CB250RS air filter where to buy

[matthewb77]

Anyone know where I can get an air filter (just the foam element) for a CB250RS in NZ?
Part #3 here: https://www.cmsnl.com/honda-cb250rs-1980-a-england_model16355/partslist/F17.html

What are people's experiences with things like this (https://www.moto1.nz/products/twinair-dual-stage-air-filter-foam-sheet-bulk-air-filter-foam-250x350x15mm) to make your own filter? Are they really any different to a bit of old couch cushion or whatever?

[F5 Dave]

Yes you superglue the sheet together.
And it is different from normal furniture foam. As I found out when I was 17. :facepalm:

[FJRider]

... What are people's experiences with things like this to make your own filter? Are they really any different to a bit of old couch cushion or whatever?

If you change the type and/or structure of the air filter ... you also may change the fuel-air mixture formula arriving in the combustion chamber.

A too lean or too rich mixture can have "Undesirable" results later ... both in performance and engine longevity. Especially on small engines.

If your aim is simply a possible cost cutting measure ... it may save a lot of money by using the correct filters.



Your bike ... your money ... your choice.

[F5 Dave]

Recently I used some unifoam from the local bikeshop to make a filter I couldn't get. It worked well. But dont try just anything.

[matthewb77]

Thanks - I would buy a real Honda filter but I can't find anywhere that sells them locally and would rather not spend copious amounts on importing one from the UK, plus that'd take ages to get here.
I'll avoid the furniture foam and get some of that DIY filter stuff. I'm planning on doing a plug chop once its all woffed and ready so I'll know if the mixtures wrong.

[jellywrestler]

Recently I used some unifoam from the local bikeshop to make a filter I couldn't get. It worked well. But dont try just anything.

para rubber in petone stocks filter foam

[jellywrestler]

Thanks - I would buy a real Honda filter but I can't find anywhere that sells them locally and would rather not spend copious amounts on importing one from the UK, plus that'd take ages to get here.
I'll avoid the furniture foam and get some of that DIY filter stuff. I'm planning on doing a plug chop once its all woffed and ready so I'll know if the mixtures wrong.

have you tried Anaconda?

[FJRider]

Thanks - I would buy a real Honda filter but I can't find anywhere that sells them locally and would rather not spend copious amounts on importing one from the UK, plus that'd take ages to get here.


So ... none of the Honda shops in Auckland are interested in "finding" one for you ... :blank:


Very odd ... :scratch:

[merv]

As Jellywrestler has said above have you tried Malcolm at Anaconda - he has a lot of Honda spares.

https://www.anacondaltd.co.nz/home/

[tigertim20]

Thanks - I would buy a real Honda filter but I can't find anywhere that sells them locally and would rather not spend copious amounts on importing one from the UK, plus that'd take ages to get here.
I'll avoid the furniture foam and get some of that DIY filter stuff. I'm planning on doing a plug chop once its all woffed and ready so I'll know if the mixtures wrong.

Thats odd. Ive found the UK to be one of, if not the fastest international shippers, and ive bought from just about bloody everywhere!

theres a few specialist 'classic' parts suppliers over there, have you looked into them?

[matthewb77]

I've just ordered some of the foam filter stock online from NZ.
I saw a couple of UK websites with filters and its true I don't know the shipping situation for them. though my father has ordered quite a lot of BSA parts from UK 'classic' bike suppliers which always take ages to turn up.
Anaconda would have been a good idea but a bit late now, I'll remember that if there is a next time.

Thanks!

[dangerous]

Anyone know where I can get an air filter (just the foam element) for a CB250RS in NZ?
https://www.uniflow.com.au/contents/en-us/d84_hondaroad.html

[jmpl]

I've just ordered some of the foam filter stock online from NZ.
I saw a couple of UK websites with filters and its true I don't know the shipping situation for them. though my father has ordered quite a lot of BSA parts from UK 'classic' bike suppliers which always take ages to turn up.
Anaconda would have been a good idea but a bit late now, I'll remember that if there is a next time.

Thanks!

Hiya Matthew, just wondering if you could share a link to where you got the filter foam. Im doing an overhaul on my own RS atm and the filter is foam is done.

Cheers, J

[jellywrestler]

Hiya Matthew, just wondering if you could share a link to where you got the filter foam. Im doing an overhaul on my own RS atm and the filter is foam is done.

Cheers, J

para rubber has it

[husaberg]

make your own
The partsfiche sauys its the same as a CM125C or CM250C
https://www.cmsnl.com/products/element-air-clean_17213471010/

[jmpl]

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.

[F5 Dave]

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 (https://pararubber.co.nz/product-category/custom-cut-foam/commercial-foams/), Residential Foams (https://pararubber.co.nz/product-category/custom-cut-foam/residential-foams/), Speciality Foams (https://pararubber.co.nz/product-category/custom-cut-foam/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

[jmpl]

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.

[F5 Dave]

Too easy

https://www.trademe.co.nz/a/motors/car-parts-accessories/performance/air-filters/listing/3233477784?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM46NZbP9 wDsKWDa1ZOFkAvGWQpcZyLp8bo4E1C1-zGqacBXkuLSEHIaAn9iEALw_wcB&gclsrc=aw.ds

[pete376403]

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

[dangerous]

Too easy

https://www.trademe.co.nz/a/motors/car-parts-accessories/performance/air-filters/listing/3233477784?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM46NZbP9 wDsKWDa1ZOFkAvGWQpcZyLp8bo4E1C1-zGqacBXkuLSEHIaAn9iEALw_wcB&gclsrc=aw.ds

FFS... dearer than buying the right thing... again I post...https://www.uniflow.com.au/contents/en-us/d84_hondaroad.html
I have that link cos I need one for the turb... its a no brainer

[F5 Dave]

Ooh, Trumped.

He could make a few with the sheet, but with postage from aus that could well be cheaper. Good find.

[jmpl]

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 :msn-wink:

[jmpl]

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?

[pete376403]

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

[F5 Dave]

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.

[F5 Dave]

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.

[matthewb77]

Sorry, haven't looked at KB for a while.
jmpl - I got this (https://www.moto1.nz/products/twinair-dual-stage-air-filter-foam-sheet-bulk-air-filter-foam-250x350x15mm) 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.

[jmpl]

Sorry, haven't looked at KB for a while.
jmpl - I got this (https://www.moto1.nz/products/twinair-dual-stage-air-filter-foam-sheet-bulk-air-filter-foam-250x350x15mm) 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 :)