1996 GTS 5817 bog then stalls

[NScottW]

I have two 1996 GTS 5817. One runs fine; the other runs for about 15 minutes, bog down then stalls. If you let it sit for a few minutes it starts easily then will only run at low speed. If you try full throttle it will bog down again. Can someone suggest something?

 

[mikidymac]

Run with the seat off and see if you have any exhaust leaks.

As always a clean fuel system and carbs are necessary for proper operation.