05 wr450 cam mod and hard to start

6 replies to this topic
  • sheriffwoody

Posted April 04, 2006 - 08:09 AM


Hi all, I just purchased a 05 WR450 and the original owner cut the grey wire and he just got it back form the shop. They adj valves and move the exhaust cam 1 tooth per original owners request. The bike had trouble starting after getting it back. I bought the bike and then removed the ais, cut the airbbox open and rejetted to TT specs.
It still will not start easily. With the electric starter it turns over plenty fast (new battery) but you have to very very gently crack the throttle slowly to get the rpms up for it to start. If you go to fast it backfires and wont start. It takes 30 seconds + to get it started with the battery running low each time. Adding extra fuel does not help.
I assume it is posible the shop got the valves too tight, but from what i am reading the exhaust cam mod should not be done on an 05? Can someone clarify?
Las Vegas, NV

  • jchantzWR400F

Posted April 04, 2006 - 11:47 AM


Cannot do this mod on the 03 and newer WR's. In order to get YZ timing, you'll have to get a YZ exhaust cam. :thumbsup:


Posted April 04, 2006 - 12:02 PM


Rotating the exhaust cam worked on the earlier WR's but not on the 450's. The autodecompression pin is different on the YZ cam to compensate for the timing difference. If you try to rotate the WR cam the autodecomp will not work properly. You need to either rotate the cam back or if you want the YZ performance install a YZ cam.

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  • farkawi

Posted April 04, 2006 - 07:16 PM


The stock '05 cam can be modified to YZ timing. But NOT by simply rotating the whole camshaft! The sprocket must be pressed off of the cam and the cam re-timed before pressing the sprocket back on. Not many hobbyist mechanic types have the skill to do this properly; which is why you will see the majority voting for YZ or Hot Cams replacement camshafts......It is a whole lot easier to replace a cam than to do the mod on a stock autodecomp cam. Good Luck!

  • MountainMax

Posted May 26, 2006 - 10:59 AM


which is cheaper the yz cam from yamaha or a hotcam? are they the same performance/Lift?

  • byggd

Posted May 26, 2006 - 11:03 AM


which is cheaper the yz cam from yamaha or a hotcam? are they the same performance/Lift?

Not sure about Hot Cams but the TT store has a great price in the O.E cam :ride:

  • MountainMax

Posted May 26, 2006 - 11:14 AM


they do however im in canada, and customs and stuff makes it less worth wile, my dealer will give me 10% off anyhow, Now i just need the part number to order.


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