Engine Surging/Hunting 2-3 rpm (again)

[fastmart]

Hi guys, I've read through the forum and seen this issue has had lots of coverage already.
I'm a Buell newbie (and trying to keep heart with such a potentially awesome machine) - and not much of a mechanic either.

The issue: engine surges/hunts especially at 2-3,000 rpm at small or steady throttle openings (much smoother when opened wide/accelerating hard or above 3,000 rpm) - so makes slow town riding or steady traffic around 20-35mph uncomfortable and takes the shine off such an awesome machine.

My new beast is a xb12x 2008 with Thunderstorm engine, stock exhaust (for now) and 9,000 miles.

Just had it given a full service by a backstreet indie Buell mechanic, so new plugs, HT leads, engine + transmission oil + filter in the service, but didn't have software for ecm or tps checks. Improved the condition a lot, but not completely.

From the forum, I see there are a number of possible issues/cures still to explore:

1.TPS reset
2. ECM remap
3. Tighten grounding wires
4. Breather Mod
5. Possible oil in the breather element (from over filled oil)
6. Exhaust valve malfunction
7. Any other suggestions???

Are any of these easy/best to try first as a newbie and unsure mechanic? - Or should I just keep throwing my hard earned cash at the backstreet guy or pay top whack for a Buell friendly HD dealer, bearing in mind the cost of working through all those issues...

Also, should I sort this issue before upgrading exhaust, or is the excuse of a new exhaust also a possible cure?

 

[wolfo68]

1 - probably not going to be your answer
2 - shouldn't need it since you have the stock exhaust
3 - should always make sure they are tight
4 - try it, people have had good and bad experiences
5 - maybe
6 - zip tie the wire so it stays open, it won't hurt your ride but it will give you a better idea of what's going on
7 - try those first, maybe dirty injectors? Maybe even a slow intake leak under pressure.

Don't try throwing new parts at it while you already have a problem, you'll just confuse yourself and those that are trying to help you.

 

[fastmart]

Really helpful. Thank you! - I can certainly track down the ground points, then I'll see what I can figure myself and take it from there.

 

[user_deleted]

fastmart: wolfo's info is always excellent. though my uly is a 2007 with different ecm and dfi system i found that the surging and hunting and pecking in the rmp range you mentioned was so incredibly annoying i was going to sell it. for me and my uly, again being a 2007...a breather re-route, NGK DCPR9EIX spark plugs, tps reset and replacing the stock map with a common racemap cured all the ills. it still does not heavy loads at 2000 rpm or so but then again no XB's do. if i were you i would try the plugs, the re-route and tps reset which is very easy on your 2008.

 

[fastmart]

Thanks lunaticfringe!

I've now tried zip ties to keep the exhaust valve open. It hasn't cured the problem - but I love the deeper sound and new engine characteristics. It seems to pull more strongly from 2k rpm - and even roll on (just) from around 1.5k rpm if I'm being really lazy around town.

The bile had a full service, so new plugs and air-filetr were put in - and certainly reduced but not cured symptoms.

I've check ground wires. All tight - but think I'll take them apart, abrade and file back frame paint to ensure good contacts. I also noticed the left hand ground wire (by fuse box) touches the aluminium chassis for the battery. I don't know if that would have an effect - but I'll adjust it to not touch anyway.

Then I'll continue to work through the list. I'm trying to find the clearest write up for the breather re-route... anyone got any suggestions?

 

[fastmart]

Having removed the battery I've noticed that the bracket I was concerned about is actually bolted into the earthing point - so I guess it makes no difference.

 

[user_deleted]

Thanks lunaticfringe!

my pleasure sir.
regarding the breather re-route here's what i do....and there are variations but i do NOT run any type of filter or "catch can" at terminal end of your new breather hose. an inexpensive filter is fine but not required.
1. remove air box cover, box lid, filter element, 4 torx screws for base plate, and with flat blade screw driver push the 2 breather tubes down thru their respective holes in airbox base plate. now as you gently push rubber air horn thru air box base pull up base and set aside. that will expose the air horn, top of motor, and your 2 breather hoses....one from each head rocker box.
get 3 ft length of 3/8th ID quality rubber hose normally used for oil line plumbing. you will also need one 3/8th T fitting. available at any auto parts store. trim the stock hoses from each cyl. head so that they will gently curve and attach to the T fitting and T fitting lies on top of motor just to left of airhorn assembly. then route your new 3/8th hose from end of T fitting down over top of rear of motor, out thru frame cavity at top of rear shock top mount and down to right side towards top of swingarm. terminate that hose there. plumb it neatly and use ample wire ties. when done double check that your breather fittings are securely pressed into their respective head grommets. they must be tight and secure. hope that helps.

 

[user_deleted]

forgot to mention.....you should find and use suitable rubber or plastic plug to seal the 2 remaining holes you will now have in the airbox base that formerly held the breather tubes. i glue them in from the bottom.

 

[fastmart]

Thanks lunaticfringe... may take me a little while to get organised for this one but sounds like a must!

I've checked and cleaned/abraded all my ground wires - with no difference.

Will try TPS as soon as the engine's cold again (as you say - easy to try so worth ruling out).

 

[Matteson]

You NEED a filter on the there dude. Pressure is being built up and must release somehow. It's called a "breather" for a reason. When I had mine on the xb I could feel the filter and it was so it could still breathe and below it was a small length of tube that caught the liquids. Research pcv valves and engine crankcase blowby.

 

[user_deleted]

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.

 

[Tork]

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.

 

[user_deleted]

Sorry for the long post

don't be sorry tork. that is an excellent post. thanks for spending the time to compose it.

 

[fastmart]

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?

 

[Tork]

@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.

 

[fastmart]

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

 

[Tbone]

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.

 

[Tbone]

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.

 

[fastmart]

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?!!!

 

[Tbone]

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.