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The other night I got a good laugh when I was looking through this blog’s statistics.  See, I know how you got here, who you are, where you came from…but I digress.  Anyway, this little site was found via a google.com search with the entry “hate my yz426″.  Been there, done that.

I bought my 2000 YZ426f back in late 2001, only a couple of months after I moved to Arizona.  It was from a co-worker and the bike was geared for speed.  I am a trail guy and as time as passed, I have migrated to slower more technical trails versus the high-speed stuff.  Heh - we call them ‘goat trails’ out here.

Shortly after taking ownership of the bike, I hated it…so much that it was almost on cycletrader.com a couple of times.  Hated it, hated it, hated it for the following reasons:

• Wayyy to much fuel being delivered to the engine.  This caused the bike to stall the instant that he RPMs dropped to a lower range or if the throttle was chopped.  It even had difficulties using the hot start.
• The bike was an absolute bitch to start, especially if it had sat for a while.  I had several times where I had to abort riding because it simply wouldn’t start after about thirty minutes of trying.
• The clutch action was terrible and inprecise.
• Low end was minimal, and it could not lug at all.

A couple of the above items, I simply learned to live with, especially the last two.  The first two made me hate the bike rather quickly, and the fueling problem contributed to a low speed crash in which I stalled the bike where and broke my ankle and required surgery.   Ultimately, the crash was my fault, but I stalled the bike at the most inopportune time while climbing a mountain.

That crash bought me a three month vacation from riding.  My first thought was the easy way out - sell it.  Fortunately, I started reading up on the bike and stumbled across the forum Thumper Talk.  It has been the greatest source of information at how to make the YZ426 work.  It’s full of guys who race and need them to be right.  Anyway, all of the above problems were ably addressed by making mods that had well-detailed instructions - well enough that I even got it right.

Here are the mods I did to the bike.  Just login to TT and do the searching part yourself as there are many threads on each topic.

1. The easiest was the “blue wire mod”.  The claim at the time was that unhooking the light blue wire from the /cdi box gave full spark to the bike while in neutral (read: while starting the bike).  The discussion stated that there is a built-in safety mechanism to manage the spark if in neutral so that you could not over-rev the engine and cause damage.  There seems to be some skepticism as to if it really makes a difference.  I did it and have had no mechanical failures or problems.
2. The second easiest mod was the clutch upgrade.  This is only necessary for the 2000 models.  Apparently they got rid of the ball on the end of the pushrod which killed the feel of the clutch.  The 2001 and later models had the countermeasure parts.  You simply buy the 2001 pushrod, ball, and a clutch plate or two and all becomes well.
3. Next is the PowerNOW valve.  Actually, I went with a copy called the JamesNOW mod, and for $10 got a fitted plate from…well…a guy named James.  Its a flat piece of thin sheet metal that fits in your carb velocity stack to divide the intake area in half.  At small throttle openings, this mod will divide the area for the air to travel into the carb in half, therefore speeding it up.  Search for JamesNOW and you’ll get the full (and better) explanation.
4. Finally, there is the accelerator pump set screw mod.  I think this made the biggest contribution to the bike becoming fun to ride.  You drill and tap a hole in the carb body and insert a small, but long screw to control the accelerator pump fuel amount.  Some of the 426 veterans, through trial and error, figured out that the optimum ’squirt duration’ is 0.3 seconds.  My OE setup had a squirt duration of about 1.8 seconds.  You can figure that six times the amount of fuel would make starting the bike, riding the bike at lower rpm, and throttle management very difficult.  I got it to around 0.3 seconds and it was a whole new bike.

These mods have made the bike a keeper.  I have had it now for five years now and still enjoy riding it.  It sits for months at times :(, but always starts on the first kick.  I can lug along with proper fueling - granted I did change the gearing - and I can’t remember the last time I stalled the bike.  Heh - the last time I had an off, the bike stayed running, I picked it up, and off I went again.  I also think that dialing in the fueling gave the bike ‘hit’, like a two stroke, without any bogging.  Finally, the clutch is much better and more useable.  The grabbiness is gone and feathering the throttle to aid in technical trails is much easier.

Yeah, I used to hate my YZ426f just like the guy on google.  That said, I think this particular bike has the current record for length of time of ownership.  That says a lot given my motorcycle stable’s history.  Before you sell the bike out of anger and/or frustration, give the mods above a try.  It transformed my dirt bike and will likely transform yours too.

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