Hello,
I recently picked up a very clean '91 ZX100C with a Muzzy 4 into1 exhaust, 20K miles. While doing some routine maintainence, I discovered that the exhaust is extremely discolored where the pipes bolt to the cylinders. Is this normal? The previous owner told me that stock pipes could be put back on the bike without a jetting change. My questions are: What size are the stock jets, and what is recommended with the Muzzy exhaust. The bike runs pretty well, just a bit rough at low end. I plan to tear the carbs down and do some work, I just feel it could run a little smoother. Any insights would be greatly appreciated!

 

In the service manual for my ZX-11D, it shows the main jet sizes. When I get home i'll take a look. I am not sure if they are the same as the ZX-11C but its possible. I would grab a jet kit for that bike though. Its obvious that it was not rejetted when the exhaust was put on and is now running very lean, which is a problem.

 

Horse sh*t, jetting and tuning is always required to meet optimal performance when swapping out any exhaust. I have a 93 manual only it seems.