1980 xl250s

[alfiec]

Hi, I recently bought a 1980 XL250S, 5600 miles from new and is in really good original condition, been garaged for years. I filled it up with unleaded on advice that it would run on it ok. However, it starts after a couple of kicks and will run fine for 1/2 a mile and then cuts out. Leave it for a minute and then she starts fine again! Runs for 1/2 a mile and cuts out! Tank is clean and carb looks ok. Any ideas?

Thanks

[Lumiya]

Sounds like the tank relief valve is clogged (normally in the cap or sometimes seperate depending on the bike)

But as petrol is removed from the tank a vacumn builds up and stops more petrol being removed, when you stop a little air gets back in so it starts all over again

[raymo]

as Kymmy suggest

check the simple stuff.. also run some carb cleaner through it.. best results are on tick over as this is when the fuel is flowing mainly through the pilot and hard to clean bits .. so leave the bike ticking over for 15 mins ( the recommedatons is an hour but this is fine for water cooled bikes , bit different if you have an aircooled lump and tetchy neiybours )

its fuel related so clean the fuel side and make sure that breathers etc dont have wasp nests or other debris that gets into wee crannies over the years when a bike is shed bound

[Pigford]

If a bike been standing for a few months, let alone years, the carbs will more than likely need a proper clean - as in "ultrasonic" coz the small passageways will block easily with the modern fuels