Hi , I have an ex USA 1973 DT250      Starts easy when cold and runs well . However when after a good run engine is stopped and tried to restart will not fire up on kickstart.   New plug ,points and condenser recently fitted. Using ethanol free fuel with 50-1 ratio.   Hope someone can help.  Possibly not related but fuel filter bowl is never full but I never seem to suffer from fuel starvation..     Aubs from Wales.

Hi there I have the same bike with the same issue do you have any answers on this issue please? 

Could be that it is on the rich side when hot.  Don't use the choke when starting hot.  Try holding the throttle 1/2 to fully open when starting hot.  If you pull the carb make sure the float setting and needle clip position are correct.

Do you have the insulator spacer between carb and engine? 

How much time is passing before trying to restart?

Aubs,

The 1973 was, in the US at least, the DT-3, and not a DT250; this could help when looking for rare replacement parts.
On starting, when cold, use the Choke, and DON'T TOUCH THE THROTTLE!  When warm, use no choke and about one-third of throttle travel and kick when the piston is at TDC.

Hammer

Hi MARKT     I assume you are refering to the valve plate .  Has been removed and checked. Time to restart after long run about 1 hour.

I'm talking about the insulator spacer between carb and engine.  Yamaha calls it an "intake manifold".

Should be an o-ring on end of carb, insulator, then gasket, then reed manifold. 

Without an insulator, carb will soak up excessive engine heat which can make it hard to start when hot.

 



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Hi MARKT,  THANKS FOR THE REPLY.   i WAS NOT AWARE OF THE PURPOSE OF SPACER. . i DO HAVE  SPACER AND "O" RING IS IN GOOD ORDER.