Tell me about the 2000 YZ426F

YZThumper

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Aug 6, 2001
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#1
I just purchased a 2000 YZ426F and would like to hear the good, the bad and the ugly about this particular model. This bike looks like it rolled off the show-room floor. The previous owner bought over his head and/or riding skill and after only the 2nd ride decided to trade it in. I'm looking for the "What to change" and "What to watch out for" kind of information. I do mostly tight woods riding, but I don't really race . . . I'm more of a weekend warrior, and I try to get more reliability out of a bike as opposed to optimized performance. I have already been told to lower the counter shaft sprocket 1 tooth to a 13 if I'm going to be riding in the tight stuff. I've also heard the clutch on this particular model has issues, but what kind of issues are we talking about, is it the basket or the plates or both ? I've read in another post to use the needle from the 2001 model, any comments on this. I'm a recent 2 Stroke convert (1994 YZ250), and I've only ridden this bike a few times, but man I love the power. What kind of oil do you recommend, and how often to change it on this thumper ? Is it true the factory does a poor job of lubricating the suspension and linkage ? Any insight would be much appreciated.
 

Hick

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Aug 15, 2000
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#2
They added a plate to the clutch for the ’00 model year, but on my bike the (now larger) basket did not clear the cases and rubbed a bit. Its operation also wasn’t what you would call smooth (grabby, chattery). I installed a Hinson and took a little material off the cases where the old basket rubbed. The rivets that hold the backing/gear plate to the basket were rubbing the case where the rear head bolt boss is. The Hinson helped the operation tons, it delivers more oil to the plates than the stocker. But a better option may be to skip the Hinson and install the new clutch parts from the ’01. I have an ’01 and the clutch is worlds better than the ’00.

Here are the different parts:

5JG-16321-00-00 (’01 first friction plate)
5JG-16383-00-00 (“spring”)
5JG-16384-00-00 (seat plate)

I guess you just replace the first plate with the above setup, but I haven’t had my ’01 apart yet to verify this. You also may want to check those numbers before you buy anything...

The other problem I had, and have seen and heard others run into, is a worn straight key that holds the counter balancer drive gear to the crankshaft. This gear mounts to the crank behind the main drive gear. I think the oscillating resistance of the counter balancer is just too much for a soft flywheel key. The ’01 is held on with splines.

Anyway just about everybody with this problem, myself included, swore it was valve train problems making all the noise. Very audible at idle, but don’t panic, they are all noisy. If you cannot move the counter balancer shaft at all independent of any crank movement then you know your key is not rounded off. If you can, even the tiniest bit, you need to check/replace it before bad things happen.

As for the ’01 needle I think that is good advice. On a tip from another board (thanks James Dean jetting kit) I tried an optional ’00 needle (OBEKP) when I first got my ‘00. This is almost identical to the needle that comes in the ’01 (OBEJP), just a half clip pos. leaner, and was a definite improvement. The stock ’00 needle (OBEKR) is too lean on the straight portion (letter R), even for me at 4k ft.

You may also benefit from the installation of a flywheel weight. These bikes stall very easily and can also be a bit of a handful when traction is scarce.

Finally, my ’00 had almost no grease anywhere, this is compounded by the hot oil carried in the frame causing the grease on the steering head bearings to thin out prematurely. Many here will recommend Mobil 15-50 automotive synthetic for your oil changes, I know a lot of people will tell you any synthetic, or any car oil, will toast your clutch, but I probably ran 40 quarts of that through my ’00 and it still has the original plates. I change my oil every five hours or so, but if the bike is as new as you make it sound you should change it more frequently initially.

Hope this helps.
 
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Dec 1, 1999
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#3
The Mobil 1 tip is a good one, ran it in my old '98 YZ400...zero problems...just get the "plain Jane" stuff without the friction modifiers. Change it often in your YZ 426.