haha! good to know. Its not that i don't believe he ran a 17tooth, just trying to verify its possible on mine. I was referencing Partszilla and dennis kirk which both list a 15 tooth as being OEM with a yamaha part number and dont list any 17 tooth as being available, only 13-16 tooth. Amazon shows china 17 tooth units that "fit" a CT but when i looked at mine the chain looked very close to everything around it with the 16tooth that is on it currently. 

Thank you so much Mark for your kind words. Yes my CT3 ran very well! Unfortunately, my riding days are over due to my aging body (I am now 79 looking at 80 in a few months) and to be very honest, I REALLY MISS THOSE WONDERFUL YEARS OF THRILLS .  However, I have been working on Yamaha’s and enjoy doing so . A few months ago I sold my beloved CT3 to forum member RickC for a favorable price along with my old 1965 Honda 305 Superhawk. I feel very good knowing my bikes went to a very, very good home.

Like Dogboy said I would have checked the sprockets to see if they were stock. As for my DT125 it does need to be in the band but it will ride in 6th but does loose power in wind and on hills but that said it belts along. That's one of the reasons I like the heaver xl250 as it's way easier to ride on pavement (and has a much better seat) , but once off road these old 2T are insane fun!