This service is for 1997 - 2018 YZ 125 MOTORCYCLE CYLINDER Big bore .

Cylinder sleeve is installed then Overbored +2mm to 56 mm. Bore NOW 134cc. 

Use a 56 mm Wiseco Piston on this 134cc Cylinder

Send your 56mm piston, remove power valve & studs

Power Valves Must Be Modified/ Recessed 1 mm to prevent Piston Damage!

Head must be  Re-chamfer to work with the Big Bore piston set up to your octane requirements.

Crankshaft -No crank modification required.

Crankcase - No crankcase modification required.


We can Precision machined your powervalve to match big bore ports ( @ extra cost) 

This kit requires you to send us your cylinder, head.



YZ-134 Big Bore Jug ( 1997 - 2018)

Deck Cylinder head
  • Note: Product images only reflect class of products. If in doubt ask before purchasing. Our cylinder sleeves are made from chrome-moly alloy. Our Ports are machined with close tolerance and shapes allowing easy of installation and greatly reduce the need for additional porting after installation.



Thanks for visiting our site. We look forward to assist you with all of your motorcycle cylinder service request.

*We will be adding a full cnc service department in the near future.


Call or text us @ : 1-281-516-8917

Email :

Shipping Address:

Accurate Cylinder & Sleeve Works

24230 Kuykendahl Rd

Ste 310 #148, Tomball TX 77375

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