[mcplorer]

Hello everyone,

I am new to this forum and this is my first post. I own a Classic350 (UCE) 14500kms on ODO. I guess this would be my first major mod. My bike runs on short bottle muffler and no cat-con in bend pipe. Now I am planning to fit UNI air filer and re-jet the BS29 stock carburetor. I need few things to know before going for it:

1. How is the UNI filter as compared to K&N considering dusty conditions. I am more inclined in using UNI
2. What is the size of the air-intake side of the BS29 carburetor. I need to know this so that I can get to know which UNI would fit into the BS29
3. What should be the jet sizes after fitting UNI and the needle position
4. How much performance gain can I expect. I know this cannot be calculated plain simple by just putting it and guessing but then roughly how different the throttle response would be.

Thanks in advance

[ace.cafe]

 I haven't used the UNI filters on the Bullet. My past experience with them was not too good. I don't think that they flow very well. Not as good as a K&N from what I have seen. I wouldn't count on any performance increase from a UNI filter.You could get a performance decrease.

I have become a big fan of pleated paper filters. If you get the right one for the application, they flow at least as well, or better than washable filters,  and they filter the air a lot better.

Anyway, sorry I couldn't give you a direct answer about the UNI.

[mcplorer]

Hey thanks a lot Ace for such quick reply. Actually I stay here in India and the conditions are a bit dusty here hence UNI is recommended as K&N suck lot of dust as well.

Btw can you throw some light on the other questions which I asked like jet sizes etc? And what do you think about VM flat slide or round slide carbs?

[ace.cafe]

Hey thanks a lot Ace for such quick reply. Actually I stay here in India and the conditions are a bit dusty here hence UNI is recommended as K&N suck lot of dust as well.

Btw can you throw some light on the other questions which I asked like jet sizes etc? And what do you think about VM flat slide or round slide carbs?

I can shed some light on the Mikuni  flat slide jetting starting points. I don't use the CV carbs.
The flat slide Mikuni TM32 will use a 30 pilot, P4 needle jet, 195 main jet, at sea level in average temps. If you are at higher elevations, the jets need to go leaner, depending on the altitude.

People in the AVL forum probably can advise you on the BS29.

[mcplorer]

OK. Thanks again Ace and I might bug you if I am going for flat slide Mikuni TM32 ever

[High On Octane]

I agree with Ace about the air filter.  I have used UNI filters in the past on my dirt bikes, but I also heavily oil them as they were 2 strokes.  Oiled filters don't work well on 4 strokes as it is important to keep things clean as possible in the intake and combustion areas.  A standard pleated paper filter does a much better job of cleaning the air than a "performance" filter.  Being that you live in India and things are very sandy and dusty (from what I've heard ) I think good filtration is more important than the tiny 1/2 HP increase that you MIGHT see.

Scottie J

[mcplorer]

Thanks for the input mate.
So do you have the same view if one uses K&N instead of UNI?

And yes conditions are indeed a bit dusty here in India

[barenekd]

Don't worry about seeing a 1/2 horse increase with a Uni. It'll never happen, You will probably need to go down one jet size if you decide to use one. Paper or K&N are a better choice for performance.
Bare

[mcplorer]

You will probably need to go down one jet size if you decide to use one. Paper or K&N are a better choice for performance.
Bare

I am sorry but what makes you think so?  . Few guys whom I know here are using UNI and they indeed had to up-jet . So you think UNI sucks air poorer than stock paper element air filter?

[ace.cafe]

I think a general consensus is developing here that a good pleated paper element of the proper size and filter area will flow better and filter dust better. Washable filters get a lot of marketing push, and can be handy to wash instead of buying new, but at the end of the day, I feel it is difficult to beat a properly implemented pleated paper filter.

Perhaps look into the largest good quality pleated paper filter element which can fit into your stock airbox, and make sure that the airbox is well sealed from dirt ingress.

[ERC]

Ace is correct on that one.  ERC

[mcplorer]

I think a general consensus is developing here that a good pleated paper element of the proper size and filter area will flow better and filter dust better. Washable filters get a lot of marketing push, and can be handy to wash instead of buying new, but at the end of the day, I feel it is difficult to beat a properly implemented pleated paper filter.

Perhaps look into the largest good quality pleated paper filter element which can fit into your stock airbox, and make sure that the airbox is well sealed from dirt ingress.

Thanks a lot Ace for that ace comment  . Something to be brooded over before going for the mod.

[barenekd]

I am sorry but what makes you think so?  . Few guys whom I know here are using UNI and they indeed had to up-jet . So you think UNI sucks air poorer than stock paper element air filter?

I used to work in a Triumph, BSA, Norton shop and for awhile we replaced the stock paper filters with UNIs. I ran across several occasions that the UNIs would choke the engine down to the point that they wouldn't even rev out from being too rich. We quit using the UNIs. I'm not impressed.
I personally far more impressed with K&Ns which I have used on many bikes over the years.
People on this forum degrade them because the holes are bigger in them than the paper filters which is true WHEN THEY ARE DRY. Once the oil is applied the hole size shrinks down the near the paper size and, ban by my experience stop as much foreign particulates as do the paper filters.
Bare

[mcplorer]

I personally far more impressed with K&Ns which I have used on many bikes over the years.
People on this forum degrade them because the holes are bigger in them than the paper filters which is true WHEN THEY ARE DRY. Once the oil is applied the hole size shrinks down the near the paper size and, ban by my experience stop as much foreign particulates as do the paper filters.
Bare

Thanks for the comments Bare. So how often you need to clean and oil film the K&Ns. Do they require frequent maintenance?

[High On Octane]

When I had K&N's on my street bikes I'd wash and oil them every spring.  If you're insistent on using a K&N in your conditions/environment, I HIGHLY recommend using one of their Pre-Charger Filter Wraps to go over the filter.  I'd also make sure to wash that filter at least twice a year.

http://www.knfilters.com/search/wrap.aspx

For what it's worth.......  I was always a HUGE fan of K&N filters and have sold them to many customers when I was selling auto parts.  But the more I get involved in the performance scene, the more and more people I meet that STAY AWAY FROM K&N FILTERS for the reasons previously stated.  I used to be a Chevy Boy and put K&N's on all my trucks and cars and I never noticed ANY performance gains, though my one truck did run a little smoother at idle.  Now, one of my friends (here in Denver) who has been building Chevy motors with his dad since he was 8 years old swears that K&N's are the Anti-Christ.  My new engine guy/co-worker builds Subaru motors pushing anywhere from 300-700hp at the wheels.  He is convinced that a K&N will do more damage to the motor letting in dirt and oil than beating on the motor on a regular basis with a paper filter.  I personally will never waste my money another one, and I've installed them in 2 different bikes and 4 different cars over the years.  But to each their own.

Scottie J