by Adam_Winstone » Tue Aug 30, 2022 2:04 am
As above, if it was running fine before adding new fuel, suspect the fuel!
A pal of mine had exactly this scenario and discounted my suggestion of fuel as he couldn't imagine that the fresh fuel from local petrol station could be a problem.
Anyway, he stripped the motor down, rebuilt with new seals... same issue. Asked a dealer, spent several hundreds of pounds in new crank, maghousing, fly side bearing, seal ang gaskets... same issue!
As a last resort he hired a van and called in a favour for me to look at it. I asked him to run me through events, step by step, which lead me to drain tank and float bowl, put in some fuel from one of my bikes.. problem solved, immediately.
You should never assume that fuel from a petrol station is good or uncontaminated. He learned an expensive lesson.