I have an 84 643. Very well cared for over the years. Last fall I rolled it over for the first time. Changed all filers, fluids etc before restarting. Once I got the air purged it ran fine for a few minutes. Repeated procedure and each time it runs fine for a short time. Sometimes as long as 10 mins full throttle. Then it starts to lose RPMs and quits. Changed the primer bulb and fuel lines. Haven't gone through fuel tank yet. Any suggestions as to what might else be going on?
