I apologize if this has been discussed, but I searched and didn't find anything. I had put a couple of fuel line filters on my 1992 R100R. I was at a dealership and the head mechanic gave me sh*t for installing the filters. He said they weren't necessary because of the filters at the fuel taps. I see lots of airheads photos here with fuel filters. Is there any consensus about whether they are necessary, or just personal preference? Given the age of the bike, the way I look at it is that it can't hurt having a filter in the fuel line, so I am thinking of reinstalling them. TIA
as far as I can see, with gravity flow to a carb, there can be no way you would impede fuel delivery by adding a filter like this and furthermore...if it did...it would be because something was clogging it, which would be the point of another filter. But I am not an engineer (though I play one on TV). Anyway, point is... to me thats like looking at a van that has 2 spares on the rear doors and saying to the driver...."do you know how statistically unlikely it would be to have 2 flats at once?". I have run mine like this for years and years with no troubles at all so whatever.
If you have the straight Karcomas, it would be worthwhile to check the screens inside the nipple at the bottom. You don't have to drain the tanks or remove the petcocks to check them. I agree with the mechanic, if you have the factory screens in place, the extra filters are not necessary.
From the amount of fine stuff that I see in the filters and in my carb bowls, they are useful. I have run the clear disposable ones, either the small or large ones (they come in right angle too). Auto parts place. I found some trick aluminum ones with a reusable sintered element in a Harly shop and have been using those. The carb bowls are staying clean so I'm happy. I dunno about anybody else but my strait petcocks had screens in the tank and they do get full of flakes of tank lining and other crap. Might have been Everbests. I would investigate. I haven't pulled my angled petcocks to look.
I have worked on SO many bikes with fuel filters and they still had tons of crap in the bowls. Those little clear plastic ones that everyone uses? I have seen bowls full of crap and nothing in those filters SO many times. They do not work. What harm can come from them? From what I see, leaking fuel lines at the filter. I see that all the time. IMO, THAT is what they are good for. The bottom line is that if you really need a filter, what you really need is to clean your tank.
To clean the fuel taps you can run the gas down half way and then lay the tank on it's side to do one petcock, lay on the other side to do the other petcock. I run the gas completely out sometimes so I can hose everything out. I don't think the extra fuel filters hurt and I have some but I have never mounted them just because I don't want the extra hassle. Whether they actually provide any extra filtration or not is debatable as we see on these pages every time the subject comes up. Some very respectable sources say yes and the same references can be cited for the other side. You may use them if you wish. IMHO Charlie
I clean my tanks every decade or two and even then they barely need it. That is not including the one time in 30+ years of street bike riding that I got a tank of bad gas at a local station but that was immediately diagnosed and fixed. But I do put heat in my tank once or twice a year to absorb any moisture.
I use the in line filters. I also clean my tank annually. I've never had leaks around the filters - have no idea what SS is talking about. If that was a case there'd be leaks at the petcock and carb as well. Maybe he's using the wrong fuel ine. I've checked gas flow at the carbs periodically and no problems. I see the in line filters as added insurance.
I'm not using the wrong fuel line since I don't have inline filters on my bikes. I am talking about what I see on customers' bikes. I never put them on any bikes myself since, besides all the leaking I see going on around them, they don't work. At least most all of them I see on bikes. Most all of them could better use the money and attention elsewhere.
I haven't been on this forum for awhile, but I need to say that I go along with the "clean your tank school of thought." The pilot jets especially are susceptible to a few particles stacking up and impeding flow - think alcohol gas eating up layers of years of old crap in the tank. A filter that could catch the small debris would cause the bike to run out of gas in the gravity feed bowl, especially at WFO at low tank levels. With pressurized fuel supply (fuel pump), filters with lower micron ratings could be used to remove the small particles and all would be much better. Just my .02
Anything that gets past my filters will waltz through the jets. The disposables get replaced eery so often (like when they yellow or if I am replacing the fuel lines (about every 2 years), I clean the ones I have now on maintenance day, just back flush the elements with brake cleaner.
um...I wouldn't know. It's a 30 yr old bike this year. Never clean the tank but I should probably pull a petcock and have a look. I do find that with the right angle petcocks (my first) it's easier to set the tank on the ground.
A second fuel filter does no harm if it is working. They are easier to service than the tank fitted filter! Dirt does not just come from the tank but also from the fuel .. dirty fuel can be had in outback Australia and probably other places. ------------ Problems with them? I've had one distort with heat under a PD tank with pot racks and luggage... restricted the fuel flow to around 50mph.
In theory the in tank / Petcock filter should be sufficient, but then there is the real world. In my experience a second in line filter does offer some worthwhile additional protection. As for leaking lines around the filter; I've only ever seen that happen where incorrect size or old/damage fuel lines are used. Here are two photos showing the filters doing their stuff. Plastisonics Filter In tank gauze filter "BMW Airheads Downunder", (The Australia and New Zealand Airhead Community). "B.A.D" http://www.facebook.com/groups/anzairheads/ <hr style="color:#575757; background-color:#575757" size="1">
A couple of us guys had a problem with fuel flow using the small plastic filters. We did the flow test and ended up pitching the filters.
The filters may not be created equally, some get poor mileage (tune issues?) and the filters have to be kept halfway clean. If your tank screens are dirty then the flow is already choked and a filter, even a clean one, might finish it off. Riding BOOH on a 100RS and getting maybe 35MPG I had no problem with dual small strait plastic filters. I have saddle tanks so as those run dry I have super low fuel pressure to the filters. They still work. I have Standard fuel lines, not metric. So a tad undersize. Still works. I only run one petcock (of 4) at a time. Still works. I'd like to say, "oh yeah, do this and you'll have problems" but I have as complex and in some ways marginal a fuel setup as you can get and it works for as fast as the bike will go. I do have my current filters immediately before the carbs. No choice on that. May be a benefit to flow because that point has maximum pressure in the system. I didn't set it up that way with this in mind.
Just installed a new set. The old set were of the triangular sintered type. But they were also very old & discolored. I got the replacements from the bike shop that ordered my new tire. He said he can get tires cheaper than I can at 10% above his cost & it is cheaper than I can find them. Rather give my cash to the local guy. The filters he sells are canister style with paper filters. My tank looks fairly clean, but last year when I went to reserve for the 1st time I also got no fuel. Had to disassemble pet cocks to clear the tubes. Petcock screens were clean and found the reserve tubes clogged.