Moose12
XS650 Member
Hi! I have a 1977 xs 650. Looking to switch over to pod-style air filters. How do I select ones that will fit and work right. Running BS38 carbs.
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Switching to pods
- Thread starter Moose12
- Start date
First off, do not use any of the cheap K&N copies out there. The amount of filtration they offer is poor and many have a large rubber lip on the inner side of the mounting flange that can block the air jets on the intake bell. But there is another more important reason not to run these or even genuine K&N pods. The pleated element style disrupts the air flow which can cause slide lift problems. You won't get the most out of your carbs or the best state of tune if you choose to run this type of pod.
The best pod is a straight foam type. Most of us run the UNI black foam pods. For the BS38s, one with a 2" mounting flange I.D. is what you want. The 4" length will fit between the carb and battery box. Anything longer will not. So, what you want is the UP-4200 or the UP-4200ST (dual layer). There is also a 15° angled version (UP-4200AST) if you need it.
http://unifilter.com/clamp_on.html
A note on oiling - the normal foam filter oil can be too thick for these because the black foam is very fine. It can clog them. Most of us use a 50-50 mix of gas and motor oil.
http://www.uniflow.com.au/contents/en-us/Black foam road bike pods.pdf
The best pod is a straight foam type. Most of us run the UNI black foam pods. For the BS38s, one with a 2" mounting flange I.D. is what you want. The 4" length will fit between the carb and battery box. Anything longer will not. So, what you want is the UP-4200 or the UP-4200ST (dual layer). There is also a 15° angled version (UP-4200AST) if you need it.
http://unifilter.com/clamp_on.html
A note on oiling - the normal foam filter oil can be too thick for these because the black foam is very fine. It can clog them. Most of us use a 50-50 mix of gas and motor oil.
http://www.uniflow.com.au/contents/en-us/Black foam road bike pods.pdf
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angus67
Welder's penetrate deeper!!
i have those foams on my bike as well as on my airbox free 2003 suzuki. they work great, other than sideways airflow from passing big riggs.
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Angus is running one of the PK kits. These are shorter rubber end capped filters and may be what you need if space is limited (like on a hardtail). I should also mention that the BS34s have a larger diameter intake bell so the next larger sized mounting flange (2 1/4") works better. This would be the UP-4229, UP-4229ST, or UP-4229AST. You can stretch a 4200 (2") onto them but it is a very, very tight fit. I would be concerned about the mount splitting eventually.
The shorter PK version kits are the PK-82 (2") for the BS38s and the PK-92 (2 1/4") for the BS34s.
The shorter PK version kits are the PK-82 (2") for the BS38s and the PK-92 (2 1/4") for the BS34s.
Moose12
XS650 Member
Angus, You have any full pics of that bike? That bubble paint job is intriguing! What is that tank down there?
Moose12
XS650 Member
Thatnks 5twins! Super helpful!
YL82
Perpetual Restorationist
I recently bought my 2nd '76C in French Blue. Aside from a non '76 brake master cylinder and a '78-79 stepped seat, it appears to be stock.
Plan to repaint to red scheme, but lots of mods to do before then.
Popped off the side covers today, pulled off the airbox covers and removed the filter cartridges. There was nothing but metal frame left in either filter. Not even a hint of paper, foam, etc. PO's....
I shouldn't be so judgmental. PO wasn't completely neglectful...There is some visible filtration media remaining on the frames. Refer to image.
On my first '76, I eventually removed the factory airboxes and went with 4" Uni (pod) Filters.
Are there any "Airbox Enthusiasts" out there who can convince me to stick with the airboxes and dissuade me from going the Uni-Filter route again? I still have a pair of K&N OEM Type pleated filters (YA-1152) on hand.
I've got a comparable ignition question regarding sticking with points, condensers, etc. (at minimum, I plan to swap out weak coils) and not converting to Pamco, but that's a different thread...
Plan to repaint to red scheme, but lots of mods to do before then.
Popped off the side covers today, pulled off the airbox covers and removed the filter cartridges. There was nothing but metal frame left in either filter. Not even a hint of paper, foam, etc. PO's....
I shouldn't be so judgmental. PO wasn't completely neglectful...There is some visible filtration media remaining on the frames. Refer to image.
On my first '76, I eventually removed the factory airboxes and went with 4" Uni (pod) Filters.
Are there any "Airbox Enthusiasts" out there who can convince me to stick with the airboxes and dissuade me from going the Uni-Filter route again? I still have a pair of K&N OEM Type pleated filters (YA-1152) on hand.
I've got a comparable ignition question regarding sticking with points, condensers, etc. (at minimum, I plan to swap out weak coils) and not converting to Pamco, but that's a different thread...
Attachments
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I like to buy UNI filter material and fit it to the stock filter frames. This works well for me. Yeah the filter frames only is a popular PO trick when the original mouse hair filter material self destructs. (it always does)
YL82
Perpetual Restorationist
Thanks, Gary. The dichotomy of embracing cutting edge filtration technology while merging it with the vintage superstructure appeals to me.
I'll check out their site to look into how the sell their foam material.
Do you use their Uni Filter special sauce?
I'll check out their site to look into how the sell their foam material.
Do you use their Uni Filter special sauce?
No I tend to use light oil, maybe some 10 weight fork oil? I always scratch my head about the oil gas mix advocated, the gas evaporates doesn't it?
YL82
Perpetual Restorationist
Yep. Damn high Vapor Pressure.
If you have K&N airbox replacements, they should work fine. It's only in the pod form that the K&N pleated style causes problems. I would have used the airbox replacements myself if they didn't cost like $90 or something.
I recently bought my 2nd '76C in French Blue. Aside from a non '76 brake master cylinder and a '78-79 stepped seat, it appears to be stock.
Plan to repaint to red scheme, but lots of mods to do before then.
Popped off the side covers today, pulled off the airbox covers and removed the filter cartridges. There was nothing but metal frame left in either filter. Not even a hint of paper, foam, etc. PO's....
On my first '76, I eventually removed the factory airboxes and went with 4" Uni (pod) Filters.
Are there any "Airbox Enthusiasts" out there who can convince me to stick with the airboxes and dissuade me from going the Uni-Filter route again? I still have a pair of K&N OEM Type pleated filters (YA-1152) on hand.
I've got a comparable ignition question regarding sticking with points, condensers, etc. (at minimum, I plan to swap out weak coils) and not converting to Pamco, but that's a different thread...
I like my bike to stay as close to stock appearance as possible. I only change things to increase reliability and safety. Yes, I admit it, I'm an airbox enthusiast
I use stock type foam air filters. I like the fact that the crankcase vents back into the stock air boxes. When I bought my bike, the first thing to be removed was the buckhorn bars, and the second thing was the old stock ignition coils. I ran the first year using points, but used a single dual output Accel coil. I used a 1.2 ohm ballast resistor in series with the 3.3 ohm Accel coil, and both sets of points tied together in parallel.. The second year I changed over to a Pamco ignition. I'm still using the same Accel coil, with the Pamco, but of course, without the ballast resisitor.
For anyone that just loves points and likes to fiddle with them, I say knock yourself out, and keep running points. With a good strong coil, points work just fine.
When I changed over from points to a pamco, I could not detect any difference in performance.
YL82
Perpetual Restorationist
5twins
Well, I thought air had a pair of K&N Airbox filters. I can only find 1 of them.
I damn sure don't remember paying $100 bucks a piece for them. The YA-1152's are still pleated like the pods, but you're saying that's its good that they are not pods.
Well, I thought air had a pair of K&N Airbox filters. I can only find 1 of them.
I damn sure don't remember paying $100 bucks a piece for them. The YA-1152's are still pleated like the pods, but you're saying that's its good that they are not pods.
YL82
Perpetual Restorationist
I like my bike to stay as close to stock appearance as possible. I only change things to increase reliability and safety. Yes, I admit it, I'm an airbox enthusiast
When I bought my bike, the first thing to be removed was the buckhorn bars, and the second thing was the old stock ignition coils. I ran the first year using points, but used a single dual output Accel coil. I used a 1.2 ohm ballast resistor in series with the 3.3 ohm Accel coil, and both sets of points tied together in parallel.. The second year I changed over to a Pamco ignition. I'm still using the same Accel coil, with the Pamco, but of course, without the ballast resisitor.
For anyone that just loves points and likes to fiddle with them, I say knock yourself out, and keep running points. With a good strong coil, points work just fine.
When I changed over from points to a pamco, I could not detect any difference in performance.
I appreciate your comments, rg.
As much as saving $, I'd like to learn how to fiddle with points. Would it be better to go with a 1 dual output coil rather that 2 OEM Style coils if I stay with points ignition? My eyes glazed over after reading your 2nd paragraph
, but I'm sure I can wire them up right eventually. I need to search/read some posts on points ignitions and how to manage them. Videos would be nice.
jd750ace
Front Toward Enemy
I have YA-1152's I paid $52.99 for them through airintakesonline on Ebay. I am missing the tension clips that hold them firmly against the front of the box on their surface seals, so I have a block of closed cell foam that keeps them tight against the face. The original design of the airbox in later models is a "still air" reservoir. The intake hole at the back of the box has a diverter that keeps it from being a straight shot to the filter, as is the case with an open air filter that is not contained in a box. I believe this is why the K&N elements in the airbox don't create the slide lift and flutter issues that appear with the open air pods. I have yet to do it, but I need to replace the foam tape that seals the edges of the access doors on the airbox. I believe the tighter the filter chamber, and the more air that comes through the designed chambers of the box, the better the behavior will be. I can tape up my access doors and change my idle, so she's pulling air pretty good around the doors. It causes some variability in my idle. I'm not opposed to the Uni filters. If I needed to shit-can my airbox due to damage, I would probably run them, but since the bike is pretty much stock and all there, I elected to stay with it.
I noticed a huge difference going from stock ignition to the Pamco, but I did not kill any time trying to get the stock system at full tick, knowing full well I wanted the reliability and reduced maintenance of the Pamco with E-advance.
I'm very pleased with the choices I've made. Staying near stock has been a goal from the start, given that the bike is as much a keepsake as anything, having been in the family since new. I have to decide what to do with the exhaust, which is in poor shape, and I'm going to pull the top and do the cam chain guide in the near future.
I noticed a huge difference going from stock ignition to the Pamco, but I did not kill any time trying to get the stock system at full tick, knowing full well I wanted the reliability and reduced maintenance of the Pamco with E-advance.
I'm very pleased with the choices I've made. Staying near stock has been a goal from the start, given that the bike is as much a keepsake as anything, having been in the family since new. I have to decide what to do with the exhaust, which is in poor shape, and I'm going to pull the top and do the cam chain guide in the near future.
I appreciate your comments, rg.
As much as saving $, I'd like to learn how to fiddle with points. Would it be better to go with a 1 dual output coil rather that 2 OEM Style coils if I stay with points ignition? My eyes glazed over after reading your 2nd paragraph
I need to search/read some posts on points ignitions and how to manage them. Videos would be nice.
I'm not an expert on ignition coils, but I can pass on what I have learned from experience.
The problem with points (besides fiddling with adjustments due to wear) is that they restrict the coil choices to coils with 4 ohms or greater primary resistance.In addition, the original style OEM coils, only produced 13 k volts maximum voltage when they were new. As the coils and spark plug leads aged, the voltage would be even less. Add in some voltage drops through the fuse holders, ignition switch and kill switch, you end up with maybe 10 or 11 volts at the primary and 10k or 11k high voltage. The result is a weak yellow spark, and the engine barely starts and runs like crap.
If you can find 2 single output coils that produce strong voltage, then that could work for you. Keep in mind the 4 ohm restriction.
If you start with a strong coil, such as the Accel 140403S, you could use a ballast resistor, and go with points. That what I did for one year and my engine started and ran extremely well.
Anyone that changes over from the old stock style OEM coils to a Pamco will see a big difference. The main reason is because of the much stronger coil. After using points and my Accel coil for one year, when I changed over to the Pamco sensor with the same high quality coil, I could not detect any difference, because I already had a strong blue spark. The ballast resistor does reduce the spark quality slightly, but with a strong high quality coil, you still have an excellent spark.
The mechanical ATU is problematic, and I was happy when Pete brought out the E-advancer for the Pamco. The E-advancer gives a much smoother and linear advance.
So, yes points and the mechanical ATU both work, but I'm very happy to have left both behind to become museum pieces, and have more time for riding.
I bought some of those cheapies and they do block the air jet openings.... I was doing some custom stuff on my bike and made some tubes that don't block the jets and hopefully give that air some time to smooth out before entering the carbs...
http://www.xs650.com/forum/showpost.php?p=267186&postcount=264
http://www.xs650.com/forum/showpost.php?p=267186&postcount=264
79Standard
XS650 Addict
FWIW I just switched to Uni pods and am glad I did. The cost of replacement filters for the stock airboxes is just about the same as the Unis (UP4200 for BS38s) and a handful of jets. Great excuse to crack open your carbs if it hasn't been done already- I discovered a leaky float when doing mine. There is an excellent carb guide (http://www.amckayltd.com/carbguide.pdf), I highly recommend reading this all the way through before tackling the job. I had never done something like this before, and am glad I did. Feel much more confident tuning/troubleshooting carb issues now.
YL82
Perpetual Restorationist
I have yet to remove, disassemble and clean the carbs on my latest 650, but need to. The familiar odor of stale fuel (varnish, actually) tells me the BS38's need a good cleaning. Yes, that's a great guide. I've got it printed out, tabbed and in a 3-ring binder.
I plan to stick with my airboxes on my latest '76, but will no doubt miss the "wide open spaces" afforded by removal and use of pods.
I know that I'm going to rip out the old Rectifier and make up my own. Not sure whether the boxes will be in the way for removal as much as during installation of a new one (rectifier).
