We have developed a bolt-in engine package for a GY6 reverse engine for your external reverse buggy such as:

Get rid of that gear box. Many people have struggled adjusting it for years.

MODIFICATIONS: In order for this engine to work on your Yerf Dog Spiderbox you will need the following:

You have to make changes to your axle. Your axle sprocket is in the wrong location and cannot space over the sprocket in that direction without lathing, cutting the weld loose and re-welding the sprocket hub in the new location. You can do this or send to us and we cut it loose for you click here. It is best for you to re-weld since you can get the alignment exact with your engine sprocket. We will re-weld if you desire but we will bias the axle sprocket hub towards the brake hub on the axle and you can shim with a few washers, to get exact alignment. It is best to use 5/16th grade 8 bolts. You can shim the axle sprocket or the engine sprocket. The other option is to get a Yerf Dog Spiderbox Heavyduty Axle Kit: This heavy duty axle also fixes the Yerf Dog Spiderbox breaking axle problem. If you are getting the 175cc, 184cc or 232cc engines we recommend the heavy duty axle.
Adapter kit for the Internal Reverse Engine. Includes everything you need adapt the internal reverse engine for your Yerf Dog or Crossfire 150 Click here.

Engine 1: 150cc Standard stock GY6 Engine with Internal Reverse .
Engine 2: 175cc GY6 Engine with Internal Reverse. This engine comes with the 62mm big bore cylinder and piston kit pictured below installed in a bored out case.
Engine 3: 184cc GY6 Engine with Internal Reverse and stock transmission--GUARANTEED BOLT-ON FIT. 62mm big bore cylinder and piston kit pictured below installed in a bored out case and a 3.0mm high performance stroker crank. Recommend performance transmission.
Engine 4: 232cc GY6 Engine with internal reverse and stock transmission -- GUARANTEED BOLT-ON FIT with kit. This engine comes with a 67mm big bore cylinder and piston and an 8.0mm high performance stroker crank. Call before ordering.

YOU HAVE SIX POWER PERFORMANCE OPTIONS

Option 1: American made high performance Uni-Filter air filter ensures clean air to your engine and long life. See Details. Your one year new engine warranty applies only if a new uni-filter is purchased with this engine.

UNI FILTER ASSEMBLE, OIL AND KIT

Option 2: BDX High Performance Racing Transmission and Gates Powerlink Belt: See details. Regular price $249 - Now $99 when purchasing an engine.

Option 3: The BDX A12 Cam Shaft changes the power profile of your GY6 engine to provide the optimal balance for both low end grunt and top end speed.

Option 4: 11 Pole Stator, rectifier and harness adapter. Get more power to run your lights and other accessories.--Click Here. The engine comes stock with an 8 pole stator.
Option 5: Performance Exhaust: You can get the BDX performance exhaust for any of the engines above for an estimated 10% to 15% increase in raw power--see details here.

Option 6: PowerPak: The PowerPak includes all of the other options above, with the exception of the 11 pole stator IClick here

Internal options or other components that you purchase will be installed into your engine (except A12 CS in stock engines).

ADDITIONAL IMPORTANT OPTIONS

Shipping Insurance: We strongly recommend getting shipping insurance. Also see extra packing below.. Click here for shipping insurance.

Double Boxing and Double Padding Your Engine: With this option we double box your engine in a second sturdy box and add extra 1 to 2 inches of styrofoam for extra protection. Click here for double boxing.