how the FISHER exhaust wraps around the front of the engine in this pusher setup. A friend of mine has flown a Mitchell Wing B10 he built with this engine system in the South Park region of Colorado at 9000+ heet ASL.


Model 250CC Engine Notes
TYPE Upright single cylinder (upside down for the k-wing) 2 stroke air cooled
Displacement (cu. in.) 14.78   (242cc)  
Bore x stroke (in.) 2.835 x 2.343      (72x59.5mm)  
Compression Ratio Nominal 10.6 : 1 Effective 6.5:1
Max output 22hp @ 6,500rpm; (25 h.p. with tuned exhaust) with a test muffler (muff not supplied)
<Exhaust gas temp limit Not to exceed 1,022F   (550C)
Cylinder Head Temp. Not to exceed  446F (230C)
Rotating Direction Counter Clockwise from PTO  
Lubrication System Gas oil mix Ratio 25:1
Lubrication Oil Spec High Quality 2 stroke oil Note: don't mix oil types
Gasoline Spec. Regular Automotive higher octane is better
Carburetor Diaphragm type with pump  
Ignition system Breaker point type Flywheel Magneto and ignition coil Newer Models have CDI ignition
Ignition Timing Retarded 6 B.T.D.C. Advanced 21 B.T.D.C
Spark Plug Champion N3, NGK B8ES  
Net Weight 38.6 lbs. with recoil starter 35.3 lbs. without starter
Dimensions   (LxWxH) 11.81 x 11.57 x 14.84  in.  

Serial # 406-60-4470 engraved in the bottom of the case

The new bare G25B-1 engine was last being sold for $2166; combined with all of the other components included in this complete system, if available today the total cost would be well over $3500.

This one complete system is available for $1650. It is available for inspection & pickup in Fairplay, CO, or you can pay packing and shipping charges; I'm estimating about $130.00 for FedEx ground within most of the continental U.S. You can call BRUCE at 719-836-2489 if you have further questions.


Below : A Tennessee Prop size 48x20 Drilled with 6 holes in a 3" circle with a 1" center shaft hole, 1.5" thick hub. For Sale at $175 + $20 shipping

This was an undersized prop placed on a F33 engine for breakin purposes- it was never flown. There are no nicks or chips anywhere on this prop- only the discoloration where the prop plate was bolted in place and left for a while. Aluminum plate and 6 allen head metric SS bolts are included. current price to make a new one this size is $361

BING 54 Carburetor : Used. Was in good running condition when taken off my HIRTH F33 engine. Comes with some extra jets included. $130.00 plus $15.00 shipping.

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