yz400f low lw end power high upper end power


5 replies to this topic
  • fordman06gt

Posted July 15, 2007 - 05:42 PM

#1

I just purchased a 98 yz400f, it seems to lack low end torque and power, once its in the rrs its fine. I rode a 04 wr450 and the wr450 has much much more power on the low end. Is the power difference from the yz 400 that much less than a wr450. The yz400 doesn't seem to have much stuff. the engine is 6 months old built by a yamaha dealer so the compression and condition is near new. I am not sure if I should sell the yz 400 and go to a 450.
What is the stock sprocket size? I know it has a 450 pipe on it, other then that I don't know if any other mods are done, but I don't know, this is my 1st 4 stroke, my last bike was a 2000 cr500.

  • Birdy426

Posted July 15, 2007 - 07:05 PM

#2

You might try changing the exhaust cam timing to WR spec and see if that is more to your liking...

  • Alternative

Posted July 16, 2007 - 02:51 AM

#3

Stock sprockets are 14/50 I think. You may want to try re-jetting the carb, might be a bit lean on the bottom end, does it splutter at all? Do a search on here and you'll find all the info. you need to jet it properly.

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  • SXP

Posted July 16, 2007 - 08:37 AM

#4

I just purchased a 98 yz400f, it seems to lack low end torque and power, once its in the rrs its fine. I rode a 04 wr450 and the wr450 has much much more power on the low end. Is the power difference from the yz 400 that much less than a wr450. The yz400 doesn't seem to have much stuff. the engine is 6 months old built by a yamaha dealer so the compression and condition is near new. I am not sure if I should sell the yz 400 and go to a 450.
What is the stock sprocket size? I know it has a 450 pipe on it, other then that I don't know if any other mods are done, but I don't know, this is my 1st 4 stroke, my last bike was a 2000 cr500.


I notice the same thing between my 400s and 450. The 450 has a longer stroke which gives you more low end grunt.

  • fordman06gt

Posted July 19, 2007 - 09:17 PM

#5

Do you know what way you move the exhaust cam for wr timing? I would think counterclockwise????? is that correct?

  • ender_swift

Posted July 19, 2007 - 09:19 PM

#6

Just gear it down a bit. But it would depend on what type on riding the previous owner did, and what you plan on doing.




 
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