2004 YZ450f question/advice

2 replies to this topic
  • csrozier

Posted March 24, 2015 - 12:59 PM


Hey guys,
Recently traded a 99 cr250 for a 04 450f and I have a question or two. first off my 450 runs great, but after kick starting a few other 450s, mine has compression and it'll hurt your foot kicking it all day long if I'm steadily turning the bike off and back on. I mean it will start right up first or second kick it just seems like it should have a bit more compression because I do not have to use the hot start decompression lever to get the bike started but kicking my buddies yz400f I could stand on the kickstart straight up and down and could not get it to move at all but he had a high compression piston in it. if I was planning to do some upgrading to get more power, what would be the best recommendations for that? I don't want to spend $1,500 tearin the head completely apart and back together and anything crazy I was just thinking of maybe replacing the piston and rings that are in the bike now with a high compression piston. any thoughts or recommendations? Also was the 2004 yz450f a strong year?

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  • grayracer513

Posted March 24, 2015 - 01:15 PM


There is no decompression lever on any YZ450F.  All of them, starting with the '03 model, have automatic decompression built into the cam that reduces the length of time in crankshaft degrees that the compression stroke lasts.  The Hot start lever is a manually controlled air bleed into the carburetor to make the hot engine less prone to flood on restarts immediately following a stall out.

  • 03yzf450-kuke

Posted March 24, 2015 - 03:21 PM


Ya dude your bike is fine just ride it. The 03 and up 450 are way easier to kick than those 400s or 426s.gotta love the auto decomp.

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