Fuel Filters????

I thought that I had problems with the mixture leaning out at high revs. Someone suggested that I had a fuel flow problem instead. They were right. Changing the apparently slightly clogged inline aftermarket fuel filter improved the performance dramatically, but not completely.

Of course there are/could be many other factors affecting the engine's condition, but ... Is fuel flow from the tank to the carbs commonly one of them?

It seems that the stock system has no inline filter, is this true? If it is, then wouldn't an inline filter be an impedance to the flow?

There is not much room under the tank for a larger filter, that would have a larger filter surface area and offer less impedance. I have even considered trying to go with multiple filters piped parallel.

Any thoughts panel of experts?

Multiple filters inline would reduce flow even more. I came across a glass tube inline filter that is much bigger than the one I got from z1enterprises.com, and though I could *barely* get it to fit it it allows for better flow.

I'll post a picture of what I put in place. It's big, ugly, and effective.

Hi, I'm back. . .here it is, what do you think?



:lol:

Post edited by: KaZooCruiser, at: 2007/02/22 18:24

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Fuel tank should be reasonably clean inside and free from rust particles, grit, etc., otherwise the petcock filters are usually first to clog. But let's say good fresh clean fuel is flowing from inside the tank through the petcock into the fuel line where it meets the in-line fuel filter. Without having timed such an experiment, I would bet on being able to empty a full tank within a few minutes of free flow through a clean in-line filter. So a single small inexpensive filter flows plenty of gasoline for street use. Yes the bike came new with only the petcock filters (on the tubes up into the tank interior and on sediment bowl), but our older bikes (especially inside the carbs) usually benefit from increased filtration afforded by addition of an in-line filter.

Post edited by: Patton, at: 2007/02/21 14:02

Napa sells those same fuel filters, but for almost twice the price...I'd stick with Z1. I just bought one from Napa and will try and install it this weekend. I'll post the results of my success or failure.

I use 2 of the filters shown above on my KZ with an 1135cc kit and 33mm. carbs, and have no flow problems.I put 1 on each inlet to the carbs.If you are findind they fill with crap you may need to have your tank sealed inside.Don't forget to clean the screen in the petcock valve.

Qdude wrote:

I thought that I had problems with the mixture leaning out at high revs. Someone suggested that I had a fuel flow problem instead. They were right. Changing the apparently slightly clogged inline aftermarket fuel filter improved the performance dramatically, but not completely.

Of course there are/could be many other factors affecting the engine's condition, but ... Is fuel flow from the tank to the carbs commonly one of them?

It seems that the stock system has no inline filter, is this true? If it is, then wouldn't an inline filter be an impedance to the flow?

There is not much room under the tank for a larger filter, that would have a larger filter surface area and offer less impedance. I have even considered trying to go with multiple filters piped parallel.

Any thoughts panel of experts?

I just don't think it would be out of the question to install an after market (like, duhhh) electric fuel pump to take gravity fed fuel and boost the pressure, thereby increasing the flow rate into bowls. Obviously, this would be most beneficial only under __HEAVY__ acceleration. I want to piddle around with that concept. Will let you know if I come up with anything.
As long as the fuel cut-off needle valve is doing it's job correctly, the fuel pump would be "invisible" until extra fuel is needed, like, right now.

Post edited by: JimatMilkyWay, at: 2007/02/21 20:36

I use the NAPA p/n 3011 filters on both bikes, lawn tractor, and brother in law's VW beetle with no problems whatsoever. They tuck in nicely under the tanks and only take up 2" of fuel line length.


Post edited by: oldcoldankles, at: 2007/03/10 16:31

Qdude wrote:

I thought that I had problems with the mixture leaning out at high revs. Someone suggested that I had a fuel flow problem instead. They were right.

You have an old bike. . .

I remembered something from a bike I had years ago. Maybe you have gotten the problem fixed by now.
Sometimes the vent inside of the gas cap gets blocked from contamination. If that happens, fuel gets vacuum locked inside of the tank, preventing it from flowing correctly.

The bike was a Suzuki TS-185 in otherwise pristine condition. It had been at the shop for a stalling condition. It would run for about 10 minutes, and then shut off. The mechanic thought it was the coil, and then when that didn't fix the problem, he thought it was the CDI box or magneto trigger, which the owner didn't want to buy, so there the bike sat, with a repair bill still outstanding and an unresolved repair issue.

Of course, I got the bike for cheap from the owner, who didn't want to spend anything on it, and for the cost of the outstanding mechanic's lien. Somewhere along the line the lacquer on the magneto trigger was damaged before I got it, so I had to fix that and because that wasn't the problem, the bike would still shut off.

While dealing with this issue, I was cruising down the road at about 35 mph when it shut off, like someone had turned off the key. I popped the gas cap and the bike roared back to activity. Cheap fix.

When he found out I got the bike fixed, the shop owner called me a dog, and accused me of being a thief, but I just smiled, because I figured he was already wrong about other things, what was one more?

I used a piece of broken guitar string to poke out the rust in the vent hole. Being an occasional musician provides a great source of different gauge wires. It can provide hours of entertainment.

Fuel dilevery with with fuel filters gets talked about all the time.
The fuel filter only has to be big enough to flow as fast as fast as the flow from the needle and seat to keep up, or is that wrong? :S

I have one on mine made for snowmobiles that is made with a 90 degree turn built in...but it seems to loose a little OOMPH! using the filter instead of a straight fuel line. Maybe it's just me. :whistle:

Hello, had problems with inline filters(the ones with brass filters inside around 1/2inch brass filter element diameter) when the tank was nearly empty or on reserve.My motorcycle showed signs it was starving of fuel, sputtering, sometimes backfiring thru carbs. I installed it because my tank was rusty, but I noticed that even with the inline filter the finer rust particles still ended up in the float bowl. I'm still looking for an inline filter that would filter the finer particles but the paper element filters that I have so far tried( I tried the small sizes), is just not flowing sufficiently to feed the bike.

Post edited by: jeffreygp, at: 2007/03/10 16:17