hello everyone i think i found a good site here and am glad to sign up ... i ride vintage flat track a 1968 cl350. and live in vanouver canada and just bought a 1975 xl 250 it starts but wont rev out and it dies after 3 min of running.? if i keep kiken it over it will start for a short sec fiddling with the choke but then it dies and wont rev .it seems like a spark issue? any idieas