Glass inline fuel filter?

Discussion in 'General Questions' started by Fletch, Feb 11, 2011.

  1. Fletch

    Fletch Member

    What do you guys think about glass fuel filters like this one? I was given one, and it looks like the paper probably filters better, but this one might have a higher flow? It looks cooler for sure.

    Attached Files:

  2. RedBaronX

    RedBaronX Member

    I have a glass filter, but the filtering part is a mesh of some sort, not paper. Otherwise looks gosh darned similar. I like it, but it's also the only one I've used, so I have no stories for comparison
  3. yimmie

    yimmie Member

    i have a glass 1 like that but have not used it yet
  4. professor

    professor Active Member

    Don't try to run a paper element filter in a gravity feed system because it will stop flowing after time goes by.
    The filters with a fine screen (looks like the one in the pic has that) are the ones to use.
  5. Htown

    Htown Member

    used to run these on my Buick Rivs, work great.
  6. Fletch

    Fletch Member

    Thanks for the replies. I threw it on the bike yesterday and rode for 40 miles. It ran great. I think it might improve the flow to the carb. Mine is mesh like the one pictured- no paper. I was talking about the stock paper filters.

    I made it up this monster hill that I usually have trouble on with ease. I don't know how much to credit the filter because I put an o ring in the carb as well, and pushed in the float toggle where some fuel was leaking out.
    Last edited: Feb 12, 2011
  7. Dave C

    Dave C Member

    That's the only problem with doing a bunch of mods, which one did how much?:whistling: It's like I have no idea how my bike runs stock. From the begining I was upgrading, sick bike parts is in my favorites list. Without buying a shift kit I've bought almost all the upgrades from them they have. Except the new billet covers:ack2: Nice, very nice, just can't justify the cost. They're like racing stripes on a car; look good, don't go no faster or make more power.

    Now, if they make a new cover for the clutch arm I'm there. When I had that cover off I noticed the hot melt glue holding in the by-jesus pin (Called that because of mechanics saying, "it'll hold, by Jesus!") Well, it didn't. And 5 miles from home, uphill :veryangry: Digging through the sack of bolts we ALL should be carrying I found a tiny metric screw, a #3 metric. If you have a hot glued retaining pin(the by-jesus pin) pull it out and screw in the #3 metric. 1/2 inch is long enough. The hole is just big enough for the screw to self tap and enough hot glue is left to act as a screw locker.

    As far as filters go that's a good one. The glass is tempered for strength and fairly thick to resist breakage and has a huge(for a MTB) surface area for long life. I never got to use my stock filter. After finding out how chump the stock fuel line is(brittle fuel line...)I walked the 1/4 mile to the MotoTech motorcycle dealer down the street and got a new hose. I thought about a filter but went naaaa. I went to install the hose and when I picked up the filter it rattled :p Back to MotoTech. The filter I got is like a flat pancake with a stainless steel screen, ultra fine. :cool: And clear so you can see any :poop: buildup.
  8. Fletch

    Fletch Member

    I noticed that glued in pin too, but kind of just put it in the back of my mind because there seems to be enough on these HT's to go wrong as it is to keep me busy! :sweatdrop:

    That's a great tip on the screw replacement though for the clutch arm. That should be in a sticky or added to the list of things to do on a new build. These things definitely aren't as easy as taking them out of the box and slapping them on a bike.
  9. motorpsycho

    motorpsycho Active Member

    the things about the fuel filter giving "great flow" is a bot of a misconception.
    sure, as long as the filter is not plugged it will flow great. but no matter what filter you have on there, the filter will only flow as much as the fuel line will allow in and out of the filter.
    no matter if you have a fine screen filter, or no filter at all, the volume of flow will still be the same because of the 1/4" fuel line. when an engine is running, the needle & seat is opening and closing constantly to allow the float bowl to stay full at all times. as soon as the fuel level drops enough to open the needle & seat, fuel will flow into the bowl. If your float is adjusted correctly, this is how it shoudl work. if your float bowl gets 1/2 way empty and then the needle & seat opens, this is when your carb can run out of gas even tho you have fuel flowing into it. the engine will suck up the gas from the bowl faster than gravity can re-fill the bowl.
    so really, fuel flow can only be so good on these engines because of the small diameter gas line. remember, gravity is feeding the fuel to the carb, not a fuel pump like on a car.
    you are relying on gravity to feed the fuel. You want minimal bends in the fuel line, an un-plugged filter, and a correctly set float level.
    1/4" fuel line will only flow so much fuel, so the filter has very little to do with the flow rate, unoless the filter is plugged solid.
  10. motorpsycho

    motorpsycho Active Member

    that pin should be epoxied in, not hot glued in. if yours was hot glued, then i would not trust anything on that engine.
  11. Dave C

    Dave C Member

    ...what makes you think yours is held in by epoxy?
  12. motorpsycho

    motorpsycho Active Member

    because i can tell the difference between epoxy and hot glue.
    hot glue is still soft when dry, epoxy is hard when it's dry. besides that, the epoxy holding my pins in on both of my engines is gray.
    I don't know of any hot glue that is gray in color.
  13. Bob Mac

    Bob Mac Member

    inline gas filter

    Another thing to look at is the petcock on your tank. If your using the petcock that comes with the kit their are 2 little screws on the side of it. Take those out (when the tank is empty) and remove the leaver you will see that their's 2 little holes where the gas flows thru. Make sure the 2 holes are open. On mine, one of the holes was blocked with a paint chip severly restricting the flow. Just adding my 2 cents:idea:
  14. Fletch

    Fletch Member

    I don't think mine is plugged but I will do. I drilled the opening (gas In side) of the petcock wider the other day. The hole was really small there. I have 2 other petcocks lying around. I looked and they have different size holes too. One is smaller like the one I drilled. That might be something to look for too.

    I honestly didn't know there were holes inside the petcock where lever is. Maybe I will widen those too?

  15. motorpsycho

    motorpsycho Active Member

    Again, you guys are not following what i'm saying.
    You could have a 3 inch diameter hose, tapered down to the 1/4 inch hose of the fuel line, and the end result will not flow any better. A 3 inch hose obvioulsy will flow a lot more fuel that a 1/4 inch hose will, but by the time the fuel gets to the 1/4 inch hose, the flow rate will be reduced.
    Gas is never actually flowing constantly in the fuel line.
    It's an "on-off" effect due to the float opening and closing the needle & seat.
    As long as you can keep the gas line and the filter full of fuel, your float bowl should never run out of fuel.
    The flow that you guys are after is only good until the fuel line and float bowl are full.
    when those 2 things happen, no fuel is moving in the fuel line. Fuel only moves, or flows, when the needle & seat are opened, and when that happens, it's only for a fraction of a second.
    so having high flow really won't gain you anything as far as performance goes. It will gain you the ability to fill an empty float bowl(like after your bike has been sitting all season) but again the flow will be limited by the 1/4 inch fuel line. your engine won't start until the float bowl is at least 1/2 full anyway. so why go through all of the troubel trying to increase fuel flow?
    it's not like high flow in this case will supply more fuel to your engine.
    Last edited: Feb 14, 2011
  16. Fletch

    Fletch Member


    I understand completely that there is going to be a bottleneck somewhere. Don't you still want everything as openly flowing as possible? I'm not following you on the 3" to 1/4" hose. I have a black hose with 1/4 i.d. and I'm guessing a 1/2 o.d. (the kind that comes with the 2010 grubee kits and you can get at the auto parts store. It runs all the way from the petcock to the carb inlet. If I take the hose off the carb and let the fuel flow freely, it does not fill the entire 1/4 i.d. of the hose. I'd guess maybe the "stream" is 1/8". Doesn't that mean there is room for more flow inside the line? My fuel filter is filling up, so I doubt it is a problem. I was running out of gas on monster hills before, but I changed a few things (filter one of them) and now I don't run out. I understand that increased flow won't improve performance because the inlet on the carb and the float only allow so much in. I'm just shooting for THAT to be the bottleneck and never running out of fuel because of a slow flow higher up (be it petcock or filter). I've got a larger carb coming and I just want to make sure I have optimal flow all the way down to the fuel inlet on the carb. I think I'm on the same page as you. I realize there is no added performance. Also I figure the higher the flow to begin with (up to the 1/4 inch max on the hose), the more room for minor flow slowing due to eventual filter clogging etc. Keep in mind I was running out of gas on huge hills that were probably at least 1/2 mile long. So all that fuel in the bowl, plus the fuel in the filter and hose was being used up after say 1/4 mile for sake of discussion (I have no idea the actual time). Once the bowl, filter, and hose were empty, that is/was when the actual flow down the hose mattered because it just wasn't getting to the carb quick enough to keep from stalling. This is just my theory and I'm not an expert by any means. I'm just following the chain of events. Feel free to correct me if I'm still missing something. Thanks
    Last edited: Feb 14, 2011
  17. motorpsycho

    motorpsycho Active Member

    I'm not saying that there is anything wrong with trying to open everything up so the gas flows as freely as possible.
    what i am saying is that no matter whet you do, the volume of gas that will flow will always be limited by the size of the gas line.
    even if your gas flow is a trickle, it would still be enough to keep the fuel line and filter full enough to fill the float bowl. once the fuel line qand filter are full, there is enough gas there to keep the float bowl topped off. as soon as ther float drops and opens the needle and seat, a trickle of gas will be enoiugh to re-fill what little fuel was drained from the line into the float bowl.

    The object isn't to get gas into the float bowl quickly, it's to get the correct volume of gas into the line and filter to keep the bowl full.
    What i meant by the 3" hose to 1/4" hose is that if you have a nice big free flowing 3 inch hose (assume this is the gas tank petcock) and then you stick a 1/4 " hose on it the flow will be greaty reduced.
    so, if you open everything up and make it flow as freely as possible, the small diameter fuel line will only be able to flow so much fuel.

    I guess what i'm trying to say is that fuel flow may not be as important as fuel volume. since the fuel in the line does not flow all the time (again, the on & off effect) it's more important to be able to keep the line and the filter full of fuel than it is to try and increase the amount of flow. again, the fuel volume is still limited by the size of the petcock opening. so even if you get the petcock all opened up, burrs removed and all that, the flow will still be restricted due to the size of the outlet where the fuel line goes.
    And then there is the inlet on the carb., which is small too, so it will cause another restriction in flow because of it's small size.
    even if you do increase the flow (for example) from 1 gallon per minute to 3 gallons per minute, the float will close the needle & seat, causing all fuel flow to stop once the float bowl is full.

    You need to think of the fuel system as a strobe light and not a garden hose.
    With a strobe light you can increase and decrease the strobes(the amount of time that the light goes on and off) with a potentiometer. doing this will speed up or slow down the strobes, but it will not make the light brighter. It will lengthen or shorten the amount of time that the light is on and off. I'm using this example to show that you can increase the volume, and not increase the flow because of restrictions.
    think of the volume in this case as the time that the light is on or off, and think of the flow as the brightness of the light. the "flow" is limited by the amount of power that the light uses. the volume can be increased or decreased by creating more or less resistance.
    Maybe i'm misunderstanding what you are trying to achieve?
    Am i going into this too far?
    Last edited: Feb 14, 2011
  18. Fletch

    Fletch Member

    No we're on the same page ;) I'm not trying to achieve anything. When I was starving for fuel on one specific mountain road after a certain distance of WOT, the fuel flow was the first suspect though. When it is WOT constant for minutes up a windy mountain road there is no strobe light effect. The light is constantly on. That's when (like you say) the fuel can only travel as fast as the hose will allow... But if it is impeded at that point to be less than the hose can allow, then there comes a point where all extra fuel in bowl, filter, and hose are used up and the main jet sucks dry and chokes out. Of course gearing plays a role too in climbing hills. If my sprocket was still a 44 and not a 41 for instance...maybe I wouldn't have run dry? Plus the expansion exhausts consume more fuel than regular. There are many factors at play and I'm just saying it's good to have the maximum flow the hose will allow.
  19. motorpsycho

    motorpsycho Active Member

    yes, that makes sense.
    but i doubt that there is ever a point where the fuel flow is constant because the engine can not use up gas faster than it can be supplied. these things don't burn that much fuel even when at w.o.t.
    in some instances, i can see where the flow would not be fast enough to fill the bowl back up, but i think that the flow would have to be reduced to a trickle for that to happen.
    I have also seen where an engine will run out of gas at w.o.t. because the carb is at an angle instead of being level.
    but what you are saying makes sens, and i agree that you shoudl try to get the fuel to flow as freely as possible.