SkyHawk 66cc Gt5A-ES ENGINE only: includes OCDT & Free Shipping

Grubee Inc


Skyhawk Gt5A-ES easy start engine LONG BLOCK:   Heads up! an OCDT is Included. 


 Includes: the world famous SkyHawk Gt5A-ES 66cc engine $129.00 value. 

Engine made by YuanDong factory in Jiangsu China.  Same folks that make the YD100 /LD 100 and 85 Avenger. 

Includes OCDT = Over-Running Clutch Drive tool for handheld Electric starting.        $36.95 value.

Includes:  HP TZ CDI red wire high output ignition: $18.00 value 

 Includes:   7 pcs front mount shim kit:  $12.95 valve 

 Includes:  USPS PRIORITY SHIPPING:    $22.00 value   Normally, 2 to 3 day travel shipping.

 Includes:   3 Pt electrode spark plug.      $5.00 value 

 Includes:   46cm long rubber fuel line.  $ 8.00 value  

Includes:    Fuel line filter                          $3.00 value                                                                          Total value $234.950

Notice:   We no longer sell our engines on eBay or AMAZON. 

ENGINE DETAILS:   66cc /  2.7HP  47mm X 38mm BORE AND STROKE:  It's said by many folks to be the most powerful stock high rev 66cc 2 stroke bike engine ever made. Gt5A-ES is Made by the YuanDong engine factory, same folks that make the YD/100, LD/100 and the 85 Avenger.

The 38mm short stroke can rev somewhat quicker than a longer 40mm stroke.    It's the small block 350 Chevy of the China Doll bike engines.    

The Gt5A 66cc Cylinder has a round exhaust port that mates to a round exhaust header pipe for more smoother exhaust flow.  Obviously, oblong rectangular exhaust ports do not match round pipes!   

Completely assembled and run tested.

The CCW threaded crankshaft is the secret that allows electric starting via OCDT, ( Over-Running Clutch Drive Tool.)

  • These are our latest engines with the powerful TZ magneto system as opposed to the old SD system. 

  • So, what's SD and TZ ignition?  > go to info. side to find out all the salient details.  

  • Gt5A-ES fits more frames with it's 43mm diameter front mount opening that can be shimmed down to fit a 28mm dia. downtube with the included 7pcs shim kit.   

  • A 7 pcs front mount 1mm tk. Shim package is included.

  • 43mm dia. Front mount has M8 studs.   Spacing is 60mm center to center which allows big downtube clearance. 

  • Rear mount can fit up to 32mm dia. seat posts.

  • Dual Starting:   Pedal start normally or you can use a 20V Cordless 1/2" Drill with the included "OCDT" .

  • ES = Easy Start Cordless Tool starting. OCDT means, "Overrunning Clutch Drive Tool" 

  • OCDT is an extra cost attachment tool we sell that enables handheld electric starting.   Comes in two models; 

  • CW OCDT for Left engine side clockwise magneto nut drive for competitor's China Doll engines.   

  • CCW OCDT for SkyHawk ES Right side Counter Clockwise crankshaft drive which is included with our Gt5A-ES engines.

  • If your engine is in tune a 20V cordless tool with OCDT spins the engine so fast it starts instantly!  

  • OCDT works like a starter drive in a car starter.   When the engine starts the OCDT overruns in the same rotational direction, threfore disengagement is very smooth without any drill twisting that could cause injury.                                                                                           


  • This engine can be started with a 20v Cordless tool as well as pedal started the normal way.  

  • No need to have a high-cost heavy bullet train engine with 12V battery and a ton of headaches with broken pull ropes and failed 12V cheap Chinese starter motors.   

  • The most powerful OCDT starting method is with a modified 1/2" Cordless 20V Impact Tool with soft start but first you must deactivate the 2 flyweight hammers by removing the 4 bolt head and mig spot welding the 2 fly weights in place thus giving a powerful smooth rotation without any hammer effect.  See pic on "How To Weld".   If an impact driver is used without the hammers deactivated you will end up destroying engine bearings and the OCDT too, doing so is not warranty. 

  • Light weight and quick start is the way to go!  

  • Harbor Freight has lowest price for Cordless 20V 1/2" Drills and Impacts.  Watch for their sales adds:

  • Gt5A engine is the most powerful 66cc 47x38 so called 80cc engine by other sellers.

  • Pedal Choppers, in Ft Myers FL says Gt5A has 20% more power than brand X 66cc/69cc.   

  • Has Round exhaust port to fit round exhaust pipe for free flow scavenging.

  • New crankcase and new cylinder design for improved power output.

  • With included shims this engine fits up to 43mm dia. bicycle down tubes.   Ideal for Aluminum frames.  A Dual U Bolt front clamp is available at extra cost.  (Order separately)

  • Consider ordering our HP head that works great with a thin copper gasket which enables higher compression for higher horsepower. 

  • Has hardened dual 8mm dia. front mounting studs.

  • This add is for a Long Block Engine with extra accessories.  Supplied without tank, Carburetor, or Muffler, but we do include a high performance TZ CDI with this engine so you are assured it matches the TZ high performance rotor magnet and coil.

  • Complete engine installation kit available under separate listing. 

  • This engine is ideal for worn out engine replacement or for making a custom DIY installation. 

  • You can use a multi shift kit but pedal starting can be laborious and strenuous hence the real value of OCDT electric start. 

  • Of course, the Bicycle, and Cordless Tools shown in pictures are not included with this long block engine. 

  •   If you are installing this engine on a bike with a downtube smaller than 43mm dia. you will need to use the included 1mm thick half-moon shims to reduce the mount opening to fit your downtube.   ( As of Nov. 15 2020 our 7 pc Shim kit is included with engine. ) 

  • Please know will no longer ship 2 stroke engines to Canada.