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Honda CRF, Kawasaki KXF, Suzuki RMZ, Yamaha YZF 2004-2008
2007 AMA Rules force 250F riders to race against more powerful 250 two-strokes. Equalize your advantage with a Forward Motion Big Bore Kit!
Our 262cc big bore kits include a new OEM cylinder that is big bored and plated with Nickel-Composite's Nickel-Composite plating, plus we include a complete Wiseco piston assembly and gasket kit. The ring end gap is preset and the rings are installed and aligned on the piston. The 262cc kits do not require special modifications to the crankcase or the cylinder head. These kits are ready to bolt on and you don't need to send your stock cylinder back for an exchange. The pistons are designed for a slightly higher compression ratio (less than 1 point) but you need to run race gas, just super-unleaded premium. Switching to race gas will yield better throttle response, especially a brand blended with the maximum allowable amount of MTBE. The power difference from a 262cc kit gives more of everything over stock with no discernable difference in sound. Because these cylinders are new OEM parts and don't have any brandings or markings, they look just like a stock 250. Normally the OEM cylinder plating is very soft in comparison to Nickel-Composite's plating. A stocker will last about 50 engine hours before a significant ring ridge wears near the top of the cylinder and causes the engine to lose significant power. Our testing shows that a plated cylinder with a Wiseco forged piston lasts about 100 engine hours, that's about two moderate racing seasons. If your 250F has at least one season on it, the top end probably needs to be rebuilt before the piston skirt breaks. Our 262cc kits are an inexpensive way to get more power and reliability for the money.
The 290cc kits include an aftermarket cylinder made by either Athena or Vertex. The Athena kits are marked with an embossed logo and the Vertex cylinders look original and have no markings. Generally speaking the 290s produce more low to mid-range so to get a wider powerband you need to buy other aftermarket accessories like a #2 Hot Cam (mid to top end) and some performance cylinder head work like high flow valves, porting, and a multi-angle valve job. The CRF290 Vertex kit requires total engine disassembly and crankcase clearance mods to accept the larger diameter cylinder skirt. Typical additional items needed to do the installation vary with engine wear, but you would at least need a bottom end gasket and seal kit. The big bore includes all the top end gaskets. A hand held die grinder is the best machine tool for accomplishing the grinding task and the Vertex base gasket serves as a marking template.
262cc Big Bore Kit
Price: $650
Includes new big bore cylinder, piston and gasket kits and shipping in the USA.
Type the year, make, and model of your bike
262cc Big Bore Kit (International orders) -
Price: $675
Type the year, make, and model of your bike
290cc Big Bore Kit
Price: $695
Includes new big bore cylinder, piston and gasket kits and shipping in the USA.
Type the year, make, and model of your bike
290cc Big Bore Kit (International orders)
Price: $745
Type the year, make, and model of your bike
SPARE PISTONS & GASKET KITS 262-290cc CRF, KXF, RMZ, YZF
These kits include piston, pin, rings, clips, and all the top end gaskets, made by Wiseco and Athena. The price is $250 and includes shipping in the USA.
International shipping cost is $25 extra.
262cc Piston and Gasket kit
Price: $250
Type the year, make, and model of your bike
262cc Piston and Gasket kit (International orders)
Price: $275
290cc Piston and Gasket kit
Price: $250
Type the year, make, and model of your bike
290cc Piston and Gasket kit (International orders)
Price: $275
Type the year, make, and model of your bike
Telephone Orders Call 1-630-825-5645
Email: ericgorr@hotmail.com