Suddenly hot starting very difficult and low stationairy rpm.

[SkooterG]

The battery turned out to be 8 years old, I don't think that is really old.

That is OLD. Batteries in my hot environment frequently last 3-4 years max.

If I had a dollar for every problem reported around here that came down to a bad/weak battery..........

 

[RossKean]

Hello, an update. I had the opportunity to investigate further. I used injection cleaner twice, after another tank this gave no improvement. Because the battery was still in the back of my mind, I looked at it specifically. The starting voltage was initially fluctuating around 11 volts. This was the 1st start. 2nd starting attempt already fluctuating 8 to 9 volts. That is not good. Then connected a heavy power supply in parallel, this gave improvement. The power supply can deliver 30 amps at most, not enough. But I did have an indication, because the voltage now remained around 10 / 11 volts. Power off resulted in fluctuating starting voltage of about 9 to 10 volts. For me this was the reason to install a new battery. New battery and the warm start is good again, problem solved. The battery turned out to be 8 years old, I don't think that is really old. The longest I have done with a battery is 13 years. Apparently a bad battery gives problems with a good ignition, causing the fuel mixture not to ignite properly and therefore to become too rich. Engine became flooded. A half-baked starter motor itself has also played in my mind, as described above. But that is a lot of work, and engine has just done 32000 Km longer rides and I wanted to take the fastest and simplest way first without a lot tinkering. So far the problem has been solved. (Sorry for my bad English).

A new battery is frequently the cause for a lot of problems related to starting and low-rpm operation. It is still worthwhile to check out the current draw during starting using a DC clamp-on ammeter over one of the battery leads. (You don't need to access the starter itself for this.) Sometimes a new battery's ability to supply additional current without severe voltage drop can temporarily mask the effects of a failing starter motor.
Given that your battery is eight years old, it seems likely to be the root cause, but I would not ignore other possible issues.

That is OLD. Batteries in my hot environment frequently last 3-4 years max.

While that may be "normal" in a hot climate, I have always done much better where I live. I never use a battery tender other than for an hour or two a couple of times during our typical four month winter layoff. While we get moderately hot weather in the summer, it does not approach what you see in Phoenix. On the two Gen II FJRs I have owned, I got 10 years and about 240,000 km (150,000 miles) out of the OEM battery in my '07 and 12 years and 160,000 km (100,000 miles) on the 2011 OEM Yuasa - I bought the '11 when it was already 7 years old but with only 36,000 miles.
Even here, that is better than most. Some luck, but I am very careful to avoid deep discharge or overcharging. I have never been convinced that the regular use of a battery maintainer does anything to extend a battery's lifetime. In fact, one that isn't properly regulated or one that isn't compensated for ambient temperature can do more harm than good.

 

[Klikoo]

Today I made the necessary kilometers. In between I also stopped and had warm starts. The FJR is working flawlessly again. I hope to do at least 8 years with this battery.