Is it possible that it may have to much oil . When checking oil level the dipstick does not get screwed back in while checking but screwed back in when finished oil level check is right.
I thought it was worth a mention just in case it was over-filled and it could save having to pull it apart.
I also take the hose off the aircleaner when I've had this problem so I don't have to keep cleaning the carby of oil and to monitor the amount oil spitting out till it stops and then reconnect the hose to airfilter once the problem stops but I don't know if this is recommended by others.
