slow 2000 yzf426

Maybe it's just me, maybe I was used to my 1998 yzf400. Either way the power delivery on my 426 just isn't cutting the mustard. To sum up the power band in one word, SLOW! I have had it since it was new, it is bone stock. I am no pro rider but I know slow when I experience it. It is not doggy slow, but it is not what I expected. I know that a lot of people will answer this post with a note about their shoulder popping 426, but mine barely scoots me back on the seat. What could be wrong? It's new, It's never been worked on, I'm at 500' elevation in California. I was expecting great things after coming off the 400f, but have been very disappointed thus far. I recently fixed the problem, but it cost me $7,500.00 and it's orange. Yeah, the new bike rips, but I would still like to fix the blue one w/o trying everything in a trial and error procedure...HELP!!!!

Hey there how's going,I know what you mean I to came off a stock 99 yz400 now have 00 426 and I noticed the same very disapointed 400 ripped.Aparently the ignition curve has been alterted in the 426 to give more torque more drive.I wanted my 400 back didn't like it but have got used to it,scare's the crap out of me at times,it's a beast but I love it.Awhile back I read in magazine that you could buy an adjustable ignition with a bar mounted switch so you could change the igintion curve on the run ie more low down torque or more rev's nothin sweeter than a 426 screaming its lung's out and bouncing off the rev limiter,but alas I cannot remember what magazine it was in.Down here in New Zealand where our dollar ain't worth **** I payed $13500 it now has a bent front disc and rim cracked and weeping stator cover I just keep feeding it tyre's and gas and chain's and sprocket's and brake's and check the oil.This is one hell of a bike just need to soften the suspension a bit and it will be sweet.

Seems like one hell of a long shot...could it be that it has WR cam/valve timing? My racing buddy went from his '99 YZ400 to a '01 YZ426 and said the 400 was stronger from middle to top. I dunno...never rode a 400.

Thinking '00 426 had a slight carb glitch when wicked open quickly. I went from the stock #162 main jet to a #160 and the thing came alive like a monster on steroids. It might possibly be a jetting problem. High performance 4-stoke engines respond well to the proper stoichiometric fuel/air mixture. This is especially true for high compression 4-stroke engines such as the YZ-F's. Just take notice of all the plug fouling problems that so many 426 owners are experiencing. My advice is to go one richer on the main jet and see if it get worse. If it does, go one leaner on your original main jet. The reason for going richer first is to avoid damaging your engine from excess heat generated from a too lean mixture.....assuming that the mixture is overly lean to begin with. Keep a written record of your starting point, jetting changes you make, and the results. Good luck.

426 slower than a 400? I've owned the '99 400, '00 426 and '01 426 and the 426 is much stronger everywhere. The '01 also revs much faster with improved throttle response. Try the jetting and check your plug.

check your valves clearances also this will keep your bike from revving quickly and hitting the rev limiter!



I get my kicks on a 2001' YZ426!

Friendswood, TX

You say your 426 is still new, but my '00 426 clutch started to slip 20 minutes into the first ride. I kept riding it that way for quite some time before the clutch really let go. You can ride this thing in "partial slip" mode for a long time before the problem becomes really noticable. "Doggy" is the best way to describe how it reacts under load with a bad clutch.

Someone also posted about a slow '99 400, and although it could be caused by tight valve clearances (certainly worthwhile checking), it sounds suspiciously like a clutch giving up.

When I replaced the clutch on my 426, the thing went like stink. I could hardly ride it at first, because I wasn't use to the sudden hookup and acceleration.

The clutch may or may not be the problem, just one more thing to think about.

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