Problems Running In Rain (bogging down, surge in power at high RPM)

[Allaband]

Raining the past couple days in LA. This is my first experience with the Buell in rain. The engine idles low, around 6 or 7k rpm. When I accelerate it sputters and runs up slow. Stalls easily. Feels rough, kind of like running on one piston but I'm not sure how that feels with a V twin engine. If I wind it up to 5k rpm it will blow through the problem and run right, but when it drops back to idle is goes back into the problem. My commute is only 30 minutes so the engine is probably not properly warmed up. Anybody know what the problem is? Tomorrow will be sunny again so I'll know if it was only the rain causing it. I hate to think this bike will always run that bad in the rain. The power surge when the engine finally blows through the problem is troublesome. More then a few people today saw a blue Buell riding a wheelie through an intersection in the pouring rain.

Thanks for any help.

[LouWambsganss]

Moisture can exacerbate existing electrical problems, such as worn spark plug leads, chaffing power/ground main harness wires, bad sensor connectors, etc. It could also maybe throw off sensitive sensor outputs like IAT or TPS. Or it could be that everything is working normally and the rain is keeping the engine temp low, which causes the ECM to apply a correction based on ECT sensor input. If your fuel calibration is not correct, that could cause a problem. Having a way to access the ECM data (ECMDroid or ECM Spy) will help with all troubleshooting.

[user_deleted]

your lack of info precludes any accurate assessment of what's ailing your XB other than random "check this---might be that" responses. you provided nothing regarding year/mileage/model/history....nothing.
use the link below to manually check for any known stored fault codes. betting you have several.
if your airbox is modified check for a soaking wet air filter situation which causes identical problems to what you described.
also check the TB rubber intake horn to airbox base plate connection. it must be perfect. when it's improperly installed the fueling in wet conditions is horrible.

http://www.badweatherbikers.com/buel...77/146574.html

[ocgreenmachine]

What kind of airbox are you running? I used to ride 60 miles a day, 5 days a week in all weather. I had the open airbox mod (removed inner airbox, American Sportbike air filter cover) with Stock airbox cover (vent in front over the gas cap) and when i was riding in heavy rain the filter would get saturated with water and i would get rough rpms and what seemed like only one cylinder firing when throttle opened up. I changed airbox covers to a carbon fiber cover with the vents off to the side and it no longer occurred. If this problem only crops up with rain, I would explore this as a possible cause.

[Allaband]

Thanks for the help everyone. I went searching for airbox problems first. I am new to Buell and new to this bike so I can only assume things are stock. I seem to be running the stock (closed) airbox. It has a K&N filter which needs cleaning. The velocity stack has some cracks below the airbox and above the metal retaining band so I'm probably getting air in there. Below the retaining band the stack is crumbling so I obviously need a new one. Any suggestions on sources for a new velocity stack? The crank case breather hoses are also cracking and I'd like to replace them while I'm at it. What kind of hose should I use for that? The biggest problem I found was a port on the right side of the throttle body with a rubber hose. The hose ran down the left side of the bike and was plugged off. I think this is an evaporation emissions control device for California models that the previous owner removed. That hose was busted wide open so there was free-flowing atmospheric air straight into the throttle body below the throttle valve. I shortened the hose and re-plugged it. I also found some messed up wires behind the throttle body. Seems someone routed the wiring wrong and things were rubbing together. My manual doens't have a clear picture, if anyone can take a picture of the wiring behind the throttle body that would help me understand the proper routing. My bike is a 2005 XB9SX. I also found the foam seal where the two halves of the airbox press together is missing about 8 inches of foam. I'm sure that's not the issue but I'd like to set it straight. Anybody know where I can get that foam? I need to find good sources for Buell parts. I also need one of the bolts that holds down the airbox.

Thanks again for all your help!

[Cooter]

Buellmods.com or Buelltooth.com will have a free .pdf manual download for you that will include the pics you need the should be easier to see, and has wiring routing diagrams. Or 'Google images'.
The velocity stack and lip seal below it are critical to proper running (Like Lunatic said). SPHDonline.com is a great source for nos parts, otherwise theres a ton on e-bay. You are right about that emissions hose.

The bolts are just 1/4-20 pan-head shoulder bolts. If you want the 27 torx, they will cost you more.

An air-cooled engine warms up much faster than a water-cooled one. Don't rev it or ride it hard when it's just started, use good synthetic oil with a high shear strength additive and the right weight for your temp range (In Cali thats probably 20w-50 all year) Just a couple minutes to warm up is plenty (depending on ambient, of course).

[ocgreenmachine]

One thing you said... your bike idles between 6k-7k rpms... way too high for idle if I read that correctly. Idle is ideally around 1200 rpms. Mine is personally closer to 1100 for the loping harley feel. The sweet spot for power is between 4k-6k. I am also in southern california and run 20w-50 year round.

[Allaband]

Thanks again for the help! Those resources are great. I will be sure to warm up a couple minutes and use 20w-50. Any recommendations on oil brand?

I find lots of velocity stacks on ebay pretty cheap but I'm not sure what models share parts. My bike is a 2005 XB9SX. Do all XB bikes share the same velocity stack? How about the Ulysses? Or the Firebolt? The 2003-2004 velocity stack looks different. Is there an online parts microfiche I can use to cross reference this stuff?

I rode the bike to work today and it ran better with that plugged emissions hose. More smooth control especially at low speed.

Sorry, I made a mistake with the idle speed. In the rain the idle drops to 600 or 700, not 6 or 7k!

[ocgreenmachine]

I personally use Valvoline VR-1 20w-50 per recommendation by my mechanic buddy Jacob Stark, although Amsoil and Mobil1 are both great products as well. Especially if you regularly change your oil within 5,000 miles.

[user_deleted]

Any recommendations on oil brand?
any correct viscosity for your temp works fine in the motor. go with what OC said or do as i do and go cheap.
in the primary i've tried them all including ATF and to this day have found nothing shifts smoother than Amsoil 20-50 cycle oil.

Do all XB bikes share the same velocity stack?
yes. and the same spring clamp

1000-1050rpm on the warm curb speed idle.