I have a 2004 f4i and i just got an exhaust used but in good condition.
the question is on my stock exhaust there is a small hose attached to it and on the new exhaust there is no place for the small hose to attach.. what is the hose?, what does it do? and can i leave it unattached?

thanks for the advice

 

i don't think it's a hose, it's your O2 sensor....no you can't leave it unattached...you have to either get an 02 simulator or weld a bung on the pipe to put the sensor on. i'd do the latter because while running without an O2 won't kill the bike, it will kill your gas mileage....performance wise no difference...but BIG difference in MPG.

 

ok thanks! is it going to cost a fortune to weld it?????

 

not really...just get a bolt the same thread size and pitch as the O2 sensor, drill a hole about the same size in the exhaust, and have someone tac-weld it on. shouldn't cost much at all!

i think any shop that does exhaust would be willing to tack it on for you for nothing! takes like 15 seconds max!