Engines and Components› Pistons and Piston Rings

MotorGenic

330cc Big Bore Cylinder Piston Gasket Kit

$194.55

SKU: M587-A025

Special Order
Special Order
Ships in 4–6 weeks
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Advanced — 4+ hours

Overview

The MotorGenic Big Bore Cylinder Piston Gasket Kit is a top-end rebuild kit designed to increase engine displacement to 330cc. It features an 80mm bore size and a 65.50mm stroke, resulting in a 11:1 compression ratio. The kit includes a forged aluminum piston with a Molybdenium Teflon coated skirt for reduced friction and wear, and an anodized dome for heat resistance. Performance gaskets are included for durability and reliability.
Show original supplier description
The MotorGenic 330cc Big Bore Cylinder Piston Gasket Kit is a comprehensive top-end rebuild solution engineered to enhance the performance of your Honda Sportrax TRX300EX. This kit upgrades your engine's displacement to 330cc with an 80mm bore and a 65.50mm stroke, achieving an 11:1 compression ratio. The piston dome is anodized for superior heat resistance. High-performance gaskets are utilized throughout the kit, ensuring increased durability and greater reliability for your engine's top end. The package contains all necessary parts to rebuild the top end: a cylinder, 80mm piston, piston rings, wristpin, circlips, cylinder head gasket, cylinder base gasket, and chain tensioner gasket. The piston rings' end gaps are pre-checked for proper sizing. This kit is specifically designed to fit the Honda Sportrax TRX300EX 2x4 models manufactured between 1993 and 2008. It replaces original part numbers such as Cylinder: 12100-HM3-L00, 12100-HM3-670; Piston: 13101-HM3-670; and various gasket part numbers.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

Fitment Guaranteed

Don’t gamble
on fit.

Log your build in the MOTORMIA app and we’ll guarantee this part fits your exact setup — or your money back, return shipping covered.

Available on iOS & Android

Specifications

BrandMotorGenic
Part NumberM587-A025
CategoryEngines and Components
5,000+ Trusted brands
1M+ Enthusiasts
5M+ Parts sold
(760) 282-4645 hello@motormia.co

Buy with Confidence

Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

View Full Return Policy

Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

View Full Shipping Policy