IMS tank leaks at petcock

I picked up a used IMS YZ seat and tank set-up for my WR. After installing all the hardware and gas line and pouring in approximately 1 gallon of gas I noticed a leak at the petcock where the rubber seal mates with the bottom of the tank. I loosened up the 2 mounting screws to make sure they were tightened evenly...all the while gas was draining at an alarming rate down my arm and on to the garage floor. This did not seem to help regardless of how tight I tightened the screws. I would say they are past the 5 ft/lbs torque per the manual. I checked the stock tank and my old Clarke tank from my RM and they both have an indentation where the petcock sets in while the IMS does not have this feature. I wonder if this feature helps control flatness in the sealing area. When I tighten the screws the sealing surface does not appear to be flat(it's bowed up in the middle where it leaks - approxmately .020").

I checked the rubber gasket and everything appeared to be fine.

The petcock is rotated 180 would this adversely affect anything?

Anybody experienced a similar problem? Are there any sealers I might use? Any input would be greatly appreciated.


2000 Yamaha WR400F

1988 Honda NT650 Hawk

1977 Suzuki RM250B

1974 Honda XR75K1

My buddy bought an IMS tank that did the same thing. He called them and they offered to replace it but, said that if he would just file the surface flat it should be fine. Just give them a call he said they were very helpful.


Nathan Apelbaum

99 WR400F

97 YZF1000

99 400EX

95 RA1100

Mike I agree with Nathan it sounds like you have a little bit of a convex surface around the rubber seal area. File it down so that it is a slight concave surface ad I am sure it will help. Wish I could suggest a good sealant for gas but I have no experiance with it.

Thanks Nathan that sounds like some good advice concerning filing that surface. I'll look into that tomorrow. Hopefully I can get it flat enough to seal.

When I put my clarke take on I noticed it leaking a small amount of gas around the petcock. After taking the petcock back off and looking at it very closely, I found a very small, piece of dirt that was allowing enought gas to leak through. It was hard to see, but it dosent take much.

Just a suggestion.


Darin from Missouri WR400F Pro-Tapers, Applied TC, Clarke 3.3, YZ seat, Scotts Shark Fin, FMF PC IV S.A., One Industries Hannah Retro Kit, WER Steering Dampner,Pacemaker Computer, Andrews Powder Coating-painted gloss black

I bought my tank used as well and it well :) Turned out I didn't have the gasket! Anyway I called IMS and they shipped me one out, no charge.

Call'm, I bet they try to do anything they can to help.


Chris in the Mojave

'98 YZ400F

Chris you said that they sent you a gasket. Do they make a secondary gasket that fits between the petcock and their tank? Or were you referring to a replacement of the stock one? Thanks-

loctite 515 on the gasket.

There is a BIG BLACK FLAT RUBBER GASKET that comes in the IMS kit with the tank. And as I remember there is a little O-ring like gasket on the petcock.

You NEED both :)

Mine leaked just as you discribed BEFORE I got the the gasket from IMS. After the gasket...dry.


Chris in the Mojave

'98 YZ400F

Thanks guys for all the help! I went and filed the high spots which happened to be the metal threaded inserts that are molded into the tank for the petcock screws. After 2 tries I got it to seal...then I decided because of the proximity to the hot head pipe that I would use lock-tite sealer as well. Now after reading the latest post I plan on giving IMS a call tomorrow and inquiring about their gasket. It makes you wonder if this is a fix IMS came up with after getting alot of complaints from their customers or was it somthing that has always came with their tanks?

for what it's worth, I put the ims tank on with the washer/gaskets that came with leaks first time.....months later, still dry


99 WR400-FMF 909 topclamp,FMF MegaMax II full pipe, IMS seat/tank,Renthal bars,Acerbis rally pro guards

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