Yerf Dog ATV 150CC GY6 Engine

In stock
Regular price $799.00

GUARANTEED FIT FOR Coolster Reaction 150CC ATV: New GY6 150cc Internal Reverse ATV Engine. Yerf Dog went out of business over a decade ago.  This is NOT the exact engine that originally came in your Yerf Dog but in an ugraded version of the same engine with the same mounting points.  With this engine you shift from forward to reverse using the shifter handle as oppose to a switch on the handlebars.

You can get this same engine with more power as a 175cc engine. 


Read our article on how displacement relates to more power.
How big bore kits & strokers work

To see more on converting this new engine to a 175cc racing engine please see:

175CC racing Engine

Engine is shipped DRY with no oil. Be sure to add 750ml of 10w40 to the crankcase and 120ml of 80w90 to the gearcase before starting.


No returns on engines.
Please do not return your engine. In the very rare event that there is a warranty issue please see warranty section.

What's included:
Everything under the engine's covers and plastics is included and installed, this is a complete unit. Starter, stator, and intake manifold arrive bolted to engine. CVT transmission is fully assembled and cover installed. All transmission components are assembled and cover installed. All drain bolts and internal oil screen are installed. Valve cover installed.

Sold separately:
Carburetor, exhaust, ignition components are all sold separately.

Remember to adjust valves after break-in period..

About Oil Coolers:
Our engines do NOT come with provisions for oil coolers. We've always advised strongly against the use of oil coolers on the GY6, and we do not offer them on our engines. We've seen too many instances where a cooler line bolt vibrated loose, dumping all of the engine oil and causing a massive failure. The perceived benefit isn't worth the risk. Oil coolers on the GY6 solve a problem that doesn't exist. Follow regular maintenance intervals, invest in a UNI Air filter (and keep it oiled), and your new engine will last many years. Coolers provide a false sense of longevity benefits, and the only proven result is the added risk of unexpected massive failure.


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