16 tooth sprocket for XTZ660
I have just fitted a 16 tooth CS sprocket to my 1999 XTZ660. I needed to grind a VERY small raised area of the crankcase to allow the sprocket to be fitted. Took all of 2 minutes to grind off and allowed CS sprocket to slip straight on. Needed to use a Dremel tool as it was pretty tight. It is a tight fit, but certainly not looking like causing a problem. The whole process took about 25 minutes from start to finish.
With the standard rear sprocket (45T) it gives a final ratio of 2.81 compared to a 15:43 of 2.86, and a standard 15:45 of 3.00. The bike cruises on 4100rpm at 100kph and 4500rpm at 110kph. Feels comfortable and not stressed at all. Cant report on fuel economy changes at this point, but will endeavour to post changes.
Just curious, did the 15:41 (2.73) "lug" the motor too much in top? What was your fuel economy compared to standard? - I have been getting about 17.5km/L on mainly long open stretches, and upto 21km/L on slower sections where going maybe 80kph in 5th. The main reason for the change was to reduce fuel consumption at cruising speeds, where I spend most of my time.