rockin KDX, stoopid subvalves.....

julien_d

Member
Oct 28, 2008
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Well, aside from the carnage it was a proud day for the trials tire equipped 89 saturday. We went through some really technical single track stuff at Brown. Lots of boulder hopping, rock face climbs, muddy roots, sink holes, and some of the trickiest sections I've ever ridden. I was riding with several guys who I consider much better riders than myself, however, I consistently wheeled past them as the spun and cursed up the rocky slick hill climbs. One of my buddies on the yz450f said I should be in a commercial for KDX. This right after he said, "maybe I could make it up that if I was a trials rider like you!". Another friend on a 200 EXC is going to pick up a MT43 after watching me ride through some of that stuff. He was full of questions when we got back to the truck. There were 7 of us out. One of my favorite rides yet, great stuff....


Anyway, throughout the day the KDX ran great, but lacked the top end I'm use to. Not a big deal since I didn't have much occasion to get out of 2nd, much less wind out third. I pulled the RH KIPS cover when I got home and noticed that the rod was extending with revs as it should. I disconnected the arm and could just pull the rod in and out with little to no resistance. So I yanked the pipe off and checked the valve operation. LH subvalve is about halfway between open/closed, RH is closed, and neither move when pulling the rod by hand. The mainvalve still works properly. I guess I'll yank the jug this evening and see what went wrong where. Everything was spotless when I cleaned/reassembled the top end about a month ago. This is the 2nd trip out since then.

Anyway, I was still awfully proud of myself and my bike on saturday. I was making guys twice as good as me look like fools trying to get up through some of those sections. Truly fun stuff!!

I'll post back with details of the powervalve carnage....


J.
 

julien_d

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Oct 28, 2008
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Ahhh... here we go.

CLICK ME



cellphone pic, btw. The rod looks fine, and the main valve is fine as well. You can see on the bottom of the RH valve how small the lower um.. stem has gotten. I'd call that worn out.
 

dansavage

Member
Jul 14, 2008
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brown mountain is a fine place that will wear on even the best of riders.... That's my next riding trip when my buddy returns from vacation. Looks like you have your valve opportunity under control!!!
 

ibishop

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Nov 27, 2008
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julien_d said:
CLICK ME

cellphone pic, btw. The rod looks fine, and the main valve is fine as well. You can see on the bottom of the RH valve how small the lower um.. stem has gotten. I'd call that worn out.

Wow, that's crazy! Those broke/wore in exactly the same way mine did!

When you replace them, consider doing the punch/rebore trick to make the new stems fit the lower bushing more exactly.

Ian
 

julien_d

Member
Oct 28, 2008
1,788
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ibishop said:
Wow, that's crazy! Those broke/wore in exactly the same way mine did!

When you replace them, consider doing the punch/rebore trick to make the new stems fit the lower bushing more exactly.

Ian

Already planned on it. I've also considered drilling the little hole in the bottom of the bore out to 12mm and finding a 12x6mm brass bushing to press in there. Not sure if it would help or hurt....
 
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