Please, if there is anyone who have had similar experiences / problems to assist me with advice regarding the possible solution of mine.
About two months ago, somewhere in mid-December last year, I drove a few short irregular tours through the city until one morning after a something hard starting (outside was below +10 C) the engine warmed up, choke turned off, and drove about 5 km. After 15-minutes pause I started again and after some 100m engine began losing power, slowing down, jerking, coughs, whatever ... so I was forced to stop on the parking lot.
The engine is not extinguished, but choked at even the smallest throttle turning. I extinguished it. Visually inspect if something happened to the machine, if somewhere something is leaking, check the fuses, contacts ...
3 months ago motorbike was on preventive maintenance. Mechanic puts new oil, filters, chain and sprockets, timing chain tighting, new springs in the Bendix, carbs cleaned ...
I waited to cool slightly, then try start again. It started from the first, but as soon as I added a little throttle, coughs and choking ocurred. After 20 minutes of trying to solve the problem, and the seventh time of starting, I pulled the choke on and, lo & behold, everything is OK. I went ahead to the city and drived some 15 km without any problems.
Well, it would be good if the problem gone, but ...
After three days I wanted to ride again. Engine starts fine, but to my great disappointment after the warm-up engine sounds like a tractor, or perhaps a small diesel engine in boat. The sound of machine is not purring as "purrr-purrr" but "dum-dum" like hydraulic presses and vibrate very hard. Nothing changes eve after a 10-minute of warming-up. And engine beat harder when I turn on the trottle.
Everytime I started the engine same thing hapened. With the choke, without the choke - engine sound terrible and has no power to run.
I took the video with my camera so you can hear how it sounds, and here is a link:
Outside temperature was +10 ° C, three to four degrees higher in room. By shooting this footage the engine was not started for about 10 days.
The second video I took a few minutes after the first, when the engine was already warmed up.
I turned on the engine with no choke, and immediately after starting I add some throttle (revs) and engine sounds cool, but after three or four seconds it starts to choke and again starts to sound like diesel engine. This video is much shorter. Here's the link:
I transported motorbike to mechanics. The man had plenty of ideas what could be a problem, but none has led to the solution.
Spark OK, pick-up replaced, tested with another CDI's (taken from the engine without a problem), replaced some resistors, installations checked, switches ...
I tried everything. Well, almost
So, if someone heard about or had problems like mine, I would be grateful to direct me to the solution of the problem.
Btw. engine is 10 years old and has passed 40,000 kilometers.
Oil level OK. Coolant level OK.