Got YZ cams on your 07'? With what exhaust?


22 replies to this topic
  • beezer

Posted June 02, 2008 - 08:52 AM

#21

The Dynojet jets are different than Kehin jets and numbered differently I think.

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  • SJMC_DON

Posted June 02, 2008 - 09:52 AM

#22

I am going on record as stating that I am not entirely happy with my decision to go with the YZ cams -

First and foremost, the bike will not start with the e-start despite all my efforts to make sure everything is perfect with cam timing, valve clearances and jetting. I e-mailed Hotcams and they said the OEM YZ exh cam will just dump to much compression due to the taler de-comp pin:thumbsdn:

I still don't have my jetting right, I need a dyno and O2 sensor I think to get it all dialed but it's definitely not right. The bike failed to kick start on my start yesterday... my class was 3 turns into our GP before the thing fired off :thumbsup:

The gain in performance is noticeable and I am sure measurable on a dyno report but IMHO not worth the trade off or sacrifices I have made to try and make it work. The WR was winning races and beating YZ's in my off road series with the stock cams:excuseme: I failed to remember the best advice my father gave me... "if it ain't broke, don't fix it".

I was speaking with a guy that owns and operates a NW suspension and engine performance company this weekend, he also races a WR450F. He explained to me, and I have heard this here on TT before, that the performance gains are going to come from the YZ intake cam and a higher compression piston. He also told me that there will be no ill effect to running the stock WR exh cam with the YZ intake cam. He also said that while he is still running the WR cams, his plan is to install the OEM 06' YZ intake cams on his bikes. So.... I am going to put the stock exh cam in this week and report back.

I know a lot of you are have had good luck with this swap and are happy you made the move so consider my opinions just those of one rider :ride:

  • SXP

Posted June 02, 2008 - 12:08 PM

#23

I know a lot of you are have had good luck with this swap and are happy you made the move so consider my opinions just those of one rider :thumbsup:


Don - Frankly, especially in light of the fact you race, and starts are ever so important, I was very surprised when I read of your cam swap experiment. My recollection from hanging around this forum for the past couple of years has been that the YZ cam swap is an e-starting disaster. I've read of very few positive experiences (in the e-starting department) begining with the 03 model year and on. My neighbor is a good example: swapped exhaust cams on his 03 WR about a month after he got his bike and could never consistently start the bike ever since. He completely fryed the original starter from all the excessive cranking. He recently returned everything to stock (with a new starter) before selling the bike, and that thing would then e-start at the mere thought of it.

Your Dad's advice is/was good:prof:




 
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