Critically Important Engine Information


Additional Options

We strongly recommend getting shipping insurance and / or signature at delivery. We also recommend extra packaging below.

Delivery companies are notorious for mishandling or damaging engines. These protect you regarding your engine being damaged or lost. In the rare event that your engine is lost or destroyed from damage you could lose your entire investment with no recourse.

Shipping Insurance or Signature at Delivery: Click here

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


  • Adjust valves after break-in period.
  • Change oil after break-in period of one one to two tanks of gas depending on the size of your tank.
  • 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.
  • Do not use synthetic oil in GY6 engines until after the break-in period.
  • Install a uni-filter with new engine for longer life and better performance.  If you don't you are guaranteed to be putting dirt into your clean NEW engine.  Stock Chinese air filters do not effective filter air and are the number one engine killer for GY6 engines.
  • Do NOT exceed 60% of full throttle for a one hour break-in period of 1 to 2 gas tanks.  Vary your speed during the break-in so that the engine sees a variety of conditions and helps break it in for a broader range of operation. 
  • Wash and re-oil your uni-filter periodically. If you are riding in dusty environments and the oil on your uni gets overwhelmed with dust the filter will stop working and will past dirt into the carb and engine.  The oil is what traps the dirt.  Once it is loaded with dirt you MUST wash the dirt out and re-oil.

Do's and Don'ts

  • If you have unsupervised children riding the vehcicle please teach them the dos and don'ts.  
  • Let off of the starter key once the engine has started.  Starters and starter clutches damaged from this action are not covered under warranty.
  • Do not continuously hold the starter key for prolonged periods if you are having problems starting. Holding for periods over 5 seconds will damage the starter. Give a few seconds between tries.  Starters and starter clutches damaged from this action are not covered under warranty.
  • Do NOT shift from forward to reverse until the vehicle comes to a complete stop.  Gears damaged from this action are not covered under warranty.

All of our engines come with a one year warranty against defects but you must install a uni-filter.  This ensure clean air to your engine. The warranty does not include abuse of your engine, not changing oil, not using an air filter.  Your Warranty is void if you do not follow the instructions below:

  • You must purchase a uni-filter and uni oil at the time that you purchased your engine or have proof that you had in your possession a new uni-filter and oil at the time of purchase.  Our warranty is void if you do NOT use a uni-filter with this engine.  GY6 stock air filters are notorious for allowing dust and debris into the engine and requiring a rebuild in a few months.
  • Do NOT exceed 60% of full throttle for a one hour break-in period of 1 to 2 gas tanks.  Vary your speed during the break-in so that the engine sees a variety of conditions and helps break it in for a broader range of operation. 
  • Check all vent hoses.  Some engines have plugs and some have the vent hoses taped shut to prevent oil leaks during shipping.  Remove all plugs or taped hoses to prevent from blowing out your cylinder gaskets.
  • Modify your engine without first contacting us and us agreeing the the changes that you are making.

Save Your Box--No Box No Warranty
In the event that you need to send your engine back to us for a warranty issue or another reason save your box.  GY6 engine damage is a huge problem and if you ship without using the box that we shipped to you are almost guaranteed to get engine damage,  Thus we have a no box no warranty policy.

Guaranteed Fit - No returns on engines.
Before ordering please call and speak to our technician if you have any questions regarding fitment.  Please do not return your engine--call us if you ordered the wrong engine without consulting our technician. In the very rare event that there is a warranty issue please see warranty section.

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. 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 even decades--we've seen it many times. Coolers provide a false sense of longevity benefits, and the only proven result is the added risk of unexpected massive failure.

If you are considering purchasing a GY6 engine from eBay, Amazon or any other USA seller you could receive a 125cc engine instead of a 150cc and you would never know it. Since 2006 China has a history of sending 125cc GY6 engines in place of 150cc GY6 engines. The engines look identical from the outside. BDX Performance is the only engine seller in the USA who disassembles and visually inspects engines to ensure that they are 150cc. We unbox and dissemble approximately 50% of every engine shipment that we receive as we convert these into 175cc engines. And we have caught some engines that are GY6 125cc being sold as GY6 150cc--see below. Don't play Russian roulette with your money. Get a guaranteed, verified and certified GY6 engine from BDX. The cylinder on the left is an actual cylinder that we pulled off of a China engine that we purchased as a 57mm GY6 150cc engine and was actually a 52mm GY6 125cc engine.

Delivery Times

Approximately 60% of our engines will ship within 24 hours of your order.  However, we build many of our own engines.  During peak periods these engines may take 1 to 2 weeks and sometimes even longer.  Most sellers today simply have to slap a label on a part made in China. WE ACTUALLY MANUFACTURER STUFF HERE AT BDX PERFORMANCE EMPLOYING AMERICANS. Making stuff takes time and is not as easy as slapping a label on something from China.  If you have an urgent need for an engine, by a specific date, GIVE US A CALL AND LET US KNOW!.  This way we can make adjustments and see how close we can come to meeting your date.  In most cases we will be able to accommodate your date.  


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Read article on how displacement relates to more power:  How big bore kits & strokers work.  TAKE A LOOK AT THIS COMPARISON

Stock GY6 Engine


BDX Performance Engine


We build and test our 175cc big bore engine in our facility in Virginia.  

We disassemble your 150cc engine, bore the case to make it larger so that we can install a 62mm big bore piston and cylinder.  Then we re-assemble and test your engine.

Boring the Case for the 62mm Cylinder and Piston

62mm 175cc Big Bore Kit

Be sure to read the article on how displacement affects your power.