I'm working on making 2 AT2's into 1 good one.  The sprockets on both are mangled.  Both had 14 tooth front sprockets, one had a 44 tooth rear.

I'm looking at the shop manual and other 's saying the stock gearing was 15T front and 45T

Can someone verify for me what the stock gearing was? 

Most online places are showing only a 13T 't available.

Thanks!

My parts book , which is for the kickstart only AT2 , says 15 : 37 .
US electric start models may not share this combination .

Owner's and Service Manuals say 15-45 for US models, one of the old parts books I have says 44 rear.  

Yamaha specs are not always the most accurate and it's possible both are correct.

If you are keeping them 125's, going to a 14 front reportedly will actually give you a higher top speed as the 125's are a bit overgeared. 

Yamaha has front sprockets in stock in at least the 13 to 17 tooth range...  it's a super common sprocket so easy to get any size you want. Any good sprocket supplier will also have a good selection of front sprockets.  Same chain size and spline from 69-81 on the 125/175 Enduro.

Rear sprocket on the 125/175 has the same bolt pattern from 69-81.  The models up through about 1973 have a "step" machined into the inside of the rear sprocket to offset it in towards the wheel a little.  You'll need to make sure the rear sprocket has that relief or the chain won't be in line.  

Thanks gents. I'll be the first to say that I don't know much about 't wrap my head around a 14T front giving a higher speed then a 15T with the same rear sprocket gearing.
I'm good with just the standard gearing, this , will be for mostly road use. And I'm a big 'll just need to play with the gearing

appreciate the help!

The 125 doesn't have the power at lower RPM to pull 5th gear at higher speeds, especially on hills.  So you need to downshift.  When you get RPM back up to or near redline in 4th and need to shift back to 5th, the engine can't pull the higher gear so you end up bogging down and shifting back to 4th.  

Gearing down slightly on the sprockets raises the RPM a little and allows the engine to pull 5th gear better, so top speed is better.  

If you're a big guy and intend to ride at speeds around or over 50 mph, it would be a good idea to consider swapping to a 175 top end.  

Mark, would you recommend the 14/45 or 14/44 on an AT?

That makes sense to me.    I'll probably ended up going 14T front and 45T rear.

 

FYI Only: my 74 125 has a 45 tooth (factory) rear sprocket.