cracked gas tanks

the tank on my 2000 yz426 has cracked after only about 20 hours use. so did the tank on one of my friend's.

i need evidence to support my claim with yamaha, so if all who have stories of similar experiences could post here, it would help tremendously.

thanks in advance.


will pattison

racer, engineer

Where did the crack occur on the tank of you & your buddies bike? If it is on the treads of the tank from the gas cap, I have noticed that more than normal force is needed to "seal" the cap on the 2001 vs. the 2000. This is due to fuel leakage issues that Yamaha said was apparent on the 2000. I have had fuel leakage on my 2001 due to not tightening the gas cap enough, even though it seemed to be tight enough.....If the crack occurs around the rear of the tank where the rubber safety catch is, check the tension of the strap and or the "screw" that it attaches to.

my buddy's tank cracked under the back end, mine is cracked at the upper right radiator shroud mount. neither were the result of crashing or overtightening, the cracks just appeared.


My tank (00) cracked. two hair line cracks on each side in the rear where it goes over the backbone of the frame. You could tell they were stress cracks. The Yamaha shop didnt, even question me, they just replaced it for free plus new graphics(tank only. When I made a comment about the replacement tank not being any different and what happens when it cracks, they told me "bring it back we'll replace it also"

Doug (yammahappy)

WP, I will check mine tonight. I race almost every weekend, have never had any issue with cracks on my "99,2000 or 2001. Yamaha should replace if there is issue. Curious, what part of country do you live in & do you run anything higher than 93 octane?

We are having a similar problem here in Phoenix, and no one has a clue as to why !

The wierd thing is it has happened to a CR, a KX, a CR, and just yesterday a WR250 (2 smoke). The KX was a 95' and the WR a 90'

Only on the newest CR's, both 98's did the dealer help out buy selling it to me at "cost".

Here is what we have concluded :)

Do not keep gas cap tight or tank full, when storing bikes in garage during hot weather months.(any time above 85 deg.)

We believe that our high Phoenix heat causes pressure to build in the tank and cause it to crack.

Any feedback on this would be great.

I also must mention that all my bikes have those " one way vent tubes " in the overflow hose on the gas cap. These valves come stock on the YZF's and WRF's, and do not allow anything out. You will notice this if you here air releasing when you open the cap.

[This message has been edited by Maicoman (edited 04-25-2001).]


How can you build pressure in your tank, they're vented



oops, guess I should finish reading your post before my reply

"SOORY" really wasn't trying to be a smartass



interesting. both cracking incidents i spoke of have happened during relatively cool weather. we both run nothing but 93 octane pump gas.



No harm taken, for being old your not that slow ! You know if I could write better, I wouldn't be a machinist. After reading my post I realized the error also.


Our tank cracking has always been with bikes that used non-race 93 octane fuel also, but all were premixed (2 smokes) and never from abuse or improper tightening of hardware.

Mine cracked at the rear of the tank, while I was at the ROTMX Int'l. race last year.

Yamaha replaced it but warned me to not leave any oxygenated gas (mtbe or ethanol added) in the tank after riding. Seems the problems are mostly in states with that type of gas. I also had my '98 tank crack after 2 yrs. No warranty but I found a place to weld it and it held up fine.

I have cracked two tanks, '99 and '00, and know of two friends also. They all cracked at the rear, same place. I have concluded that it is due to the flexing of the top of the tank where the seat mounts. Over time, it causes cracks at the sharp radius at the rear edge of the tank.

WP, checked mine last night,mine was fine, no cracks. But, while it was off, I inserted a sponge type of cushion under the tank at the rear section, on top of the frame. Hopefully, this may reduce fatique. It does not help that I weigh 200lbs either.

Just a thought and it may be bogus but here is what I am thinking. The YZ set up may apply more pressure to the tank in that location since body position is more forward ann seat angle is different than the WR. Just a thought.

Good luck in dealing with yamaha.

Add another to the list of cracked tanks. Mine went yesterday at Glen Helen, soaked the valve cover and head with gas. I,m just glad it didn't make it's way to that red hot header. I'll let everyone know what Yamaha says when I take it in.

Yamaha says, "No Waranty" only 30 days, go buy a new tank! I'll buy a new one but, it will not be from Yamaha.

Todd, your dealer is full of it, they know there is a problem and are authorized to replace the bad tanks!

Contact Yamaha Customer Service or go to another dealer.

When they replaced mine I asked "what if this one cracks?" They said bring it back and they'll replace it again.

My 99 tank cracked on the bottom rear by the strap. I cleaned it with Simple green and Joy dishsoap and welded it with a heat gun and a piece of a number plate. I removed the hard rubber pad on the rear of the backbone and use foam rubber full length under the tank. so far no leaks. My crack was hairline, my repair was good and I check for leaks often. Don't risk getting gas on the red hot header! I have looked for a non OEM small tank. We are at Yamahas mercy unless you want a 3 gal. tank.


Does anyone have a contact and phone number for Yamaha Customer Service. I trust my dealer, he is a good friend. I think his Yamaha Rep is a D***. Maybe I get some action if I talk to someone else.


i am having the same trouble. apparently, these service reps are sort of like the cia...we know they exist, but they are rarely seen. my dealer's rep acted as judge, jury, and executioner on my tank without ever speaking to me. as a result of some VERY light white spots on my radiator shroud near the mounting point, he concluded that my problem was the result of "impact damage", which is total horseshit. he used the word "impact" in his report to yamaha, and when i called to discuss their denial of the claim, they said they wouldn't touch it unless the rep changes his report or i get a second opinion. the problem is that this rep covers most of texas, oklahoma, and louisiana, so where do i go??

i'm pretty grim, but i'm not done.


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