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Moto Mofo
9/15/2017 8:05am
9/15/2017 8:05am
Edited Date/Time
9/23/2017 8:13am
Found these cracks, one of which has a very slow leak. This is a WR500 tank, which is no longer available and very hard to find. Anyone ever had luck fixing something like this? Being so close to the brass inserts, and the fact that the tank mounts attach at this point may complicate things...
The Shop
Ordered 1/4" HDPE rod from McMaster-Carr and welded up a few tanks. Here's the KX80 tank I had to re-work to get the XR100 motor to fit.
Most tanks are an HDPE mix of some secret proportion, but straight HDPE will bond very well. I would "V" out that tank and cracks and weld in that nut so it doesn't spin.
Good luck!
I can see how the v notch is important, if you simply run a soldering iron over the crack, you are only making a 1mm or less "patch". The vibration will open that thin layer in no time.
IMO Yamaha tanks are the most notorious for cracking, going back many years!
I usually use the tip of that welding nozzle to create the "V" by "plowing" it into whatever I'm welding. Then I'm pushing the HDPE rod through the nozzle and filling the gap. While in process, the white HDPE rod will turn clear and you should be able to tell when the tank material is hot enough to bond. Takes practice, but it's a cool process. Try it on a junk panel or fender first!
I got a little more gas smell during welding, but a dry tank can't be of danger, except for catching the plastic on fire itself. If that happens, you're doing it wrong...way wrong!
Look up my YZ125 race build also. I repaired a .22 slug hole in that tank the same way. No leaks after many races and abuse..
Post a reply to: Anyone ever had any success repairing cracks in plastic gas tanks?