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YZ426F Rider

Valve timing problem maybe?

2 posts in this topic

I just installed the Hotcams auto decomp cam in my '02 426 and she fired right up on the second kick. I love not having to deal with the compression release!

I have not ridden it yet but for the two minutes it was running in my garage it sounded great, throttle response was great (even cold), no weird noises...everything seemed hunky-dory. Then I put my hand down by the vent tube where it ends in front of my shifter and I could feel air (exhaust?) pulsing out of it...not just barely, it was definitely pulsing out with the engine revs. The problem is that I actually have never put my hand there while the bike was running so I don't know if it's normal, if it has been doing that for awhile or if it just started doing it. After rides it has been obvious that oil comes out of there while running but it's never been enough to affect my oil level.

So I rechecked my valve clearances again and they are perfectly in spec...is it normal for that much air to move through the breather tube or does this signify that I have a seating or valve timing problem?

With the piston at TDC I have 14 pins between the upper marks on the intake and exhaust cams. The punch marks on the side of the intake cam is lined up flush with the head but on the exhaust cam it seems like it is just slightly below the head. It actually seemed to be lined up better with a 13 pin gap but I have always heard 14 pins and in the diagrams in the manual it appears to be 14 pins. I have never actually paid attention to it before...I've always just made sure the marks were lined up.

Any help would be hugely appreciated!

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UPDATE: I read in a different string that Grayracer says that with the Hotcams cam to just line up the punchmarks and not worry about the pin count like if it were the OEM cam...so I adjusted the position of the exhaust cam to better line up the mark (it's at 13 pins now).

Bike fired up 2nd kick, seems to run great, but the air is still coming out of the breather tube. I did notice that when I bring the bike up off of idle that the air flow coming out of the breather tube pretty much stops...does anybody else's bike do this???

I guess I'll find out tomorrow when I go riding how it all is going to work out. Hopefully fine as I am running a hare scramble on Sunday!

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