The stock Yamaha YZ250 cylinder has a lot of tuning potential.

Dear MXperts,
I have a 2004 YZ250 and I’m interested in turning it unto a YZ270, what are some of my options?

There are YZ250 big-bore kits available from L.A. Sleeve and Athena that offer a full range of options, but we would suggest sending your old stock cylinder to PowerSeal USA. They not only specialize in boring and re-plating cylinders, they can provide the big-bore piston size of your choice. They are experts at Nickel Silicon Carbide plating. By plating your big-bore cylinder instead of sleeving it, you get superior lubrication, better heat transfer and greater wear resistance. The fit and finish of a PowerSeal USA cylinder is superior to OEM cylinders, and re-plating is far less expensive than purchasing a new cylinder (especially if your old cylinder has already been ported to your liking). For more information about PowerSeal’s big YZ250 option, call (866) 845-1531 or go to


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