2007 YZ 450 signs off earlier

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:

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

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.

Is it blubering in the top end? Or popping?

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.

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.

You might want to check your cam timing.

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.

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

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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