Yz400F motor questions


2 replies to this topic
  • cattyompus

Posted October 08, 2007 - 11:14 AM

#1

Hey guys, I have a Yz400F motor in a quad frame and its not stunning. Its not bad, considering it was replacing a XR400 motor but Im looking for some more grunt.

Ive researched a little and found that they make a 417 13.5:1 kit. The kit was about $600 and was a new piston and cylinder.

Also, they sell the 417 piston alone. Im wondering if you can bore the stock cylinder and re nicasyl to accomodate the new piston.

Ive also heard that a 450f cam is a good idea, with the auto decompression and a gain in performance. Can you go with an aftermarket 450 cam with the stock decompression device?



Lots of questions, I know. Im just looking for a good motor setup. I considered just getting rid of the motor, and starting with an electric start yfz450 quad motor also. Im kinda in the research stage now though. I figure adding some cc's and compression, porting and cams would make this a strong motor. Im lookin for somethin in the 50hp range... Let me know what your opinoins are.

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  • grayracer513

Posted October 08, 2007 - 12:25 PM

#2

Ive also heard that a 450f cam is a good idea, with the auto decompression and a gain in performance. Can you go with an aftermarket 450 cam with the stock decompression device?

If you go aftermarket, it's simpler just to get one made for the 426/400 in the first place. Then you won't have to use any modified timing procedures.

You might get 50 hp out of it with enough work, but you'll get more grunt if you start with a bigger engine in the first place

  • Scottcro

Posted October 19, 2007 - 07:05 AM

#3

I put the 426 cam in my '99 WR 400 -- eliminates Comp release, great starting, smoother powerband... best $$$ I've spent on WR 400!!





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