Most Vee owners would say that around 140 miles per tankful is around the norm, so something is amiss. If you can smell petrol, try and find out where the smell is coming from I.e. leaking under the tank or from the exhausts. If under the tank this would indicate a leak, so you'd need to take the tank off and check all the fuel pipes and joints for leaks including the underside of the tank where the pump fits. If the smell is coming from the exhausts this would be unburnt fuel. When was the bike last serviced and air filter, plugs changed, valve shims checked and all the throttle bodies and butterflies checked for correct operation and balance, there are two for each cylinder? Are both exhausts getting equally hot? If your bike has catalysts in the silencers (it should have) they have been known to block and if one is getting much hotter than the other this may point to this. Are there any error indications on the dash? I'm not sure what is likely to be seen on the early Vees.