Curse of the Leaky Petcock

It's been quite awhile since I've had time for a blog. These days I'm doing much less in the way of motorcycling, bike maintenance, and interesting road trips, and a lot more work-related travel and projects in my spare time. That's the way careers go I guess. I've also started commuting via combination of bicycle and public transit several times a week to save some wear on the motorbikes, at least while the weather's nice. Bicycles don't seem to require near as much time, effort, or money to keep running.

This weekend however, I celebrated being off the pager by ignoring work responsibilities and tending to a long-standing issue I've had with the Bandit. One thing about old air-cooled Bandits, sometimes they're leaky. I replaced the head gasket at 16k because it was oozing a little oil. After the Alaska trip the rear caliper bleed screw started oozing a little. The valve cover is currently leaking a little oil at one of the oil journal bolts. And finally, the gas tank has been seeping gas at the petcock seal since before the Alaska trip. This has been an ongoing problem.

Before the trip I replaced the tank/petcock seal o-ring, which stopped the leak for about a week. I noticed a thin sheen of gas under the tank during the trip. When we got home I replaced the gasket again, this time carefully scraping away all the paint, which had started to peel, on the tank sealing surface. This held it again for about a week. Not one to be intimidated, I bought another o-ring and some Hylomar sealant. Again, this held it for about a week.

Not knowing what else to do I bought a fourth o-ring and brought the bike in for its first shop visit in 7 years[1]. The Vallejo Suzuki dealer[2] cleaned out all the sealant and cleaned off the sealing surfaces, then replaced the gasket. The tech said the petcock bolts were loose and suspected that was why it was leaking. $90 well spent, I thought.

So when it started leaking again in another few weeks I left it alone. Like the rest of the Bandit's leaks it was very slow and didn't seem to be dangerous or affect performance. Eventually I explained the saga to my friend Mark who said he'd sealed a leaky gas tank vent with something called Seal-All



So I figured I'd give it a try. I removed the tank, discovering one of the three vent hoses was disconnected. This particular hose has a spring clamp so I'm wondering if Vallejo Suzuki left it that way.

I unbolted the petcock and applied Seal-All to the sealing surfaces, trying to avoid getting any on the o-ring. Note that this should only be done while there's not much gas in the tank. Seal-All looks and smells like model airplane glue. I also put some on the sealing washers that go on the bolts. You can see all the paint I scraped off of the tank sealing surface in a previous attempt:



Finally, bolted the petcock back to the tank:



I'll let the sealer dry overnight, then put the tank back on the bike. I'll post in another week about whether or not attempt #5 was successful.

---

[1] Not counting a trip to Engine Dynamics in 2009 to get a heli-coil in the oil drain. Doh!
[2] I took the Bandit to Berkeley Performance first, but they said they were too busy to work on it.