Overheating problem solved! (I think)

Some time ago I posted a note about my 426 blowing coolant from the overflow. Many of you gave me some great suggestions. I replaced the radiator cap with one from an auto parts store rated at 13psi. Which didn't help. The original cap on these bikes is metric 1.1nm/cm2. After some searching for conversions on the net, I found that 1.1 is about 16psi. So I've purchased a replacement cap and will try it this weekend. I'll let you all know if it solves the problem.


I had that problem on my 98. I bought a cap from the dealer for $40. It was expensive but it worked.

Thanks for adding the price to your reply. I couldn't believe it when I paid $30.00 at Honda! I about fell over. I've said it before here. One day I'm gonna up and sell this YZ and buy a late 90's cr500. Poor handling, heavy, overpowered, dated, runs forever. Sounds like my next bike. Maybe if I keep putting Honda parts on my YZ, it'll act like a CR. Sorry for the vent. My 426 was the first new bike I've bought since my 1980 xr80. In many ways it lives up to the hype and then some, but I've never felt like I could completely trust it to get me home from a long ride. I'ts never left me stranded, but I've worried plenty. On the other hand, this is a great board! I love reading about the bike I love/hate. Thump on!


I hate to make you guys sick but you can go to the local Auto Parts Store(my example is O'Reilly and Auto Zone) and pick one up for 5 dollars. The Yamaha OEM Replacement is 1.1(15.6lbs) and the ones at the Parts Stores are 16lbs. I went that route as mine was getting weak and allowing the bike to overheat in tight woods. Not had a problem since.

My 98 over heated on a concrete starting pad about a year ago and did so just as the 30 sec. board went sideways (can you say %#*#@!) I was told by friends to up the pressure rating on the cap. That didn't seem like such a good idea to me. Beacuse your increasing the pressure of the entire system. What I did instead was started using a product called "Engine Ice". Its a toxic free, anti-freeze type product. I live in So/cal and race through the hot summer months, and I have never had another overheating problem.

Well it wasn't the cap! I guess I do have a head gasket problem. A local bike mechanic told me that cometic gaskets are junk. I guess I'll have to put a new yamaha gasket on it. Bummer.

Thanks again for all the advice and ideas.


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