Motorbike is a fuel injected single cylinder 2010 Honda XRay 300, 6 years old with 130,000km. The bike is touring and used daily.
Normally when the bike is hot and has been running for some time and cruising in 5th gear at 100km per hour and around 6000rpm, but also on slower roads at 80km and 5000rpm, there will be a sudden drop in power and deceleration. It feels as though the bike will stall but as you drop gears it responds with a lift in RPMs and somewhat stabilizes speed. This process can sometimes continue down to second and then I am forced to test each increase in gear to see if it is responding if not check back. This will continue for a few minutes until the bike returns to normal performance and I can cruise in fifth gear.
This problem has deteriorated over the past few days, the initial instance was brief and occurred once during a day of several hours of riding. The problem has however increased in frequency and severity where it was happening several times in an hour and now has reached a point where I am unable to cruise for more than a few minutes in 5th gear, 4th seems more stable and seems to have a better average speed given that once the performance drops in 5th it takes several minutes in lower gears at 40kmph until you can step up through the gears.
Does anyone have any idea what would cause this symptom?
I am hoping to have a logical interpretation so that I can aim to remedy it next time I reach a location where I can work on it.