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Thread: CB250RS air filter where to buy

  1. #16
    Join Date
    3rd April 2019 - 19:24
    Bike
    2004 Suzuki GN250
    Location
    Auckland
    Posts
    28
    Cheers all,

    Looking to make one my own from some this foam : https://pararubber.co.nz/product/filter-foam/ . Looking at the 45PPI stuff and got 31cm x 12cm x 12mm, adding an extra CM to the W and L just in case.

    Btw, dimensions taken from my original perished filter are 30cm x 11cm x 1.2cm approx.
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  2. #17
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street 765RS/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
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    18,711
    Ummm.. . That looks like filter foam for fish tanks. I'd want to try a bit soaking in petrol and dried out first.


    Ok found para add

    Filter Foam Large Pore


    CategoriesCommercial Foams, Residential Foams, Speciality Foams


    Filter Foams have a very precise open pore structure. PPI is pores per inch, so the higher the PPI, the finer the particles that will be filtered.
    25 PPI
    Large pore is useful for gutters and ponds
    Foam cut to size cannot be returned or exchanged



    No thanks
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  3. #18
    Join Date
    3rd April 2019 - 19:24
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    2004 Suzuki GN250
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    Auckland
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    28
    I believe the photo is more of a placeholder on their website, I'll be going in to pararubber out of lockdown to see what its like in person. If it aint suitable, Im sure they'd be able to point me in the right direction.

  4. #19
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street 765RS/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
    Posts
    18,711
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  5. #20
    Join Date
    3rd February 2004 - 08:11
    Bike
    1982 Suzuki GS1100GK, 2008 KLR650
    Location
    Wallaceville, Upper hutt
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    4,596
    The ad seems to imply that the size of the hole in the foam determines the size of particle that will be trapped (or passthrough). I always believed that the foam was a just a carrier that the filter oil could cover, and that the oil would trap the dirt. Obviously it has to be open cell so there is a path for air to get from one side to the other but, in the end it is the oil that does the filtering. During my time working on Cat tractors, the oil bath filters used wire mesh - pretty open - to hold the oil. The level of oil was just below the bottom of the mesh and would splash up due to machine movement. The other part of the filtering was that the intake air was drawn down the centre and then turned up into the mesh- the heavier particles of dirt went straight down into the oil and were trapped, Oil bath filters only went out of favour because of the high maintenance (wash out every day in very dusty conditions) they required vs paper element filters, which, when coupled with a cyclonic pre-cleaner, were as effective
    it's not a bad thing till you throw a KLR into the mix.
    those cheap ass bitches can do anything with ductape.
    (PostalDave on ADVrider)

  6. #21
    Join Date
    1st February 2004 - 11:00
    Bike
    MG V11 Nero Corsa LeMans
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    out west a chch
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    Quote Originally Posted by F5 Dave View Post
    FFS... dearer than buying the right thing... again I post...https://www.uniflow.com.au/contents/...hondaroad.html
    I have that link cos I need one for the turb... its a no brainer
    cheers DD
    (Definately Dodgy)



  7. #22
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street 765RS/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
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    18,711
    Ooh, Trumped.

    He could make a few with the sheet, but with postage from aus that could well be cheaper. Good find.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  8. #23
    Join Date
    3rd April 2019 - 19:24
    Bike
    2004 Suzuki GN250
    Location
    Auckland
    Posts
    28
    Both are good options! Both are good foam. Now to decide where the pennies will fall Haha Trouble with older bikes, there's always more to buy

  9. #24
    Join Date
    3rd April 2019 - 19:24
    Bike
    2004 Suzuki GN250
    Location
    Auckland
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    Quote Originally Posted by pete376403 View Post
    The ad seems to imply that the size of the hole in the foam determines the size of particle that will be trapped (or passthrough). I always believed that the foam was a just a carrier that the filter oil could cover, and that the oil would trap the dirt. Obviously it has to be open cell so there is a path for air to get from one side to the other but, in the end it is the oil that does the filtering. During my time working on Cat tractors, the oil bath filters used wire mesh - pretty open - to hold the oil. The level of oil was just below the bottom of the mesh and would splash up due to machine movement. The other part of the filtering was that the intake air was drawn down the centre and then turned up into the mesh- the heavier particles of dirt went straight down into the oil and were trapped, Oil bath filters only went out of favour because of the high maintenance (wash out every day in very dusty conditions) they required vs paper element filters, which, when coupled with a cyclonic pre-cleaner, were as effective
    Interesting what you say Pete. The CB250RS has a sealed airbox besides the snorkel out the top (hidden under seat), inside there's a double layered fine mesh element and then usually oiled foam over this. Being that at one stage I was thinking of pulling it all out and replacing it with a velocity stack/bell mouth, I wonder if there's really much harm running it with just the mesh which is enough to stop grit, but not dust. Sure Im aware on small engines particularly this can introduce fine wear and tear to the carb and engine. But with the roads I ride and the few KMs I put on this bike each year, I do wonder. See plenty of big old bikes with bellmouths on their carbs. How about a bellmouth with a bit of oiled stocking and a rubberband Haha Anyone?
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  10. #25
    Join Date
    3rd February 2004 - 08:11
    Bike
    1982 Suzuki GS1100GK, 2008 KLR650
    Location
    Wallaceville, Upper hutt
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    When I bought my first speedway bike (J.A.P motor) the air intake was a large bell mouth and the airfilter was a piece of nylon stocking. That would have kept small stones out. The actual filtration was grease smeared on the inside of the bellmouth. It was expected rings would be changed every few meetings, pistons once or twice a season. As I never had anywhere near that kind of money, I put on a K&N filter (oiled cotton between layers of gauze) and the engine lasted all season.
    Whether you feel you can get away without a filter depends on where you ride. Pay your money and take your choice
    it's not a bad thing till you throw a KLR into the mix.
    those cheap ass bitches can do anything with ductape.
    (PostalDave on ADVrider)

  11. #26
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street 765RS/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
    Posts
    18,711
    And more to the point, changing the airbox or filter will muck up the jetting and correcting that won't just be a case of buying a bigger main jet.

    Keep std airbox assembly and enjoy a better running bike.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  12. #27
    Join Date
    25th March 2004 - 17:22
    Bike
    RZ496/Street 765RS/GasGas/ etc etc
    Location
    Wellington. . ok the hutt
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    Quote Originally Posted by jmpl View Post
    Interesting what you say Pete. The CB250RS has a sealed airbox besides the snorkel out the top (hidden under seat), inside there's a double layered fine mesh element and then usually oiled foam over this. Being that at one stage I was thinking of pulling it all out and replacing it with a velocity stack/bell mouth, I wonder if there's really much harm running it with just the mesh which is enough to stop grit, but not dust. Sure Im aware on small engines particularly this can introduce fine wear and tear to the carb and engine. But with the roads I ride and the few KMs I put on this bike each year, I do wonder. See plenty of big old bikes with bellmouths on their carbs. How about a bellmouth with a bit of oiled stocking and a rubberband Haha Anyone?
    The last time I saw one of those I nearly set fire to it with some engine start spray and a backfire. Put that out with a rag before it could do any damage. We got the bike going eventually. Heck was Cathy's (for those that remember CSL) Geez that must have been 15 years ago.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  13. #28
    Join Date
    23rd August 2021 - 20:52
    Bike
    '81 Honda CB250RS
    Location
    Auckland
    Posts
    4
    Sorry, haven't looked at KB for a while.
    jmpl - I got this for my RS250. This is probably enough for 2 filters. I've installed it but haven't properly tested. Have bought a few things from this company so they seem legit enough.

    This foam does seem a little thicker than what its meant to be (protrudes beyond the lip of the mesh filter core), possibly hits the back wall of the airbox and blocks the airflow there? not too sure.
    If you want to be sure then as people have said anaconda will probably have one, or import from UK.

  14. #29
    Join Date
    3rd April 2019 - 19:24
    Bike
    2004 Suzuki GN250
    Location
    Auckland
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    28
    Quote Originally Posted by matthewb77 View Post
    Sorry, haven't looked at KB for a while.
    jmpl - I got this for my RS250. This is probably enough for 2 filters. I've installed it but haven't properly tested. Have bought a few things from this company so they seem legit enough.

    This foam does seem a little thicker than what its meant to be (protrudes beyond the lip of the mesh filter core), possibly hits the back wall of the airbox and blocks the airflow there? not too sure.
    If you want to be sure then as people have said anaconda will probably have one, or import from UK.

    Cheers for getting back to me, no worries at all. Currently deep in engine rebuild so will check out my foamy options once that's all buttoned up

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