The Gas Filter vs No Gas Filter Debate - Humorous Finding

[twistedwankel]

For those of you standing on both sides of the inline gas filter debate or straddling the fence on that issue I have a new finding.

My bike came with an inline filter and it was on there for most of it's 27 years and yellowed with age. So I assumed it must be a harmless idea and firmly supported it's use. Simply because I never had a problem.

When I had to take my tank off completely to evaluate a performance issue I finally noticed that the fuel filter was installed on the vacuum line and not the gas line.

I suppose this would explain why it lasted so long? hahahaha

Anyhow. I did put a new one on the "gas line" recently as am concerned with the 10% ethanol mandate which will most likely strip any rust from my old tank and my new use of Sea Foam to clean the system including the in tank screen.

So far so good. No performance issues are noted and I carry a spare one with me should there ever be an issue.

BUT I have to support those who always said to not use them as obviously I never have either The in tank screens must be pretty good after all as mine are original and both the normal flow and reserve screens still function perfectly.

I hope you got a chuckle out of this....I did when I found it.

Genius is finite and rare....Stupidity knows no bounds.

 

[emjay]

That was great! I wonder if it affected the vacuum pressure at all.

Generally I've found that the in-line filters limit the flow of fuel. Often people install to try to fix carb issues. I'ds say if you really think you need a better filter then you should probably replace the petcock.

 

[spyug]

Interesting finding. I guess you need a filter to keep the vacuum clean:-D

I'm of mixed emotions on this subject. I have always thought that with older bikes and their potential for rust in the tanks several filters can't be bad. I've put them on the 3 previous Yammies that I've owned and never really felt they caused any problems.

With the GS, it came with one small filter which I changed first thing as the bike had been sitting 7+ years and I wasn't sure if it was plugged or otherwise defective. With it installed I found the bike wouldn't run as well as with it off. Thinking that it might have been too small I changed it for something larger but the bike still didn't idle as nicely as without one.

For now, I am running filterless but I'll experiment some more as I still think filters are like money in the bank....you can't have too many.

Anyone else have issues with them?

Cheers all,
Spyug.

 

[oldryder]

Overall I believe they're a good idea on old bikes if properly sized. I once spent a whole afternoon of a cross country trip in a parking lot in the BLAZING arizona sun cleaning rust from carbs(no filter) so I'm kinda biased.

In my experience they do not cause problems unless they're plugged and if they are thats a lot better than letting that same debris into your carbs.

 

[Guest]

From experience, this is a good idea on a bike that has been sitting for some time especially, in the first few thousand miles. Petcocks only have a filter screen, which will not remove the really small (micron range) bits of iron.

On one bike I brought back to life, I clogged 2(!!!) inline fuel filters within the first 1500 miles. I would much rather have that be in the filter in the trash than the carbs.

However, it can definitly reduce the flow available to the carbs, and I have on occasion, after running flat out for a minute or more, had one bike sputter, almost run out of gas, then just barely catch and come back as I come back down to about 65 on the highway.

 

[tkent02]

You can test them....
Gas in the tank, hose into a container of known size at about the same level as the float bowls. Suck on the vacuum line to open the petcock. Time how long it takes to fill the container. Do it once with and once without the filter installed. Lets say it fills a quart container in seventy five seconds, that's a gallon in five minutes, even at wide open in top gear your engine can't possibly burn that much, the filter flows enough.

Filters for little dirt bikes may not flow enough. Filters for cars will not flow enough without a fuel pump to assist. Old crappy filters won't flow enough either but then neither would your carburetors if they had the same amount of crap in them.

That said, I don't usually run filters if the tank is clean inside.
The petcock screen is usually good enough.

 

[t3rmin]

You can test them....
Gas in the tank, hose into a container of known size at about the same level as the float bowls. Suck on the vacuum line to open the petcock. Time how long it takes to fill the container. Do it once with and once without the filter installed. Lets say it fills a quart container in seventy five seconds, that's a gallon in five minutes, even at wide open in top gear your engine can't possibly burn that much, the filter flows enough.

Thank you. I've been saying this all along. If you have any doubts, just observe the flow. Then think about how long you can drive around on one tank, and how little the required flow must be if you can drive around that long.

I've never had a problem with a generic in-line filter from the auto parts store. I've used the metal ones, the plastic ones, the big ones, the small ones (prefer big, but sometimes space is tight). Observed flow is always quite healthy.

It's cheap insurance. These bikes are old and most of them have at least a little rust in the tank. I consider the anti-filter sentiment predominantly superstition. Sorry. ;-)

 

[TheCafeKid]

Thank you. I've been saying this all along. If you have any doubts, just observe the flow. Then think about how long you can drive around on one tank, and how little the flow must be if you can drive around that long.

I've never had a problem with a generic in-line filter from the auto parts store. I've used the metal ones, the plastic ones, the big ones, the small ones (prefer big, but sometimes space is tight). Observed flow is always quite healthy.

It's cheap insurance. These bikes are old and most of them have at least a little rust in the tank. I consider the anti-filter sentiment predominantly superstition. Sorry. ;-)

+1. Never had a problem. Only way i could really even see a problem is if the filter wasnt kept parallel (man that doenst look spelled right) with the fuel line. Even then, i dont know that it would cause an issue.

 

[t3rmin]

I have TWO filters on my XS11 (one for each petcock/carb bank). Take THAT, anti-filter activists! ;-)

 

[tkent02]

Then think about how long you can drive around on one tank, and how little the required flow must be if you can drive around that long.

Actually the required rate is quite high at sustained full throttle, such as up a long grade at highway speeds, cruising the Autobahn, or some forms of racing. The rate I quoted (one gallon in five minutes) would result in about 12.5 mpg, running at about 150mph, just my guess at what a large GS would do at high power.

There's probably an actual flow number for each model engine somewhere, I don't have it.

 

[Nessism]

The filters with the brass stone on the inside create minimum restriction and help supplement the stock screen filters. I’ve checked the flow on my bike and can’t see how they can cause a problem. One caution is to make sure the fuel line does not loop upward when adding a filter; the loop will create a restriction which may cause erratic running when the fuel level gets low in the tank.

 

[t3rmin]

Actually the required rate is quite high at sustained full throttle, such as up a long grade at highway speeds, cruising the Autobahn, or some forms of racing. The rate I quoted (one gallon in five minutes) would result in about 12.5 mpg, running at about 150mph, just my guess at what a large GS would do at high power.

There's probably an actual flow number for each model engine somewhere, I don't have it.

Well it's true there'll be higher peak flow requirements. But the way every filter I've used flows, you're well within any kind of reasonable requirements, peak or otherwise.

I've seen a lot of people make multiple changes at once when chasing down some gremlin, then when the problem is solved, proclaim it was the fuel filter. I've never personally witnessed or read any account where I was convinced removing a fuel filter solved the problem. And they sure as heck can help prevent carb problems down the road.