fazer 600 1998 running problems

[Dead Eye]

Sounds to me like an air / fuel mixture problem? Or maybe even an intermittent cylinder?

First couple of things to check is the air filter and spark plugs. Go for a bit of a ride, come back and leave the bike running for a few mins. Then remove the spark plugs (be careful, the engine will be hot) and check if they are clean or sooty. This will tell you if the bike is overfuelling.

Whilst the engine is hot, use a bit of water and squirt it on each of the downpipes. Obviously dont touch because again they are very hot - if the water doesnt sizzle then one of the cylinders isnt firing properly.

Do you have any idea roughly what sort of MPG you get?

This is just a couple of basic bits and pieces ive picked up, no doubt someone will be along shortly with other ideas

Also, if its running rough at low revs it could just need the carbs balanced. Do those quick checks first as they arent going to cost you anything apart from a bit of fuel