Fuel Filters

Discussion in 'Tech Area' started by bjf, Apr 24, 2017.

  1. bjf

    bjf Member

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    I'm replacing the fuel lines on my CT70. Do I need fuel filters?
     
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  3. MartinM54

    MartinM54 Active Member

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    There are none factory


    Buildin them the old fashion way, one at a time.
     
  4. racerx

    racerx Administrator
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    He's right...and...the original carbs had fine-mesh brass screens inside the bowl inlet. That said, if you're going to ride, clear inline filters can only help. You'll be able to see when there's dirt in the system, before it can reach the carburetor. If you're also a purist, add enough fuel hose to allow temporary removal of the filters.
     
  5. bjf

    bjf Member

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    There were some on my bike but I'm replacing the fuel lines and I cracked the filter that was on there. I'm fine without if that was stock
     
  6. kawahonda

    kawahonda Active Member

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    I used to use fuel filters, but they are honestly more trouble than they are worth in my case. It's not a bad thing if you only have a bike or two, but when you have 8 of them, several of which are twins (which use two fuel filters each), the maintenance overhead becomes severe. And none of them that I've used, are ideal for the 5mm hose. They seem to be very tight which makes installing and removing not as effortless as it could be. I swear that I've nearly broken several just by getting the stock fuel hose off.

    Fuel filters are made to be replaced every so-often, so it's not a "set it and forget it" item. They can clog up over time and you'll see running issues. The clear ones also discolor and can become an eyesore.

    Carbs typically have filters like racerx said. That, or petcocks typically have filters. No need to filter more than once unless you're prepared for the extra maintenance as I've mentioned above.

    Yes, being able to see fuel flow in is kinda neat, but not really necessary IMO. Unscrewing the carb drain (which is dead simple on the CT70) has a similar effect if you want to make sure fuel is making it to the carb.
     
    #5 kawahonda, Apr 24, 2017
    Last edited: Apr 24, 2017
  7. racerx

    racerx Administrator
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    Agreed, it's a judgment call. The OE brass screen is pretty effective and cleanable. If you're running less than 5 gallons of fuel through your bike, per year, there's unlikely to be much dirt...certainly nowhere enough to clog anything, unless you get a criminally-bad batch of fuel.

    IMHO, the external fuel filters (and Tygon fuel hose) are more applicable to modified bikes that see some mileage. Being able to see fuel flow, or lack thereof, on-the-fly can come in handy...like when "reserve" is reached. Plus, modded bikes are likely to run single-inlet carbs & remote petocks, with a single outlet. More room and a single filter is easier to deal with than twin filters on a stocker.

    FWIW, I also wipe down the inside of the tank, at season's end. The white tank liner makes the dirt impossible to miss. That's not directly applicable to many members. However, some may benefit from my experience. I generally run through 10-20 gallons per season. Seems like the tank collects more crap than it did the previous year.

    As for using the bowl drain as a diagnostic tool, when lack of fuel delivery is suspected...standard operating procedure. You just have to be off the bike.

    BTW, draining the entire system via the bowl drain, at least once a year, is a good idea...easy to do, as well. Drain the fuel into a large funnel, lined with a coffee filter and you'll see how much sediment was inside the bowl, if any. You should be draining the system dry as winter storage prep anyway, also a good time to clean the stock fuel screen too.
     
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  8. bjf

    bjf Member

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    Great info
     
  9. ArcticMinibike

    ArcticMinibike Active Member

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    I would add a couple of things that have burned me in the past...

    1. If you add an inline filter, make sure its below the level of the tank exit. I added one to my snowblower once and it was incredibly frustrating trying to figure out why it kept randomly stalling. I had stuffed it up inside the housing and the line went "up hill" at times depending on the angle when in use. Trimming a couple of inches off the line ensured proper gravity feed.

    2. Use the coffee filter funnel when filling the tank to minimize the problem right from the start. That being said, I break this rule all the time because I just want to ride. :)
     
    #8 ArcticMinibike, Apr 25, 2017
    Last edited by a moderator: Jul 17, 2017
  10. racerx

    racerx Administrator
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    That's a damn good idea, stop the problem before it can begin.:thumb: For those among us who fill their tanks from a gas can, EZ & effective.

    I fill my bikes at the pump, so the coffee filter & funnel might be a little...ummm...impractical:3:
     
  11. OLD CT

    OLD CT Well-Known Member

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    I used the coffee filter trick a couple times for oil that I only ran 10 minutes for break in. It works great, but do it while it's still warm to speed up the operation!
     

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