Re: What CC motor is this?
The 6 mm studs were the standard a few years back- not sure when the 66 motors began most shipping with 8 mm studs- We dabble in an inexact science here sometimes I think because distributors get quantities of stuff and may take years to sell- so some of it is older new stock than others.
I have a 66 with 6mm studs- bought spring '09 from bikeberry- I think the 8mm has been out a couple of years now- most retailers are more likely to be selling 8 mm 66 motors as time goes by.
Someone said up above there was no difference in NT carbs- NOT SO. The NT SPEED carb for 66 motors came alomg about two years back- both that and the original NT- designed first for 50 cc motors- are being sold around. The 66 carb now says " SPEED" on the carb body up near the throttle cable and has it's own shut off valve- some old style can be found with the valve as well, so look for the word "SPEED". They are shipping for about $25 while the older carbs are maybe 10 dollars cheaper . The carb pictured above looks like the older NT 50cc carb- I'd upgrde that.
I'm just getting ready to test a 66 speed carb on a 50 cc motor with a billet intake- should do well I suspect.