Melted resevoir???

So I just put a pipe on my 426. The rear brake resevoir was touching so I slanted it slightly to pull it away, but I guess it worked itself back up and now it has melted through.

Has anyone else had this problem before? What's the best solution for preventing this again?

Also, if anyone has a spare resevoir, that would be great. Thanks in advance!

Post some pictures.

will do tomorrow.

I do have a spare reservoir, but the mounting lug is broken off, so it has to be zip-tied to the reservoir guard.

What I did on my '01 250f was to buy an '04 450 master cylinder on eBay for $40 and mount that. Much cleaner. I had to saw off the lug that used to miunt the reservoir, but that's not a problem. You also need to remove the upper bolt and tilt it back to get the cover off to fill it, but that doesn't come up that often, either.

I had the same problem when I was running my WB pipe. I ended up placing heat tile(the silver stuff on the back of a number plate) on the back side of it and it seems to be holding up fine. I did have to replace it though. It was pretty cheap from a dealer less than 20 if I remember right. :excuseme:

Mine is a WB pipe as well. Sorry I couldn't get a pic, I can't find my camera. Gray, do you happen to have a pic of the setup you were talking about? I was already figuring on placing the heat shield on the back like beasley, but I'd like to see what exactly your set-up looks like. Thanks.

I don't have much to input but I do have a rear master cylinder for sale in good condition from an '02 YZ426 if you need...

Would the fancy anodized metal lids help out? Anyone found one for a 426.

I had a similar problem on my yz400 but it didnt' melt right through just the heat from the bike warped and cracked the resevoir, just bought a new one and then stuck heat shield all around it, havn't had a problem since........

Had the same problem on my '01 426, I used a later model master cylinder which has the resevoir built in, I believe it was from a 250F or 450F, but I think they are all the same.



use the 03-05 YZF rear brake master cylinder like stated above. I did that with my YZ426


Thanks, that helps a lot! :ride:

will the later model resevoirs work on the 99 yz400 as well? do they use the same bolts? id get one if it works........plastic just doesn't seem to hold up near the pipe over time.......

So I feel retarded now. :ride:

I got my new resevoir today (haven't been able to find the upgrade yet) and realized my problem. Apparently the bracket that holds the resevoir to the frame was bent slightly back causing it to sit closer to the pipe than normal. Doh!

Anyway. All is well. Thanks TT'ers! :ride:

I simply installed a nylon spacer which created a gap which prevented the melt down on my sons 400. This still allowed for the master cylinder cover to be used. My son was also using the WB exhaust. I think the spacer was about 3/8'' thick.


I rode for quite a while the other day and when I went to use my back brakes, I noticed that they were GONE! It was just like all of the fluid leaked out. When I stopped to investigate, I noticed that there was some fluid coming from around the top and running all the way down from the reservoir to the Master cylinder. I t was hot, so I figured that it either got a rock into and cracked it, or it melted from the heat of the pipe, but I am running a stock exhaust on my 02 426. I never really thought about it getting that hot with the space that there is there. Today when I got on it, it was like nothing ever happened. It was as if the fluid got so hot that it lost viscosity the other day, and after cooling it was normal again. Is it possible for it to get hot enough to do this? Any help with this matter or suggestions will be appreciated.


Yeah I have one of those melted resevoirs. KJR

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