my wr has no power...(needs rebuild?)

i was hoping to get some advice....you guys seem to have alot of good knowledge so... here goes....

i just got into mx bikes in july...(have been racing downhill mtn. bikes for years) and i got a 01 wr for 1700.00 and it was great to learn on (mostly trail riding) then i found a great deal on a old colorado powersports race bike , a 98 yz 400 for 900.00 it has a 426 topend on it..and it rips it's really quick , and after riding it at the track alot(it's snowy in the mtns now...) the wr feels like a dud....and not just cuase it's a wr. there may be somthing wrong with it. i was going to do the free mods and they were all done. bk carb....throttle stop, grey wire....

so the problem is the wr is plated has a headlight, wired brake light...and the yz is way more fun to ride....

the wr wont wheelie at all and the yz wheelies on accident...

also the yz is pretty hard to kick it over and the wr is pretty easy to kick

does the wr need a new top end?

any way they are both old bikes...should i trade top ends, seems like alot of work.... or rebuild the wr.... i'm stuck...

First, run a compression check on both bikes and compare the numbers. That will give you kind of a general idea if the WR is in really worse shape than the YZF. Remember, the WR cam timing is such that the power is really mellow comparred to the YZ. Are you sure that's not what you're feeling? You might try timing the WR cam to YZ spec and see if that wakes it up. Of course, it just may be time for a rebuild of the WR. If it were me and I had to rebuild, I'd go a Luke's Racing 444 kit on it and at least an autodecomp YZ exhaust cam, if not a set of hotcams. I wold also take a real close look at teh condition of the head, valves, and seats. Do a leak down test before you tear it apart, maybe...

i have a cheapo checker auto parts compression tester do i need and adaptor to test the head on my bike? also are there any threads on how to do a leakdown test i really dont know what it is...i mechanically inclined just never worked on bikes...

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