danielvdeleito

30.000 miles on my bike and this happens to me when the battery start making older. After battery replacement the issue is gone. I monitor all my electrics and the generator is ok but the battery is 12.1 volts after turn on the key and let the fuel pump works (normal battery needs to show minimum +13 volts) My research conclude in: the crossplane crankshaft engines require a very optimum and fast rotation from the starter motor. Low or even non optimum voltage from the battery produce this issue. In cold days can be worse. Mike, let me know if the problem disappear if you decide change your battery.

Thats correct. Exactly as you say many Motorcycle companies recommend iridium SP, but this not depends of the manufacturer. Depends of the model. This is why Yamaha DO NOT recommend on the fj-09 even with a bigger stator. The stator send energy to the electric regulator and this to the coil (in modern engines is an electronic coil). The coil is preseted with an specific amount of power to each spark plug. The preset amount of electricity come from the energy consumption coefficient. If the spark plugs are running with a poor spark, you have a lack of power producing extra battery consuming and poor combustion in the chambers, which produce "rich mixture explosions" which produce excess heating. This kind of issues are not big deal in Standard engines, but in crossplane engines (like the FJ09) is other history.

Ok Guys. I want to try to explain my experience which I think is the conclusion for this post. I'm not professional mechanic but I have lot experience with mechanic and engineering. The science: The only difference between standard and iridium spark plugs is the material and size of the tip. Iridium spark plug: smaller tip size but better material = This better material prolongs the life of the spark plug and avoid corrosion and carbon, but have a cost: the smaller size require more "energy" from your stator/battery. In a car with a regular alternator is not a problem, but motorcycles using extra compact stators is a big deal. The history: Since I install iridium SP in my FJ-09, it takes more cycles from the starter to start. With standard SP take 1/2 to 1 cycle to start and with iridium take 20-30 cycles. Also, when the motorcycle is on idle, the engine have poor or missing explosions (this explain overheat exhaust temperature). After 3.000 miles my battery die due the power consumption and the over duty use on each start (I'm everyday rider, so I start my motorcycle 2 to 4 times per day). Also my fuel consumption increase a 20% more. The conclusion: This is the reason why neither Yamaha or NGK recommends Iridium SP to some motorcycles. Instead, according the shop manual, they recommend replace SP every 12.000 miles I hope this information helps everybody.