Fixing the common EX250F (pregen) tank leaking problem: Anyone in ATL wanna try w/me?

[CZroe]

OK, here's the idea:
First, we pitch in to get some of this Caswell Epoxy Gas Tank Sealer and split the cost. It should treat two tanks at a cost of $20 to each of us. It's also great for treating rusted tanks (heck of a lot cheaper than Kreem of POR-15).

After that's ordered, we get some M6 set screws as short as possible and with as low a thread tolerance as possible. It looks like 6mm length is the shortest easily available. Set screws are usually short, head-less bolts that have a hex-cap in the back no thicker than the hole they thread through so that they can go completely inside a threaded hole. They typically secure things to keep them from turning. For example, my aftermarket foot pegs screw on to the adapters and can spin completely upside down. You angle them the way you want (NOT upside down!) by turning to thread them back out of the adapters a bit and then you use a set screw through a tiny hole to keep them in place. The threaded hole goes through the peg perpendicular to the other threads so that the set screw drives right into the side of them and locks it in place.

Next, we get some shorter M6 bolt hardware to accommodate the set screw being in the same threaded hole. The original was 18mm, so subtracting 6mm for the set screw and 2mm to play with makes 10mm length bolts seem appropriate, though we could probably get away with 12mm.

To start, we see if the M6 set screws can screw in until they stop. If they go all the way in and fall in the tank, well, we were also counting how many turns it took for that to happen so we fish it out and go not so far the next time. Next, we back the set screw out a turn and follow the Caswell tank epoxy instructions. Before it solidifies, we turn the set screw again with the liquid epoxy sloshed against it so that it gets the epoxy in the threads and, hopefully, a good seal.

Next, we use the shorter 10mm or 12mm bolts from now on. We may even want to slip a bit of rubber in between the bolt and set screw and melt it to create another seal. A drop of PlastiDip or ABS cement may do the trick just as well if you can ensure that it doesn't contaminate the threads. Not sure how either of those would stand up to gasoline, but if the other seal holds up it won't have to and if it is just a pinhole in the epoxy then it can still help (holds a buffer of air in the thread shaft and may never contact gasoline). Also, the rubber can dampen vibrations conducted from the fairings so that the set screw doesn't back out and break the seal. It's a good reason to stick with 10mm length bolts.

I feel that this WILL work, which excites me because there have been no consistent repeatable fixes that don't involve major work or ruined finishes. Even some of the "successful" ones, like blobbing JB Weld over the bolt hole, losing the fairing mount point, and not giving a damn about the way the otherwise flawless tank looks often fail later on.

[lolibater]

where is it leaking from?

[flynjay]

I just used jb weld on some long M6 bolts in the holes. Put some JB in the hole, apply some to the threads, insert bolt until it stopped. When that setup I cut the head off the bolt so that an acorn nut will fit snug against the fairing. No leaks in the past year.

[CZroe]

Originally Posted by lolibater

where is it leaking from?

Same place as everyone else's: The topmost and frontmost screws on the sides of the tank. I removed a bolt from the tank that came on the bike. It had some kind of thread gasket material on it and it smelled of gasoline.

Originally Posted by flynjay

I just used jb weld on some long M6 bolts in the holes. Put some JB in the hole, apply some to the threads, insert bolt until it stopped. When that setup I cut the head off the bolt so that an acorn nut will fit snug against the fairing. No leaks in the past year.

Glad to hear it. You basically have done the same thing but with a really long "set screw" that protrudes and doesn't need/allow for a smaller bolt. Unfortunately, I've seen way too many JB Weld failures to consider it a viable fix that can be repeated successfully for most afflicted by this. Using a set screw with JB Weld probably isn't a good idea due to thread contamination.