I recently was given a 1985 yamaha vmax 540 here's the problem it fires on almost every pull but will not actually run for more than 2 seconds. I have rebuilt fuel pumps and assured they are pumping I have also soaked and clean carbs all passage ways. Compression is at 135 per side. And I have a very nice looking bright blue spark. Again it fires won't do more plugs are getting wet and It doesn't seem to be any different if I prime cylinder or just pull on it. Any help greatl appreciated I am completely confused thank you