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Cylinder Works Replacement Cylinder Head Assembly (422-2005HD / CH2005-K01) | Yamaha YZ125

Sale price $145.95

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High-performance replacement cylinder head assembly engineered to restore optimal combustion efficiency and thermal management for high-output two-stroke engines. Manufactured from high-grade cast aluminum with optimized squish band geometry and coolant flow channels to resist detonation, reduce operating temperatures, and withstand the extreme pressures of aggressive racing environments.

Specs & Details

  • Manufacturer Part Number: 422-2005HD
  • Alternative Part Number: Cylinder Works CH2005-K01
  • Component Type: Replacement Cylinder Head Assembly
  • Material & Construction: High-grade cast aluminum engineered to strict OEM thermal and structural tolerances
  • Compatibility: Direct bolt-on replacement for stock cylinder configurations

TSO Garage Note

A reliable, cost-effective replacement cylinder head for modern aluminum-frame Yamaha 125s. Whether you're rebuilding after a detonation failure or refreshing a high-hour race engine with compromised squish bands, this casting restores proper combustion chamber geometry and cooling efficiency without the high cost of an OEM assembly.

Compatibility

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Customer Reviews

Overall rating: 4.9 / 5 from 66 reviews.

Customer photo review of 1987-2004 Kawasaki KX500 Shift Fork Kit

Shipping was fast, the product is great! When you could still buy the shift forks from Kawasaki they came out of spec :-( These are in spec and far better quality than Kawi's forks. They are in the bike and vastly improved the shifting on this KX500 BEAST!!! Thanks Luke!

1987-2004 Kawasaki KX500 Shift Fork Kit

Customer photo review of 2017-2025 Honda CRF450r/CRF250r Billet Gas Cap

Unfortunately, the gas cap got scratched during shipping, but after a few friendly emails, the problem was resolved perfectly for both sides. Friendly service, quick solutions, absolutely reliable Top-notch shop👍

2017-2025 Honda CRF450r/CRF250r Billet Gas Cap

Customer photo review of 1988-2004 KX500 Billet Engine Cases

Amazing!!! Luke is so helpful. These cases are amazing and a direct fit of my old cases. All parts are equally made and not one is below my standards

1988-2004 KX500 Billet Engine Cases

The best machined pieces I have ever seen. I have wanted a two piece KX500 billet side cover for a long time and can't wait to install it. So trick!

1986-2004 KX500 Two-Piece Billet Side Cover

Very quick shipping, and super pleased with the quality of this stator cover! The anodized black blends nicely with the satin black powder coat on my KX500 engine.

1983+ KX500 Billet Stator Cover- Kawasaki Logo

Quality parts!!! Very happy with what I received for the money!! Fit and finish is top tier. Also happy to support a company who is helping keep these two strokes alive! I will be back for more parts soon!

Billet Rear Silencer Bracket | KX500 & KX250

Bearings were a perfect fit. A couple of shaft bearings were on back order, which I reicieved shortly after a majority of my orders arrived. Quality of everything is immaculate I would certainly do business with Luke again. I honestly wish I could have purchased the billet cases for my kx500af build after seeing the precision on the covers and head. Highly recommend TSO

1986-2004 Kawasaki KX500 Complete Engine Bearing Kit

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