Bad starting after warm up

[WGuaire]

  Running a 1983 Vision with the factory fairing.

When I do the cold start, I leave the throttle closed and the choke on. Then, I hit the starter button for a series of short cranks. I assume that fuel is being pulled in then. Then the engine will start to burble and I leave the choke on. Warm up is a consistent process. The temp gauge goes up and we're ready to run.
  I used the Vision to pick up something from the grocery store and one other stop and go. Obviously, the engine was at running temperature. When I got back to the garage, I stopped the motor. Then I tried a restart. The Vision wouldn't start. Is there something I can do to get the Vision to restart after running?

[Walt_M.]

Could be several things. My '83 was consistently hard to start when warm until I discovered that it would start if I left it on the center stand. Never did find out why and eventually just changed out the carbs.

[jefferson]

I would first look into your starter. They are known for oil getting into them and then they don't work as well especially when hot. They draw more juice and can draw the voltage down to where the ecu won't fire.
The seal in the nose of the starter is the culprit and will need replaced with a newer double lipped seal with a tensioner spring around the lip. Clean all the oil out of the starter and shine up the brushes and commutator.
A good battery is a must as well as shiny clean connections on all the high amperage connections
The other thing that comes to mind is we have an accelerator pump on the carbs and you can flood the bike by twisting on the throttle. Once warm they don't need all that richness and will be hard to start.

[WGuaire]

Hi Jefferson - I'll have to check my service manual. I found this online.
  I'll have to check where the starter 'lives'!

https://www.cheapcycleparts.com/oemparts/a/yam/50042488f8700209bc787e73/starter-motor

I see the Haynes has a better section than the Yamaha service manual. I'll pull the starter motor and check it out.

[jefferson]

Be prepared to loose a good bit of oil as the starter sits below the oil level. The seal can be had from any bearing supply house. Just need the measurements with id and od the most important. the width can vary some.

[jefferson]

That link is for the starter clutch, not the starter. It is shown at the lower left, but only for reference.