FZRSupport: the FZROnline Archive

Hi all!

Im new to this forum and Im new to the FZR! I just purchased my fzr250 2kr a week ago and Im planning a few modifications. In regards to the exhaust could anyone help me with a query?
I have been told that the EXUP on the exhaust changes backflow so essentially the same as changing to the optimal exhaust to match the RPM BUT I have also been told it has nothing to do with back flow??

What I would like to know is if I can remove the muffler can all together leaving some piping and leaving the EXUP valve, will doing so have any effect on backflow? My theory is that the EXUP should take care of any backflow independent of the muffler.

The idea is that the variable throat that is an operating EXUP valve will maintain sufficient exhaust gas velocity under all conditions to stave off uncontrolled exhaust gas recirculation and the contamination of the fresh intake charge that goes along with it. That said, removing the muffler and its attendant restriction is an entirely different matter. You will drastically affect the jetting throughout the rev range, and you will annoy the hell out of your neighbours to the point where people will pour oil on your favourite corners.

Don't do it. The 250s are great little machines, and there are probably ways of getting more hamsters at the rear wheel, but ditching the muffler entirely really isn't one of them.

I wouldnt have thought the 250 would be loud enough to give concern without the end can. Theres a couple of folk who have been around my site and ridden thous without end cans & without issues.

Looking at it from an alternative aspect...Even the 1000 aint half as loud as a Hardley with slash cut pipes

Just my

Thanks for the replies guys! Iv come across a second hand Carbon muffler ill try out