'02 WR426 Issues?
Posted August 14, 2003 - 02:25 PM
I am a long time KTM rider. I need a second bike for numerous reasons. I have always liked the Yamaha thumpers, so I am going to buy one (I think). I have a line on a 2002 WR426 that I can get for $2500. It is in incredible condition, with extras, like O-ring, Ironman sprockets, Scott's ready, exc. It has a popping or hesitating during acceleration. It is YZ timed, has a new black box, and the carb has been gone through numerous times. It had this problem even before the YZ timing.
Here are my series of questions:
- did the '02-WR have any reported CAM problems (mis-ground)
- Any common electrical problems
- Any Valve train issues
- A few KTMs had the bottom part of the slide installed backwards that created issues - any Yamahas have this problem.
I do not want to become a frustrated Yamaha owner after years of owning KTM's, but I have always liked them and HAVE to give it a try.
Posted August 14, 2003 - 03:36 PM
Posted August 14, 2003 - 04:02 PM
Posted August 14, 2003 - 08:39 PM
Posted August 14, 2003 - 08:42 PM
Posted August 15, 2003 - 04:13 AM
I am probably going to go ahead and buy the bike anyway. I am willing to take the challenge, and it is an awesome deal. I just thought if a similar problem had been experienced by one or two of the thousands here it would save me MANY steps in diagnosis.
Posted August 15, 2003 - 04:30 AM
Posted August 15, 2003 - 05:04 AM
Posted August 26, 2003 - 08:23 PM
I first checked the slide plate to make sure it was not installed upside down like some KTM's last year. I then installed a richer needle (OCEMP #3) - simple, quick try. I cold fouled the spark plug within 30 seconds. So, back to the drawing board. I decided just to remove the carb and check out the baseline settings and go from there. Stock needle (DRR #3) 45 pilot, 155 main, BK squirt ~ 2.5 seconds, mixture screw at 2 turns. I then realize I probably went the wrong direction with the needle clip position, and also quickly discerned the jetting was actually somewhat backwards. I change the needle (EMP) clip to #5, I take the mixture to 1 1/2 turns, I install a 38 pilot, 158 main, and time the BK squirt to what looks to be just under one second. Also one other interesting find. The spark plug was gapped like a KTM = .24. I installed a NEW plug at .30. I put in fresh gas, turn on the petcock, pull out the choke, give one full turn with the throttle, go one click past TDC with the kick starter, no luck. Once more - one click past TDC bring the kick starter back to the top, like before, and she purrs like a kitten (except I had the idle turned to high). I give the WR once (or four times) up the street and back, Man does this bike run. No surging, no back firing, just one heck of a pull. The head pipe did glow red when I was letting it idle and checking for any bog or backfire, but I hear that this is a normal occurrence with these bikes.
Thanks for all the responses. I just wanted to let everyone know the findings.