My struggles once it reaches around 4000rpm

[Xb12r.joe]

I have a 2004 xb12r and i recently changed the spark due to the fact that the bike was occasionally struggling which would result in the engine light turning on.

After I have changed the spark plugs, the bike got a bit worse. The bike struggles more often, almost every time I ride now. I put NGK Iridium spark plugs.

Any suggestions?

I don't want to take it to a dealer since they charge $200 just to look for the problem...

 

[BambamXB12r]

Did you gap them?

 

[user_deleted]

a few things to consider here:
1-if done correctly changing plugs will improve overall performance...not worsen it. check your work for a disconnected sensor wire....faulty spark plug wire.... anything you might have disturbed under the airbox base plate area.
2-define "struggling". general rule of thumb with any bike is: when cruising or accelerating if the bike feels as though you are turning the kill switch on and off in extremely rapid succession it is ignition related. under identical conditions if the bike feels as though you suddenly hit a 100mph gust of wind it is fuel related.
3-before you do anything else follow the below. you most likely have 1 or more historical trouble codes. it or they are diagnosing what's wrong and stored in your ecm. retrieve them and proceed from there.

http://www.badweatherbikers.com/buell/messages/32777/64701.html

 

[rchuff]

do not need to gap the iridium plus and if you do be VERY careful of the tinny piece of metal at the end of plug . If you break it off they are junk then. I do not gap mine I use them right out of the box. check your plug wires see if in good shape and if on coil all the way some times they wiggle off coil. ^^^^^What John said to check the following .

 

[user_deleted]

I don't gap the spark plugs. I installed them right out the box which matched the ones that were in before.

And lunatic, it's almost like the 100 mile gust of wind you explained. It happens often, almost feeling like it lacks power but really doesn't.

How can I fix this??

the approach i would use is: recheck all areas you touched during plug installation for any disturbed wiring plugs....vacuum plug still attached to TB unit....ect. then using ecmspy run diagnostics on the bike and see what it reveals. if you suspect fuel delivery problem check the vent on your frame gas cap as well as frame vent fitting and line to be sure all perfect. you have close to a 12 year old bike and the pump might be headed towards death-row.