Uni Air Filter Conversion

Want to make a change that's not just a fix or direct replacement...

Uni Air Filter Conversion

Postby Barbie & Skipper » Sun Mar 08, 2020 2:37 pm

Since it is essentially impossible to find air filters for the VTR 250, I was going to do a K&N 33-2120 air filter conversion on Skipper, like I'd done a few years back on Barbie, but finally decided to try using Uni Filter's foam sheets. http://shop.unifilter.com/c/accessories_foam-sheets

It's hard to find a good flow comparison, but the choices boiled down to the green 65ppi (pores per inch) or the red/yellow 40/60 12x16x5/8 sheets. I was at Cycle Gear yesterday, and the only foam sheets they had were the green ones, so I went with that. I'm guessing the 65ppi flows closer to stock, and the 40ppi flows closer to a typical K&N, but I'm not certain. If I were doing it over, I might order the 40/60 sheet.

The process was fairly straight forward.

First, I cut out the old paper element with a sharp knife and cleaned up the residual paper/glue a bit. I didn't put a huge amount of effort into the cleanup, but did want the sides to be relatively smooth.

Next, I measured the opening, and cut the foam slightly oversize. There is enough foam to cut out 2 VTR filters. I decided on 8 1/2 by 6 1/2 on my first filter and a bit bigger on the second. The 8 1/2 x 6 1/2 fit flat dry, but I had to cut the second one down, as it bulged quite a bit, even dry. I went oversize because I wanted a snug fit without gluing. Even if I were glueing, I'd still probably go a bit oversize. Skipping ahead a bit, the foam bulged a bit after it was oiled, so I would start at 8 3/8 x 6 1/2 the next time.

Since the metal screen is attached along the long edges, but not the short edges, I didn't want to run the risk of air leaking on the ends, so I cut out and glued extra foam strips on the short edges. By doing it this way, the foam is removable for cleaning and re-oiling. I'm not sure how long Uni foam lasts before it needs to be replaced, but figured I s/b able to get several years of use before needing to start over. I used gasket sealant to glue the foam strips in place, and use some spare foam to space them to allow room for the new filter underneath.

As an alternative, even with the foam glued it, it would probably not be that hard to clean and re-oil the foam, and it could be cut out and the process could be repeated if necessary.

Next, I used K&N spray filter oil on the cut-out foam for the filter, and worked it in according to the instructions. As best as I can discover, you can use Uni or K&N filter oil interchangeably on either K&N or Uni air filters.

Once the edge strips were dried/cured in place, I tucked the oiled foam flter in place. As noted above, even after carefully tucking and smoothing, the foam formed a bit of a mound rather than laying flat. My guess is that the oil expanded the foam very slightly. Unfortunately, I forgot to take a pic of the finished product. :oops:

At that point, I bolted everything back together and went for a test ride. The bike seems to be idling and running fine. No bogs, pulls clean to redline, power seems fine. I don't have an O2 sensors, so I don't know if it's running leaner, richer, or the same, but everythings seems great.

I'll attach a few pics.

It wasn't a difficult process. Never throw away an old VTR250 air filter, as the housing is needed to do a UNI or K&N conversion, and new filters are un-available.
Attachments
oiled_foam_sm.jpg
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foam_end_strips_glued in_sm.jpg
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gasket_sealant_applied_sm.jpg
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foam_cut_slightly_oversize_sm.jpg
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paper_removed_sm.jpg
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foam_marked_for_cutting.jpg
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Barbie - 89 VTR250 - 7k+, back on the road after 3 1/2 year vacation
Skipper - 90 VTR250 - 39k+, black & white, back on the road 22 years after first parked
Parts bike - 90 VTR250 - 20k+, "maintained" by idiots
Barbie & Skipper
 
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Re: Uni Air Filter Conversion

Postby squirrelman jerry » Mon Mar 09, 2020 6:37 pm

as far as UNI is concerned, i have a very negative opinion. :( i used one on one of my '86 VFRs, used the uni=branded filter oil, and within 5 years the filter disintegrated into dust, so i'll never use another UNI product. :?

Picture1-12-2020 216.jpg


(photo taken at south mountain park, PHX)
Last edited by squirrelman jerry on Tue Mar 10, 2020 6:03 pm, edited 1 time in total.
At 20 years old i wanted to be an architect; at 50, i wanted to be Harvey Weinstein's penis.
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Re: Uni Air Filter Conversion

Postby Barbie & Skipper » Tue Mar 10, 2020 12:44 am

squirrelman jerry wrote:as far as UNI is concerned, i have a very negative opinion. :( i used one on one of my '86 VFRs, used the uni=branded filter oil, and within 5 years the filter disintegrated into dust, so i'll never use another UNI product. :?



I understand your concern. My take is that air filters should be checked annually, or more often with a lot of mileage. If I can get 4 years (times 2) out out my $17 foam filter sheet, I'll be quite content. Especially considering I can't find paper air filters for the VTR. <EDIT> I've seen a few disintegrated foam air filters (brand unknown), so I was a bit concerned. Not enough not to use foam filters, but enough to be sure to check them regularly for deterioration as part of the maintenance schedule. </EDIT>

Doing another K&N conversion is not out of the question, but I figured the Uni was quicker, easier, and cheaper. The advantage of the K&N conversion is that it should outlast the bike. Both styles need to be cleaned & re-oiled.
Barbie - 89 VTR250 - 7k+, back on the road after 3 1/2 year vacation
Skipper - 90 VTR250 - 39k+, black & white, back on the road 22 years after first parked
Parts bike - 90 VTR250 - 20k+, "maintained" by idiots
Barbie & Skipper
 
Posts: 138
Joined: Fri Nov 16, 2018 5:12 pm

Re: Uni Air Filter Conversion

Postby squirrelman jerry » Tue Mar 10, 2020 6:06 pm

wasn't there a post some time back about adapting a paper filter from a honda civic for use on a vtr ?
At 20 years old i wanted to be an architect; at 50, i wanted to be Harvey Weinstein's penis.
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Location: buffalo, ny

Re: Uni Air Filter Conversion

Postby Janovich » Sun Mar 15, 2020 8:48 am

So how exactly do you know when the VTR airfilter has become subpar?
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Re: Uni Air Filter Conversion

Postby Barbie & Skipper » Sun Mar 15, 2020 6:18 pm

Janovich wrote:So how exactly do you know when the VTR airfilter has become subpar?

The FSM recommends replacement @ 12k miles, or more often if operating in wet and/or dusty conditions.

Does light pass through the filter?

Does the filter appear dirty?

Do you have any performance issues? (reduced mpg, fouled plugs, exhaust smoke, gas smell from exhaust - basically rich running symptoms)

I didn't own a VTR when they were new. The only factory air filters I've seen have been a brownish orange. Does anyone know if they started out that color, or were they white originally? These bikes are 30 years old, but the 3 filters I've seen have all looked about the same (5k, 20k, 30k miles on the bikes). My personal, wild-eyed, guess is that almost every VTR250 (88-90) out there with over 12k miles needs a new air filter, and are probably still on their original filter if under 12k miles. I don't know when factory or aftermarket air filters were last reasonably available, but it's probably been 5-10 years or more.

OTOH, if your bike has no symptoms of running rich or air starvation, I'm not going to tell you you have to replace the air filter.
Barbie - 89 VTR250 - 7k+, back on the road after 3 1/2 year vacation
Skipper - 90 VTR250 - 39k+, black & white, back on the road 22 years after first parked
Parts bike - 90 VTR250 - 20k+, "maintained" by idiots
Barbie & Skipper
 
Posts: 138
Joined: Fri Nov 16, 2018 5:12 pm

Re: Uni Air Filter Conversion

Postby squirrelman jerry » Sun Mar 15, 2020 9:32 pm

normal color is that brownish orange on an oem filter
At 20 years old i wanted to be an architect; at 50, i wanted to be Harvey Weinstein's penis.
squirrelman jerry
 
Posts: 49
Joined: Wed Jan 15, 2020 10:58 pm
Location: buffalo, ny


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