2007 YZ 450 signs off earlier

9 replies to this topic

Posted March 28, 2010 - 09:07 PM


I've got a bone stock 2007 450. Love the bike, but it doesn't have much top end. Do any other 07 owners have the same feeling? My 06 seemed to pull quite a bit longer on the top end. Does it have to do with the silencer having a smaller diameter hole?:thumbsup::banghead:

  • Family Man

Posted March 29, 2010 - 08:17 PM


The 07 should have more top end, different cam profile.The muffler does fine in the top end. Check your jetting.


Posted March 30, 2010 - 08:24 PM


Would this indicate a lean or rich condition on top? I'm thinking lean like I'm running out of fuel on the top end?? Thanks for any comments.

  • Family Man

Posted March 30, 2010 - 09:21 PM


Is it blubering in the top end? Or popping?

  • Six5

Posted March 30, 2010 - 09:50 PM


My '07 seems fine on top, but I could use a little more grunt down low. And mine is stock except for a Zip Ty carb mod.

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Posted March 31, 2010 - 04:20 PM


It seems like it runs fine, no blubbering or popping up high. It blubbers a lot down low. It just stops pulling sooner than my last 3 yz450's have.

  • grayracer513

Posted March 31, 2010 - 04:25 PM


You might want to check your cam timing.


Posted April 01, 2010 - 04:13 PM


Thanks for all of the advice guys, checked the valves and timing, everything looked really good. I'll try dropping a size on the main jet and see if that helps. I think I'm around a 170 at 4500 ft, probably too rich, the plug was pretty dark and wet.

  • Family Man

Posted April 01, 2010 - 05:11 PM


The plug condition generally dont mean squat on a four stroke. Try adjusting the jetting pilot circuit.

  • qwert321

Posted April 01, 2010 - 06:15 PM


160 is stock for sea level,you stated your bike is stock so you should atleast be at 160 maybe 155-158

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