Just bought a 2000 YZ426F...

First of all, hi to everyone. I've never been to this forum before, but it looks like the right place to be for a guy who has a couple of questions. If these questions have been asked a billion times, please direct me to the appropriate thread.

First a little history:

I bought a 2000 YZ426F recently and it is totally stock as far as I know. It's been in storage for a couple of years actually, and before that an older motocross racer/mechanic owned it and he wasn't a hard racer by any measure. I think the bike saw one season. He was apparently very meticulous about maintenance. Needless to say, the bike appears to be in great shape, and rides nicely.

Anyhoo, I've ridden it for a couple of days now and immediately have a couple questions. My style of riding is mostly just Sunday-afternoon-with-the-buddies type of stuff. We go hill climbing, rip up the local sand pits, cruise along through fields and do some trail riding.

One thing I've noticed is this: There's plenty of power when you crack the throttle wide open in all gears, no hesitation or wavering performance. But as I get close to the top end of each gear, the power seems to waver and won't return until I either shift to the next gear or slow down and then crack the throttle open again. Admittedly, I like to get the most out of each gear on straight runs, and I would have to say that I must be getting close to what I would consider the redline threshold(but I only have my ears and the sound of the engine to tell me that). I know it's not over revving. Is this the so called "rev limiter" cutting in, or could it be something else?

The other thing is this: I know this bike was meant to be on a track as a motocross machine, and I knew it would have limitations as far as low speed trail riding was concerned, but I never knew how limited it really was.

My friends and I do a mix of hill climbing, sand pit goofing around sessions, and straight open cruising. However, we also ride through some really winding, rutty trails in wooded areas and I have stalled this bike more in the last two days than I've stalled any other bike I've ridden in my entire riding history! You can not putter along switchback trails in first gear without stalling or riding the clutch all the time. At very low speeds I get a "clacking" noise from the chain when it's on the verge of stalling.

I've heard of several solutions from friends and other people on this board. Stuff like putting on a one tooth smaller front sprocket, or a 12 oz. weight addition to the flywheel, or even the addition of some kind of clutch modification. What's the most effective modification to allow me to ride slow over bumpy, twisted and cramped backwoods trails without sacrificing too much power/acceleration/speed in other situations What do these mods cost?

I ride a 2000 426 just like you and ride the exact same terrain you describe, and i run a 13/48 combo and never stall in the tight rutty twisty stuff, or ever for that matter. Remeber dropping 1 tooth in the front is = to adding 3 in the back. I have heard of the flywheel weight thing and the different clutch and what not, but for me the right gearing is all I needed and it performs excellent.

Welcome to TT the great place to be. I have a 2000 as well, the first thing I will say is visit motoman393.thumpertalk.com

Look at the Tech Articles it has tons of free mods and setup tricks for the 2000. Second the GBmod is one of the best mods the 2000 can have. You can see my write up on the GBmod here GBmod Explained

Next you will want to look at the clutch fix for the 2000. There are two things you can do 1 is the Rekluse Zstart and the other is a $100 fix. The 2000 is notorious for a chatter clutch. Here is the link to the $100 clutch fix 2000 Clutch Fix and here is a write up I did on the Rekluse Zstart Auto Clutch Zstart Review

Out of the Box the 2000 has some jetting issues, in 2001 the fixed the low to mid with a new needle an EPJ standard needle from the 2001 is recommended even with the GBmod. You think it has a hit now, just wait :)

I had my suspension done for woods, I like it a little soft and Phil down at Aftershocks in Redwood city Calif did it up just right. Here is a pic of my Woods beast with all the mods 2000 yzf426

I settled for a 13/50 setup in gearing the Rekluse clutch and the bike is to fast for me. But I hold on and I look good doing it to :D

Thank you John for the informative links. I will be doing some heavy reading over the next little while. :)

I really like the bike alot, so if I get these minor issues straightened out I'll be in motorcycle heaven(figuratively) :D

The rev limiter works by cutting of the ignition at the prescribed level ( on a 450, it's 11,500. Not sure on a 426, but it's close to that). It turns the ignition back on once the rpm has dropped about 400 or so. If you hold the engine against it it sounds like a regular miss (as opposed to irregular), not a fading or wavering.

One thing that can happen is for either the neutral switch to get stuck closed, or the switch or the lead running to it to get shorted, tricking the CDI into thinking the bike's always in neutral. If this happens, you'll have retarded ignition timing and about a 7000 rpm rev limit. Test for it with an ohm meter by look for the switch to be grounded in neutral and open everywhere else, or by simply unplugging it and seeing if it runs different.

If you hold the engine against it it sounds like a regular miss (as opposed to irregular), not a fading or wavering.

I think you described it better. It is just like a regular miss if you continue to hold the throttle wide open while it's happening, and it happens just a few hundred RPM(give to take) before I would normally change gears. I'm sure it's revving way higher than 7000 before it does it. It doesn't lose power or waver, it just wont rev any higher.

One thing that can happen is for either the neutral switch to get stuck closed, or the switch or the lead running to it to get shorted, tricking the CDI into thinking the bike's always in neutral. If this happens, you'll have retarded ignition timing and about a 7000 rpm rev limit. Test for it with an ohm meter by look for the switch to be grounded in neutral and open everywhere else, or by simply unplugging it and seeing if it runs different.

I'm going to go grab my multimeter now and check this just to be sure. Thank you very much for the advice! :)

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