A quick shot of starting fluid down the carb throat always gets mine going after a winter layup.
"When your mouth is yapping your arms stop flapping, get to work" - a quote from my father R.I.P..
always start with the simple, it may end up costing you little to nothing
Starting fluid and WOT. Also an uncovered R50 after a good downpoor can get water in the gas tank. Normally presents with a good idle but bogging on acceleration