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Engines and Components› Pistons and Piston Rings

TB Parts

138cc Big Bore Kit

$199.99 $199.00 Save $0.99

SKU: TBW9374

In Stock
In Stock
Ships by Jul 29
Free Shipping
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Advanced — 4+ hours

Description

The TB Parts Big Bore Kit is a 138cc engine upgrade for the Honda CRF125. This kit aims to increase power and fun for your trail bike by offering more power and higher compression. It is designed as a bolt-on upgrade that does not require boring of the engine case.

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

BrandTB Parts
Part NumberTBW9374
CategoryEngines and Components

Buy with Confidence

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.

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