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XsP relay.jpg I'm about to take the project out and about for the first time. But.. I'm air filer challenged. The electrical system required not just three micro flashers.. two main fuses links.. but a series of relays...which meant... space..in this case.. stock air boxes... was needed.
I need a small foam filter.. heard too many ugly stories about those pleated paper units.
 
Why so many relays? Did you know that one relay can perform more than one function? Like, you have about 30 circuits that need a relay? So, how many circuits can your bike possibly have? Sorry if this sounds harsh, just don't understand.

Scott
 
The buddy who wired the complete bike... needed relays to properly activate the siren and lights…. visit " xs 650 P " project in the " club house " section.
 
The UNI filters are what most of us use, but I'm not crazy about their short version with the end cap. A local guy installed them and we didn't need to re-jet at all. That tells me they weren't flowing much, if any more than the stock airbox. I prefer the 4" long versions, not only for the increased size but also because the ends are not capped. They draw air both through the sides and in through the ends.
 
I am at this point currently also. Working on a '78 standard E model, carbs totally clean and back to stock jetting. I have a set of earlier '75 airboxes I was thinking of using, but obviously want to put some kind of filter in there. Stock? K&N? In a different situation than motormike with the space crunch, but similar need. As some have indicated, the airbox does help support the carb, but in his case not an option.

Should I bail on this tack, and go individual filters as you indicate? The bike did have little short UNI filters with a chrome end cap, but one has all but disintegrated so unusable. Will need to replace both. Mikesxs does not supply these (UNI). Who supplies? Bike Bandit? Partzilla?

I went to the 650rider site page suggested in one of the threads from here, but no photos anymore so not real sure what I am doing to the airbox 650john is working with/talking about. Anyone done that who could post up a pic?

Not meaning to hijack the thread motormike! I think you will be forced into individual filters that don't impinge on your relay bank.
 
One of the easiest and best (cheapest) places to find the UNI filters is Amazon. The 4" long, open ended Uni you'll want for the BS38 carbs is the UP4200 .....

https://www.amazon.com/Uni-Filter-UP4200-Universal-Urethane/dp/B000OO0X9A

As long as you retain the metal shrouds over the intake manifolds, you will have no carb support issues without the airbox. I've run nothing but pods on my '78 since I got it running back in 2005. I've had no problems with the manifolds.

1GjnNlo.jpg
 
I have these filters as seen in the above photo. Problem is.. to long.... they press against the bank of relays.. I found some foam filters.. without the hard plastic collar.. just foam with a internal spring..... and hose clamp....nice.. I can cut to the desired length... found them on ebay.. from " down under "'... but.. with shipping... yikers.. &80.oo... Wednesday I'll visit mDuk red.jpg Duk red 3.JPG y buddies shop and see what he can order.
The filters shown above.. I've used for years... no end cap... :) .. have no issues with them.... On my 350 Ducati street racer... I use a microphone wind sock.
 
Maybe you could fab a pair of thin, wedge/triangulated air filters. Using 1/4" wire screen (animal cage stuff) as the framework. UNI sheet wrapped over the framework, another layer of wire screen over that, sandwiching the filter sheet.

Can you visualize it?
I'm waving my arms here describing it... :D
 
One of the easiest and best (cheapest) places to find the UNI filters is Amazon. The 4" long, open ended Uni you'll want for the BS38 carbs is the UP4200 .....

https://www.amazon.com/Uni-Filter-UP4200-Universal-Urethane/dp/B000OO0X9A

As long as you retain the metal shrouds over the intake manifolds, you will have no carb support issues without the airbox. I've run nothing but pods on my '78 since I got it running back in 2005. I've had no problems with the manifolds.

Thanks 5TWINS for that info and the pic. What kind of breather assembly is the filter hiding there? Looks like the breather hose from the top-rear of the cam cover is going to a PCV of some kind?

And yes, @M, I can indeed see you waving your arms around! I do a lot of that myself some times!:laughing:
 
PCV valves don't work for this application. They contain a metal ball check valve and it can't move fast enough to keep up with the engine's pressure pulses. What we use is a power brake check valve. It has a rubber flapper valve and can keep up. You can get them right at the auto parts store for about $5. Positioned over the filter, if any oil does come through, it will just drip into the filter. I've never seen any come out of mine.

NM4t1Dh.jpg


The larger "intake" end of the valve is a perfect fit into the stock breather hose. If your breather hoses are original, I recommend replacing them. You'll find they're hard as a rock. One of the good things MikesXS sells is replacement breather hose. It's the same exact size as the original stuff, or at least it used to be.
 
I have added both the UNI filters and the power brake valves to the bike. Carbs cleaned & synched with mercury sticks. But after a 30 mile ride this was my plug check pic. I'm thinking I need to go bigger on the main, pilot as well? Would raising the needle be enough?
 

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It is pretty much impossible to tell what needs changing, if anything, just based on that pic. To get an idea about main jet from reading plugs, you need to run WFO for some distance, then shut down the engine at high rpm, and coast/brake to a stop. The needle position and pilot jet size/mixture screw adjustment is more of a "feel" thing, like how it takes throttle from idle, and how it cruises at a steady speed and accellerates. My personal impression is that your plugs are quite sooty at the end if tbe thread, so it is most likely rich at whatever carb circuit was most active during your 30 miles, or at the end of that trip.
 
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