2008 XB12Scg Sluggish, Doggy

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jriffe108

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Sep 11, 2011
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Hey Ya'll, I have a recently acquired 2008 Buell XB12Scg with approx 6000 miles. Bike was completely stock when I acquired it with approximately 4000 miles a few months ago. Bike had been dropped on right side in a parking lot when PO stated he dismounted while bike was in first gear on kickstand and bike lunged after releasing clutch lever. Only damage was dented/scratched front cylinder header and frame pad.

Bike ran good upon purchase with no problems but seemed to be low on power, torque. I changed engine oil and primary as soon as i got it home because it was low on primary oil, the chain was loose, and the engine oil was very dirty and low as well. PO obviously did not perform scheduled maintenance. Mobil 1 Vtwin was used to refill both with a Mobil 1 filter. I changed Brake fluid in both front and rear.
I started having problems with CEL which was traced to muffler servo actuator. I dissassembled unit and problem subsided for a short time but returned because the cam sprocket inside the servo slips off the motor drive sprocket. I disconnect the cable from the muffler and the bike ran better this way anyways.
Soon after, my bike developed an oil leak which I traced to the rear cylinder rocker box cover gasket. I rotated the engine and replaced both inner and outer rocker cover gaskets on both cylinders with revised harley gasket. I replaced both spark plugs with NGK Iridium DCP9IEX and performed a breather re-route with catch can. I cleaned throttle body with Teflon safe intake cleaner and removed all oil from air intake assembly.
I removed Mickey Mouse mirrors and added bar end mirrors. I removed and cleaned oil off fan assembly and reinstalled. Checked torque on all bolts and adjusted primary chain again along with clutch. I reassembled engine into bike and went for ride with no problems, but still lacking low end torque and power.
I obtained a Buell Race muffler and installed. Went for ride and the thing was a beast. Tons of low end torque, great upper rpm power, smooth idle, smooth cruising low rpm, Perfect. I rode about 50 miles that day.
Next day, ran great as well, only rode about 20 miles.
Third day, installed a K&N filter and TPS reset, bike back to running like ****. Jumpy idle, low power, etc. I performed another TPS, let bike idle for 5 mins until it was somewhat smooth, went for learn in ride. Still crap.
Ordered EBR Race ECM, installed, TPS reset, idle ten minutes, ride smooth to allow learning period. Crap, sometimes it has some good grunt, sometimes it stumbles. Lots of backfiring on decel, very loud and constant popping, whether its engine braking from 5000 rpm or 2500 rpms.
I was getting an intermittent CEL while riding, sometimes it would come on steady for 5 mins other times it was there for less than a minute, but always a steady light. High RPM runs, while steady cruising 75-90 mph over rolling hills the power was good, the engine sounded healthy. But low end grunt just wasn't there, at least 90% of the time. A few times I rip it open in first and would either smoke the back tire or raise the front wheel, but only 10% of the time. I rode a full tank of fuel, approximately 130 miles at all different speeds and gears with no major changes.
I just want my bike to run the way it did when i first changed to race muffler as it was a beast.
Checking codes revealed a 21,26,34. Clutch switch is currently bypassed with a fuse, Neutral switch appears to malfunction when engine is warm, operating temp, I removed exhaust actuator servo when race ecm installed, I removed IAT temp sensor and cleaned, tested, which appeared to be okay. I alos removed and cleaned IAT servo which had a bit of oil from when the breathers were still feeding intake. I tested this unit which also appears to function fine.
The only thing I can guess is the spark plugs may be fouled. I was trying to test everything else prior to removing plugs. I haven't ridden it since cleaning the IAT servo but don't believe it would make much difference at anything other than idle as it appears to be bypassed when butterfly is opened. Factory plugs were very black with dry carbon which indicated rich running condition when i swapped the NGK's. That was with factory muffler, air filter, ecm, etc.
I'm going to take her out for another 50 miles or so to see how she handles a fresh TPS reset, Clean IAT temp sensor and servo. Will pull plugs when i return to see what she's doing.
 
Change the plugs very cheap an easy.my bike 1000 to 2500 rpm very rough 2600 to 6000 smooth changed plugs smoothed everything out and got all power back
 
Okay, so, i've swapped back to stock ECM which appears to run better. As in smoother, less backfire on decel, less hiccups and more stable idle. Power feels the same everywhere except upper rpm range, 5500 plus.

I also prefer the fan logic on stock OEM vs race. Just sucks that I had to reinstall exhaust servo, may order an emulator.

Rode 50 miles with race ECM , tps reset and iac learn, with 10 miles worth of learning period prior to good times run. Then returned home, reinstalled stock, same as above.

I pulled plugs which had carbon along the edges, but the electrode and ground appeared to be clean, not white, but clean with no carbon deposits. Gap is approx 0.0035, which is what they came as when new. No rust or other apparent problems, these plugs have approximately 1000 miles on them.

It appears bike is still running rich front and rear. Both plugs were identical in color and gap. This is with race muffler and k&n with a few extra holes in airbox lid. I did not get a chance to run the bike after cleaning plugs due to rain. Supposed to rain all day tomorrow as well. I will make a few runs with bike when the weather clears and see if plugs change anything. It looks like I may be returning the ebr race ECM as the stock unit provides enough fuel to compensate for the race muffler and k&n.

I will order a cable to get a good read of afv and parameters. Will let you know how she runs with clean plugs.

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Anybody got a reccomendation on best place to pick up an ECM cable? eBay? A particular seller?
 
Octo, thanks for the info on the cable.

Took a good ride today with cleaned plugs, ran good, but still not where it was. Not really sure what is going on, I picked up a new neutral switch from HD, $16.00.

I guess a look at the ecm parameters is needed. and soon after, a custom tune.
 
I will definitely have to do that as I'm not familiar with ECM tuning. Give me a 4 barrel holley and points ignition with vacuum advance, i'll have her singing right along, lol.
 
Let's trade, then. Carbs are a complete mystery to me. I have a set of dual sidedraft Mikuni 44PHH's to throw on my 510, and I'm at a complete loss on where to start!
 

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