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Yamaha YZ250 M-Spec Bolt-On Big Bore Cylinder Kit

M-Spec Bolt-On Kits are new OEM replacement cylinders modified with our proprietary Nickel Silicon Carbide (NSC) cylinder bore plating process and perfectly matched with a high compression standard bore or big bore piston and Cometic gasket kit. These kits typically ship within 24 hours with no wait ready to install. Although there is no core charge or cylinder exchange required, core credits are available for specific models if your current cylinder is in acceptable condition.

***M-Spec 2-Stroke Big Bore Kits and Service Big Bore Kits are ported for your riding style and require modifications to your power valve and cylinder head. Some 105cc, 107cc, 144cc and 295cc kits require case modifications. These additional modifications are included in the price. You are required to send in necessary parts for modifications.***
Pricing: $1,199.95



Fits all Yamaha YZ250 years 1999 - Current Models
Part # MK220BB
OEM Bore Size 66.4mm
M-Spec Bore Size 72mm (+5.6mm)
M-Spec Displacement 295cc


  • 23430086
  • 23430086
  • New

Shipping Information

  • Item Requires Shipping
  • 6.0 lbs.
  • W6.0000” x H6.0000” x L6.0000”

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