Engine shuts off while riding.

[LypareX]

My dads 88 vmax's engine stops while riding. He has to switch key off wait for 5min and it starts again until it happend again. First it happend after a warm engine, so i changed the 4 bobines (all cracked) the wires and spark plugs.
Also the battery was changed. I took it for a test drive of around 270km and it worked fine. When i came back home, my dad tried it up and down the street and said that there was not enough power than normal. (didnt knew how it rode, was my first time). He noticed that I putted the reserve on "ON" and he said that he had some issues in the past with that. He noticed that the bike would run better when put on reserve. but that wasnt the issue for now. That the bike kept on riding was the main thing for now. However the next day he went riding and after 95km it did it again and 2 more times even after a long cooldown. So even with a cold engine. The engine shuts off without warning, so no sputters or weird noises. I checked all the ground plugs and connectors but cant find anything.

I know this is alot to read but i am getting out of ideas.
Anybody has experienced this before?(btw i am new to this forum)

 

[marsmax85]

fuel filter, float levels and fuel pump first things I'd check .

 

[sdt354]

When it's in no start mode, spray some starting fluid or dump a little gas in the carbs. This will narrow it down a bit if she fires right up,or not.