KX Riders
Maintenance & Technical => KX500 Original => Topic started by: gumby_55 on May 11, 2005, 08:08:36 PM
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HI, I have been having alot trouble with my powervalve lately, and was hoping to get some advice. Starting a while ago it was no longer opening, and I found that the parts were siezed due to carbon build up. I took everything apart, cleaned it up really good, and put it back together. It still doesn't open. It makes my bike seem extremely slow on top, and is driving me nuts. I took the plastic boot off of the actuating arm, and revved the motor to see if it did anything. Nothing happened. With the linkage not connected, the actuating arm moves very easily, and with the pipe off, I can see that the valves open properly. When I hook up the linkage, and pull out the actuating arm and let go it springs back into place like it should. My question is, what should I look for? So far the best I can come up with is to replace the spring, needle bearings, and possibly the gear on the ball bearing doohicky thing inside the clutch cover. (I also dismantled that and cleaned it too.) I'm lost, and can't think of anything else to do, or look for. Thanks for your help!
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Gumby_55,
I think you have done all the right stuff.
Have you tried to remove the collar on the actuating rod and see if the arm moves when you rew the engine (without having to pull the rod). If it does not, the problem is somewhere under the clutch cover. Maybe it does work but you haven't reached the right RPM?
//John
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Ok, today I had a friend help me, and we revved it a little higher than last time. It IS opening. I rode it, and the power still feels very weak on the high end. I can barely pull on my buddies 125. When I bought the bike it was a basket case, and it seems like I can't get this problem solved. Could it be a jetting problem, or maybe I have overlooked something. It lacks that high end hit that 500's are notorious for. The bottom end power feels good but the top is flat. thanks
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How old is the piston?
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You should be able to pull your buddies 125 way before the kips opens. Keep in mind the kx500 does not have the dramatic powerband hit most 125's do. It just makes power all the way thru the throttle. read your plug and run a compression check. my 125 feels way more dramatic, but the 500 is deceiving, as you realize a small amount of throttle has just sent you 500ft down the road.
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Oops, I meant 250. My brother has a 125. If I could barely pull on a 125 I would get a different bike. lol. The piston has about 15 hours on it. I'll have to use the loan a tool service at Auto-Zone to get a comp. tester so I can check it anyways. I was fiddling with the bike again, and the kicker doesn't seem like it has as much resistance as it did before I rebuilt the top end. Although it did fire up on the first kick. Could I have low compression because of a screwup on my behalf? Or maybe the rings didn't seat properly? Thanks again for the replies.