... when it runs at top speed for more than 30 sec it starts to stall and when I slow down it backfires. Sometimes it dies totally after that. Takes 1 min. to start it again.
- The plug was black. Replaced - but did not help
- I turned the pilot screw 1/2 clockwise to lean the mixture - did not help.
- Should I make the oposit? Make it richer?

Any suggestions?
Thank you!

 

Sorry! Not at top speed, but at high speed...

 

Choke stuck on?

 

This choke issue seems to be the most propable reason. I read some other posts and the symptoms are very similar: Idles fine and runs fine until I dont drive fast. Then it starts stalling and sometimes backfires.
How can I adjust the Starter (enricher) plunger, to close fully? Do I have to disassemble the carb? Or it is enough to adjust the cable play?

 

BTW, here you can see the Choke Lever Play on my bike. Whitin this range nothing happens:

(made by Photoshop )

 

I have already checekd the choke´s plunger and it was not stucked. How can I see if the string is wrong?
Any other idea? Thanks!

 

I took it to the dealer last week. The choke was not stacked; valve clearance o.k. In the carb there was a little dirt, so it was cleaned up. After that it ran perfectly. But only for 2 hours. This weekend it started backfiring and stalling again. Same symptoms as earlier.
Please, could anyone suggest something?

 

Even if nobody wrote suggestion, maybe some of you will be curious what was the cause of the above problem:
- There was some dirt in the gas and after cleaning the carb, some other dirts came from the tank and vents. I disassemblied the fuel vent and cleaned it, as there were lot of dirts. I filled gascleaner into the tank, so it has not stalled since that.
- The backfiring disappeared when I turned the Fuel Mixture screw out by 4 turns . I always thought I ran too rich, but the opposite was true, it was too lean although the manual says something like 3 turns only.
I hope 4 turns will not cause any problem...
I hope, I helped someone with this info.
Thank you