M-Spec Big Bore Kits

Almost 20 years of increasing the displacement of internal combustion engines has made Millennium Technologies the leader in big bore kit technology. We offer complete, fully developed big bore kits for a huge variety of powersports applications including 2-Stroke and 4-Stroke off-road bikes, sport bikes, ATV/UTV, snowmobile, and watercraft.

M-Spec Big Bore Service Kit

The M-Spec Big Bore Service Kit is designed to work with your specific vehicle and comes with a complete suite for modifications of your cylinder and perfectly matched pistons, rings, and top end gasket kit.

M-Spec Complete Big Bore Kits

To reduce down time, we offer select M-Spec Complete Big Bore Kits from our core cylinder inventory. If a M-Spec Complete Big Bore Kit is available for your model, we can immediately ship a complete big bore kit with modified cylinder, pistons, rings, and gaskets with a core charge. When we receive your acceptable core cylinder we credit the core charge back to your card. This will greatly reduce potential down time. Please call 888-779-6885 for core availability.

Note: When doing a 2-stroke big bore kit, you MUST send in your head and complete power valve. If you do not send in your head and complete power valve, it will cause a delay in your order and your turn time will be pushed back.

Select your year and model from the drop-down lists. If your vehicle is not listed in our vehicle finder, please contact us at 1-888-779-6885 or info@millennium-tech.net and we will be happy to help find a solution.


2 & 4-Stroke Big Bore Services Include:

  • Cleaning and disassembly
  • Inspection and measurement
  • Overbore service
  • Re-plating with our proprietary nickel silicon carbide composite process and diamond finish honing
  • Piston and gaskets
  • LIFETIME warranty on the plating

2-Stroke Service Also Includes:

  • Professional cylinder porting.
  • Head resurfacing, squish, bowl machining, and polishing.
  • Power valve service with assembly and timing, ready for installation!

Start your service order now with our Service Order Form.





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