Poor Fuel Consumption!!

[anglian001]

Hi, i have recently been on a trip to europe with my friend and have notice poor fuel consumption.
I was on my honda dominator 93' but i recently have fitted a low mileage FMX engine in her, but i still have the same carb which was off my old dominator engine which had done around 30,000 miles.
My friend was on his Yamaha xt600. When we came round to filling up i was paying 15 euros and my friend was only around 10!, i worked out the rough MPG and i was around 30 and my mate around 50! Surely something is wrong?
I have noticed poor mpg with the old engine so maybe a carb problem? i have stripped down and cleaned the carb and its as clean as a whistle! Do some parts get worn? Thanks for any help!

[zbzrzuzczez]

worn needle, worn jets, dragging brakes, faulty wheel bearings, oversize jets. these things come first to my head.
what does the spark plug says? it must be dark.

[Rubberchicken]

The needle jet tends to wear out over time, it turns oval and this makes your midrange where you spend most of your time rich. This bit:



The one on the right is ever so slightly oval. Replacing this together with a platinum spark plug gave me 6 extra mpg.

50ish mpg is about right, 30 is very much off though, that won't be just a problem with wear.

Have you checked things like the state of the air filter?