Would like some clarification about exhaust pipes on the XS400 series. The pic below is of the muffler on my son's '81 XS400. The muffler on my '80 XS400 does not have the four holes in the end. I have seen pics that look the same as that of my son's as well as ones that look like mine. Was one optional or were these holes drilled after the bike was bought to make the exhaust freer flowing? They look to perfect to be done later, though. Would the carb jetting then be different on bikes w/holes in the muffler end? Thanks!!

Would like some clarification about exhaust pipes on the XS400 series. The pic below is of the muffler on my son's '81 XS400. The muffler on my '80 XS400 does not have the four holes in the end. I have seen pics that look the same as that of my son's as well as ones that look like mine. Was one optional or were these holes drilled after the bike was bought to make the exhaust freer flowing? They look to perfect to be done later, though. Would the carb jetting then be different on bikes w/holes in the muffler end? Thanks!!

no clue but i like the look.

to me the holes don't look like they are perfect from center.. but could just be the angle.

I have no idea what they're for, but my '78 XS400E has them; my buddy's '82 XS400 Seca doesn't. So they're probably stock.

Thanks guys. The pic makes the holes look slightly out of alignment but when you view them in person, they are perfectly aligned. My son's XS400 is definitely louder than mine. He likes his sound (young guy) and I like my softer sound (old guy). LOL

Yep- that's funny, I was actually just about to ask somebody about that. My bike, with the five holes, is much louder than my friend's, with the single hole. Interesting to know.

What I'd like to know is whether or not the 5 hole muffler was standard in 1981 or if it was retrofitted to my son's bike and if the change required an increase in jet size? His bike has a hesitation that we haven't gotten into yet.