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Thread: Engine Surging/Hunting 2-3 rpm (again)

  1. #11
    Senior Member lunaticfringe's Avatar
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    You NEED a filter on the there dude
    not so sir. when you capitalized "need" one could deduce you are saying "mandatory" or "required". that just isn't the case. each rocker box lid contains a breather check-valve assembly which is a one-way petal valve and to which the breather line attaches. crankcase pressurized air only comes out...it cannot flow into the motor via the valve. i've installed probably 30 buell breather re-route systems and makes no difference if a breather is attached to end of your new hose line or not. if you feel that a small breather enhances the appearance or makes you feel better about the task then please attach one. same goes for "puke bottle". if your XB motor is in sound condition with no internal problems you should have few if any liquids flowing out the breather ports.

  2. #12
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    You NEED a filter on the there dude.
    False. And for those that install a filter with a catch can or plugged hose end, I strongly recommend you remove and clean the filter every once in a while (maybe every 1,500 miles or so).

    The hose has to be vented somehow, just like the original factory design (it was vented back into the air intake). On a filtered breather re-route installation with a closed hose termination (catch can or some sort of plug), that breather filter is the only path for the pressurized crankcase vapor to escape (those breather caps in the rocker covers are indeed one-way umbrella valves as Lunatic mentioned). Although most of the oil/water vapor from the engine will condense and collect at the bottom of the blocked tube or in the catch can, a portion of that oily mist still suspended in vapor is going to try and exit from the only path it has to escape - the breather filter. That same oily vapor is gradually going to saturate the filter and reduce the filter's ability to "breathe". If left unattended the saturated filter will reduce or eliminate the ability for pressurized crankcase vapor to vent.

    In my opinion, the best case scenario if you run a filter and never change/clean it is that you'll someday see an oily mess somewhere around or below where you have your filter located. Worst case scenario is that the over-saturated breather filter element becomes blocked and crankcase pressure is no longer allowed to escape at all and you blow seals or develop oil leaks elsewhere.

    Remember- those filters that everyone tends to use are designed as an "intake" filter, to filter air coming into a car motor valve cover caused by vaccuum. Using it for a breather re-route is the opposite since you're essentially using it as an exhaust filter. Furthermore, you're really not trying to filter air as it was designed to do, but are asking to filter oily vapor. Big difference.

    I think a lot of folks run those filters because they think it's a mandatory part of the breather re-route or just because they think it looks cool. To me, it's unnecessary and if not managed/maintained, creates a significantly worse problem than the original symptom it was hoped to address. If you decide to use one, just keep an eye on it and clean or replace it once in a while. Maybe every 2,500 miles. The filters I've seen don't specify the ability to be washed and cleaned, but I think you could probably soak them in a bucket of hot soapy dish detergent water, rinse thoroughly and sit someplace warm for a day or two to dry out before re-installing.

    Matteson is still correct in that the crankcase pressure has to vent somewhere, so if you don't run a filter, then the only practical option (and is what I do) is to just run your tube down through your frame and allow it to vent/drain to the atmosphere. Simple, provides free-flow venting, and requires no maintenance.

    One last thing on the topic- No matter what kind of re-route installation you go with, ALWAYS make sure your tubing is routed so that it continually travels downward so that all condensation is forced to collect at the lowest point at the end of the tube. No uphill curves along the way or you risk liquid collection and clogging where the tubing dips.

    Sorry for the long post.

  3. #13
    Senior Member lunaticfringe's Avatar
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    Sorry for the long post
    don't be sorry tork. that is an excellent post. thanks for spending the time to compose it.

  4. #14
    I'm amazed by the passionate input on this forum! Thanks again guys!

    I've read elsewhere someone suggesting using just two unadulterated tubes - one for each header - venting straight out and down. It sounds like maximum air flow to me. Is this a good idea - or are there reasons to stick with the tried and trusted t-section?

  5. #15
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    @Fastmart- Given the pressure coming out of the rocker breather valves is low, I don't think there's any value added for running separate hoses other than not having to buy a t-fitting. There's not a whole lot of room between the frame components for hose routing, so running a t-fitting to a single downtube would seem easier, IMO. Individual hoses can't hurt, but I don't think there's anything to be gained by it either.

  6. #16
    Many thanks Tork. Makes sense! - I'll do as you suggest! Parts now ordered.

  7. #17
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    Fastmart I have had great results in this rpm range, 2K to 3K with adding an extra ground wire to the top of the engine directly to the battery. This was after I had done the breather reroute. Also highly recommend the ECM relocate if not already mentioned above. These 2 mods are on this site and relatively easy to do. The ECM relocate is easy, but just took longer than I expected for something so simple.

  8. #18
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    On the breather mod, I ran 2 separate fuel lines, one for each cylinder down the left side of the motor, behind the oil cooler. Then behind the chin fairing and on the exhaust pipe. I do not see anything at the end of these hoses except some steam like condensation in the winter. Less parts is better in my opinion, I was going to tee both cylinders into one, but seemed like added hardware and labor was not needed. I want to spend as much time riding my Uly as possible, so anything that keeps me out of the saddle I eliminate.

  9. #19
    Many thanks Tbone! I ordered a battery cable today to do your mod at the same time - so I appreciate your encouragement that it's worth doing. I'll look into the ecm reposition in due course as I work my way through other possible issues.

    I have to say, I've had my my Buell a month. I bought it running rough on trust that it could be sorted - and have yet to enjoy it at it's best, so trying not to lose heart as I rule out one potential issue after another with little improvement... I trust it's worth it in the end?!!!

  10. #20
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    I think the mod has you build one, a ground cable that is? There are some Pics for that Mod.
    The ECM relocate maybe important as it prevents the connector(s) on the ECM from cracking, really hard to see the crack where the body and the Socket meet. Can cause a lot of problems if this happens, as explained by others on the forum. I relocated mine as it came through the themal blanket, I did not check the connector as I just glued it and moved it and as long as it works I do not want to know? The PO was about 300lbs, and I am 200lbs, so I am sure it had some pressure on it.
    My opinion these things you are doing should be automatic, when I get my next Buell It will be what I check or do first. Breather Mod, ECM relocate if applicable, Ground wire, then if things are still rough running troubleshoot till it is fixed.



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