I don't know what happened, the bike was pulling hard on 5th speed... suddenly, heard some noise in the engine, it stopped and the rear wheel stoped to.

I thought: "that's it, the engine is blown !!" but, I could check that kicking and with the clutch pulled back the piston was working...

... Opened the cranckcase and that it was: one gear was almost completly broken. There was only 2 gears left (on both shafts) in condition. All the other had many theef broken and bent.

Can you believe this ?

And more: the bits of gear, went into the crankshaft damaging it (fortunally only scratches) and they scratched the down side of the piston and cylinder.

I'm very disapointed and I fear the reparation bill...

However, I heard some talks that the WR400's gear box would fit in the YZ426F engine and, having all this, I'm considering to purchase the WR400 gear wheels.

Have you or some friend of yours ever done this ? Is it possible ?

Greetings from Europe.


sm- sorry to hear about your run of bad luck. I read a post on news.motorcyles.dirt about the very thing you mentioned, putting the WR gearing in a YZF. I had an email from another owner who had done this to their bike and I looked but I can't seem to find it now. You might go to that newsgroup and post this same question and I'm sure someone will have details, that's where i got this info...


You're not the first to post about broken gears on the 426. I'm getting a little concerned........ :)

...So do I...

Can you tell us where did you read about guys getting their 426 gears broken ?

If you change the post time frame to the last 100 days, you'll see that two others have posted about broken gears on the 426 (third gear and fourth gear).

No trouble on my 426.

... maaannn ... :D:):D:D

I had no idea of this...

This seems to be a very big problem for Yamaha... and I thought I was a very rare case...

I'm in trouble, my YZ426Fs warranty is gone and i'm fearing that I will have to wait a lot (since my country seems to be always the last one...) and the cost is going to be high.

The very same thing: 3rd and 4th gear wheels and pinions completely ripped !!!!

I really thought I was an exception in the world and I regret not reading your posts long before :D:D:D:D

Now, I shall wait and see what Yamaha Portugal is going to do about this.

But I promise, if things are going to be hard, I will create a post in this forum saying that Yamaha sucks ! :D:D:D:D

I also own a Honda CBR 1000F since 1997 and, despite being a very different bike, it has never had any kind of problems !!!

That's it guys, sorry for being this "melodramatic" and wish me luck !

P.S.: I'll be back ! :D:D:D:D

Demand that Yamaha fixes this problem. My bike was out of warranty by 2 1/2 months and they still paid for the repairs (about $1400 US) Mine now has 5 new gears, Hinson basket and Pressure plate (I bought those) and is for sale. Yamaha knows that there was a problem with early built and sold 426's (I was told this by the dealer) and should be able to tell if in fact your bike was one of the ones that had this problem (by serial #)It took many phone calls and trips to the dealer to get this done but in the end they did the repairs.

Good Luck and stay on the phone with Yamaha.

The 426 is an awesome machine, however I'm afraid to ride it hard so it's a gonner for me. I have a KTM SX520 ordered. See what happens with that.

Thumpers Rule!

I've got a problem!

As the warranty was gone and I had no idea of this being a manufactory defect, I opened the engine myself...

Because of this I have no conditions to demand anything to Yamaha.

But one thing is for sure: I'm very disappointed with Yamaha's YZ426F.

It's one of that things in life: At first is the best thing in the world, a dream, but in the end, it turns into a nightmare.

I'm feeling very sad because I regret not knowing that this was happening to more people and I trusted Yamaha too much...

I shouldn't have opened the engine myself but, anyway, I think Yamaha should help us (Yamaha trusters) on making some discounts in the parts ordered.

That's all folks!

After all this, my hearth is moving into Honda.


Portugal - Europe

You need to get a hold of Yamaha and get to there Consumer Affairs department. The things you need to say if you can,

1)How many new Yamaha's you own and/or have bought.

2)How many Yamaha's you are going to buy, "I was going to trade this bike in on 2001, but now, I'm not sure.

3)How much you spend in "YAMAHA" parts and accessories. "I've only used Yamalube and Yamaha filters, I've had to replace my fenders and I only buy Yamaha parts, they are the best."

4)Make sure you tell them how much you love the bike and how well you have taken care of it.

5)Don't demand, state your case, over state your desire for repair, "I want a complete replacement engine." but, back down and take whatever they give you. these tips will take you a long way when dealing with any manufacturer

As far as getting a hold of them. Your dealer should be able to provide you with a contact number or go to their website at:

Good luck.


Derwood, traped in IL


sm- I recently bought a used fixer-upper '95 YZ250 from a friend. I promptly took it apart down to the frame, and completely re-built the engine (my first re-build) I knew from the start that if I sold it right after I finished it that it would only be worth about what I gave for it before I started the work. That's how I ended up with this YZ426 also, I fell in love with this bike while going to the Yam shop every week or so for parts on the 250. The 250 is finished now and it is for sale, asking about 500 less than I have invested but the knowledge I gained was worth much more to me than this. Go ahead and fix your bike and ride it like it's new, you only live once...


SM; I realize your frustation as I have been riding bikes for over 20 years and have had many weird things happen. I hope this will shed some light and ease your fear. I had a Honda support ride in 1983. Free bike, parts, etc. Blew up the tranny after six weeks. Found out that it was a common problem with the 83. Not even the factory Honda rep could do anything for me, since many had been ordered and I think the engineering dept went back to the old drawing board before they made more. A honda rider, and familiar with the tranny,(there was a small pattern here)I deciced to order the entire 82 gearbox and it worked but I missed several weeks of races and precious points. HONDA COULDN'T EVEN TELL ME THIS WOULD WORK!!! So in regards to "going to Honda" I believe that Honda's are probably the most dependable dirt bikes going but be careful what you wish for. To ease your fear a little. On the other hand I also was the second owner of a 78 yz 125 which apparently had a problem with the crankshaft insert coming loose of the case. I was the second owner and in 1979 with the help of the most helpful partsperson I have ever known, Yamaha replaced both crank case halfs, half of the crank, gaskets, seals, etc. Did I mention that I was the second owner? What kind of deal will you make me on that 426? Have some patience, difficult when you lose riding time on a YZF, and follow the instructions of the previous response, that person is a true diplomat, and you might be suprised what comes of this. Good luck!

Not a diplomat, just in the know on how to get something from the Manufactures. They are a tough nut to crack sometimes. You gotta speak to what they know and want, "Incremental Sales!"



trapped in IL.

I've escaped! I'm heading back to Cali and beautiful Jawbone and Glamis......




If You try to ride Your CBR 1000 the same way that You do Your YZ thumper it will shatter gearboxes to.

I competed in the Nordic Fireblade Cup for a couple of years ago and shattered my 1993 Blades gearbox three times.

I also bent 2 piston rods twice.

Please keep in mind: this is a race bike and it is surely not the first with some "smaller" problems.



I feel your pain ma man. Aside from the people that are trying to calm your nerves with explanations, I too had my gearbox fail. Just know that you won't get anywhere with Consumer Affairs, as I didn't after 10 phone calls and many plea's. If you broke the motor open, Yamaha will say to take a hike. Read my post's on "Broken 426 and 250 Gearbox's." I raced Honda's for 8 years up until 1994, never one tranny problem, never a clutch failure, and only one top end failure. Ya know what....Honda replaced everything, even though the bike was way out of it's warranty. I brought the parts to my local shop and they called Honda for me. When I say that I will switch to Honda, I will do it out of loyalty to those manufactures that have helped me out before. I can't remotely say that about Yamaha. Here's something to think about:

Why would a gear be back ordered for 2 months? Mine was. It's reassuring that I bought a 6K dollar motorcycle and missed two months of riding, along with Yamaha telling me I'm SOL. Yamaha recognized they had a problem and they either took all their gears out of stock to retool for better ones, or they ran out of their stock of 4th gears because many people were failing them along with 250's doing the same since they share the same part number. So, Derwood and friends can try and calm your nerves, but does it make you want to go down to your local Yamaha dealer and buy that new 426? Not me. I'll wait for Honda's RC450.

Originally posted by Numpsy:


If You try to ride Your CBR 1000 the same way that You do Your YZ thumper it will shatter gearboxes to.

I competed in the Nordic Fireblade Cup for a couple of years ago and shattered my 1993 Blades gearbox three times.

I also bent 2 piston rods twice.

Please keep in mind: this is a race bike and it is surely not the first with some "smaller" problems.


I would agree with you if I haven't had a Cagiva T4-500E since 1989.

This baby was treated equally (or even worse) than my new 426 and the only (major) problem it has had was a cracked cilynder head.

She has had this problem since I discouvered it and I haven't solved it because a new head was a little expensive.


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now