Question about performance exaust

[ssterry]

When I bought my 1992 Seca II it had a Yoshimura Exhaust installed. Iv been having problems off and on with carburetion and a friend told me when a performance pipe is installed the carburators need to be rejeted. Dose anyone know anymore information about this or if it is true. Also how would i find out if the previous owners have rejeted the carbs??? Any insights or suggestions on rejeting this bike??

[Jerry]

Rejetting is a constant topic of discussion. To look at past posts, take a loot at the Search tap at the top of your screen, and use it. There is also a good guideline for rejetting in the Tech Tips section of this site. Although it deals with the XS/XJ 1100 series engines, not your Seca II, it may give you some insight on how many sizes you may need to move from stock.

Typically rejetting is necessary with a performance exhaust. If you "read the plugs" you should be able to tell if you need to fool with yours; sooty black and you are running rich, tan means you are good, white means you are running to lean. Best way to check is to run at speed for a few miles, then kill the engine with the kill switch, coast over to the side of the road, and pull the plugs to check their color.

There is no way, short of pulling the carbs and checking to see what size jets are installed, to know if the previous owner (often refered to as the PO) rejetted the carbs.

Other carb maintenance should include setting the float height, cleaning everything (there are some very small passages in carbs!) checking to see if needles and seats are good, and getting the carbs synchonized. Check the past posts; these topics have been covered many times over and may give you some helpful tips.

Sometimes other problems, like bad exhaust manifold gaskets or leaking intake boots, can look like carb problems but are not. Even ignition problems, like a bad spark plug cap or intermittent coil, can have an effect. To really sort out your bike you will need to go through each system. Bikes these old usually need carb work, but make sure you cover the basics - cleaning, adjusting, synchonizing - before you start playing with jetting.