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About Fast_Yamaha

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  1. I am going to build a Velocity Stack Air Filter Adapter something like K&N builds, for my 1998 WR400F. Will I have to rejet it for this mod? K&N Velocity Stack Air Filter Adapter Lightweight Nylon 6/6 Construction, Fits 41MM Keihin CR Flat Slide Carbs. 53mm Long - Uses any 2-7/16" Flange K&N Part # 85-3000 http://knfilters.com/psadapter.htm
  2. Fast_Yamaha

    Changing a 400 to a 426

    In stock size the 400 has a 92mm piston with a 18mm wrist pin and the 426 has a 95mm piston with a 19mm wrist pin. You can buy a 400 piston that is 94 mm oversize piston with the correct size wrist pin. Is there any way I can buy the 94mm piston and put 426 rings on it to fit the 426 bore or will there be to much slap with the piston being 1mm smaller. My bike needs a rebuild and I can get the cylinder for next to nothing. I need all the help I can get. Thanks
  3. I own a 1998 YZ 400F and have rode my friends YZ 426F and like it a lot more than my 400. I was asking around to see if I could change the piston and bore to accept the 426 piston. Will the 400 rod fit the 426 piston, or do I have to split the case and change the rod? Thanks for your help.