Triumphrat

stanegoli

On my recent BC adventure I noticed something really weird one day - the tank lobes on my Tiger were rubbing against the forks.

When I went back later to investigate the tank lobes were nowhere near the forks and I thought I must be going nuts. But I could see scrape marks where the tank had appeared to be rubbing......

About the same time I noticed that whenever I opened my gas tank to gas up a LOT of air escaped, and the tank visibly expanded.

It took me a few days to connect the dots and understand that the tank was decompressing to the point where the tank lobes rubbed against the forks, and expanding to normal size when I opened the tank to gas up. It expanded a lot, at least one inch in both directions.

Thinking about this I thought that perhaps all the dirt and mud had blocked the venting tube.

Upon my return to Portland I went to the dealer and he told me there is a service bulletin on the routing of the venting tube and that I needed to take the bike in to have this rerouting done.

I did this today. However the dealer then told me that he has seen this problem a number of times of late. His suspicion is that the chemicals in our gas associated with the Oregon law requiring 10% ethanol was causing the EPA valve to block up and prevent fumes escaping. His solution is to remove the EPA valve completely. The valve apparently serves no purpose other than to satisfy the EPA that gas fumes are minimized.

This is no small issue: my ride partner on our BC ride was riding a BMW Adventure and he noticed the identical tank compression/expansion problem. After we got home and he took a good look at his bike he found that his tank had developed a long crease from the contracting that effectively reduced the tank size about one liter. He now has a big line/dent down the length of his tank.

chisel

There should be a valve that let's air into the tank, but not out. Sometimes this is incorporated into the gas cap. I'm not sure if it's like this on the Tiger. There should be another valve that lets air to the charcoal canister, but not back to the tank. If they're both not pointed in the right direction or get blocked, you'll have expansion/compression problems. Your bike can run rich or lean depending on which condition you end up with.

I believe i read recently there were about 3,000 Sprints (MY2008) that had a similar issue. I'll have to look it up again.

__________________
Those who behave like sheep should not be surprised when they get fleeced.