JB weld on plastic tank

In an earlier post I stated I was about to purchase a WR400 with a seam crack in top of the tank. Will JB weld hold in the hairline crack which is about 3/4" long?

No. You are wasting your time trying to repair this tank with "magic mud". Either plastic weld it or throw it away and buy a new tank. Many people will try to give you advice about shade tree mechanic techniques to repair this tank on a temporary basis. These repairs will eventually fail at the most inopportune moment in time.

X2. Bajafool is absolutely right. I tried every trick in the book and it cost me several really good rides. Never failed I would be on a ride and the fix would fail and I would be leaking fuel. Replace the tank.

A good plastic welder MIGHT be able to effect a lasting repair. Any other method will fail, as said, at the most inopportune moment.

Try bakingsoda and a strong supper glue!!

Take some 60-100 grid sandpaper and sand in and around the crack then fill the crack(if you can)with soda add some drops of glue ontop,this will make a super strong glue hold!!! Try on some other plastic first!!! In south africa they call it Q-BOND!!!!

the only way it'll work is to repair it with the exact same material, not just "some plastic".

Trust me - have a buddy who is a chemical engineer and I checked with him before proceeding with mine.

So, the best thing to do is to shave some strips off the underside of the tank (you don't need much), then plastic weld them using your soldering iron (spotless tip) with a flat tip (preferred but not required).

Gently massage the melting plastic in a circular motion feeding in the strips of shavings as you go - you do not need to penetrate the full thickness. Keep it moving - any color change to green or brown/black means you're going too slow and burning the material - a nono.

Try to build up just a little higher than original, this way you can shave it down to original when done and buff it out if the crack is in a very noticeable spot - then again, it's a dirt bike - scars are normal!!!

Here's a vid of a pro doing it on a structural component - he heated the whole way through for that obvious reason.


I repaired mine with JB Weld and it only lasted 2 1/2 years before it started to leak, if you can afford it buy a new one.

I have a 99 WR400 tank in great condition. PM me if interested.

I am also from South africa , and being from a farm we have done a lot of tank repairs with baking soda , a little bit of soldering acid and super glue- however if you can figure out the plastic weld that works better

I used superglue and baking soda on a cracked number plate the other day, It seems like its pretty solid, we'll see. I was going to do a post about it cause I thought I just made it up. I guess others have tryed it.

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