11E fuel filter?

[Rob S.]

I know the '82 11E did not come with an external fuel filter, correct?

I recall that from discussions here, and I also recall a general consensus that it was just not necessary. After sitting for 2 1/2 years, Suzi was towed to my mechanic a few months ago, who cleaned and rebuilt the carbs, which had received no maintenance (other than jetting for pods) since I bought her six years ago.

One of the time-consuming chores they did was to repair the choke thumb control, which required hammering and straightening plates and rods. I was told that no jetting or other adjustments/repairs were needed.

I now find I have an external fuel filter, right after the petcock. It's very short and circular, almost looks like it's simply a connector. Perhaps you can see it just to the right of center of this pic, which was taken from the right side of the bike (petcock is on left side of bike).



I have not not spoken to the mechanic about it.

1. Is it in fact a filter?

2. Assuming it is maintained correctly (cleaned or replaced), is there any downside?

I forgot to mention that the petcock was also replaced (or rebuilt). It looks like NOS to me. Lever is hard as a mother to move. Petcock leaked badly when I moved the lever, that's why that was done. My mechanic has all the work he can handle, and doesn't do things that are not needed. (His partner, who did the bulk of the work, used to own an '82 or '83 11E; they're both experts with these old air-cooled beasts.)

I assume they installed the filter because of general age and dirt. Any downsides?

 

[Steve]

That filter <might> be OK. The problem with some filters is that they are designed for automotive use, where the cars have high-pressure pumps for the fuel injection systems. Those filters have to filter out some VERY small crud, which also makes them restrictive. The high-pressure pump tends to overcome that restriction. Our GSes only have gravity for a fuel pump, it's simply not enough to overcome the restriction of some filters. There are filters made for low-pressure systems like our bikes. They are usually in the lawn mower section. Not as restrictive, which means they don't filter the finest of the crud.

You are correct, the external filter was not found on ANY GS, not just your 1100E. There is already a filter on the inlet of the petcock and there is also a filter on the inlet of each carb, so fuel already gets filtered twice, why bother with a third? The quickest way to find out if there is any downside would be one of your infamous blasts down the highway at midnight. If it doesn't starve for fuel, there won't be anything to worry about.

.

 

[Rob S.]

Thanks for the quick response, Steve. I trust that my mechanic would only use the proper type filter. I'm going to (try to) put it out of my mind, which means that yes, it will get "tested" sooner than later, though I rarely ride after dark.

I'll probably put no more than a few thousand miles annually on the bike, but am I correct in guessing that a "failure" of the filter will likely not be a complete breakdown by the side of the road?

 

[Steve]

Since a filter can restrict flow, your best-case situation would be that you simply can't flow enough gas to keep the bowls full and you lose power, slow down (or stop) and wait for the bowls to fill again.

Your worst-case situation would be that the filter will flow just enough to keep the bowls from running dry, but the level will be considerably low. A low fuel level in the bowls will yield a leaner mixture. That leaner mixture will run hotter. Depending on how long you run with that hotter mixture, the pistons might get a little more friendly with the cylinders than the designers intended.

Do your "test". If it feels like it's running out of gas, you will know that you need to remove the filter and/or slow down. If you persist with your "test", expect a dent in your budget for new pistons and other related parts.

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