I have a problem with my 1993 VN750 A9. It starts perfectly when cold but when the engine is really hot, say after a fuel stop, it can take a long time to start again. Battery & plugs are good & i've checked the throttle/choke cables & they are all adjusted correctly. If I wait 10-15 minutes it starts fine. Once running it goes perfectly. Any ideas? Also, I have aftermarket mufflers fitted, is there any way of reducing the backfiring I get on the over run? Had thought of backing out the pilot screws on carbs a little but am reluctant to do so until I have some advice on the matter. Have pulled the plugs after a good run & they seem normal in colour.