Common Technical Issues : FZ-1 / FZ-S10 (06-07)
BRAND : YAMAHA
MODEL : FZ-1 / FZ-S10 (06-07)
CATEGORY : Street Bikes
TECHNICAL ISSUE DETAILS
These Yamaha models have a permanent magnet battery charging system, consisting of a very small diameter stator with three output wires, which feed into a very large regulator/rectifier. This unit rectifies the AC into DC and regulates this DC to 14.5V to ensure proper battery charging.
The output from the regulator/rectifier connects to the battery through a main fuse. The alternator is mounted behind the cylinder block.
Common fault in this system: TEMPORARY SYSTEM OVER-VOLTAGE: THIS IS A DANGEROUS SITUATION WHERE THE REGULATOR/RECTIFIER CANNOT KEEP THE VOLTAGE LOW ENOUGH AS THE OUTPUT FROM THE STATOR IS VERY HIGH. THE DANGER LIES IN THE FACT THAT THE FUEL INJECTION SYSTEM SHUTS DOWN ON OVER-VOLTAGE WITHOUT WARNING!
We have seen this issue occur on machines that are ridden hard (like: on the track). The average rpm is very high, meaning the stator output is very high, so the regulator/rectifier sees a high load which raises its temperature. At a certain point the regulator cannot keep the voltage under control and the fuel injection then shuts down to protect itself. One simple solution for track bikes: disconnect one of the three stator output wires. This drops the stator dramatically but at high rpm there is still plenty of output to keep the fuel injection system going. (at typical track use rpm)
For bikes used on public roads the risk of this happening is fairly small as the average engine rpm is much lower. But it is something to look at when the bike is used hard.