Hello,New to this amazing site and this is my first post. I spent some time searching this site and reviewing the 1974 Yamaha DT 125 service manual that I downloaded. If my question is covered in an existing post please direct me to the location and excuse my lack of experience navigating the site. As the subject states I have a new to me 1974 Yamaha DT 125 that has the "autolube chain feature" as others have put it in different discussions. I have already put a lot of time in fixing various issues to get it back up and running as it was pretty rough to begin with. My questions are, do I have to remove the starter/generator assembly to get to the second case to find the leak? I have read that it could be coming from the primary sproket seal or the clutch shat seal but it does not appear to be coming from the shifter seal. Also, what are the recommended sources for the seals once I determine which seal is leaking? Any replies appreciate and thanks for the great resource. I am attempting to post a pic of it, and hope it will attach correctly. 

 

Buy your seals from Yamaha.

Thanks for the reply as I really appreciate the advice! I have found many parts online for this on but have not been able to locate any of the seals that might be leaking as a OEM Yamaha part. Could you please recommend a source to look for these seals?

Your local Yamaha dealer or an online Yamaha dealer such as RMATV-MC (my favorite) or Partzilla.

www.rockymountainatvmc.com/oem-parts/Yamaha

Greetings from Tennessee 
   Good looking bike

I've never worked on a DT125 so can't give you an definitive answer but a sure way to find out is to remove the first cover then you "should" be able to see if the generator has to be removed. Sorry I can't give you a better answer but I'm sure someone will come along that has actually worked on the DT125.

Generator only needs to be removed to change crank seal... not very likely crank seal is "oiling the chain".

If the oil is coming from the engine and not from say, the autolube tank/hose leaking, most likely the sprocket seal, clutch pushrod seal, or shift drum cover leaking/broken.

Thanks to everyone that replied to my post and I appreciate the insights that you have shared. It is nice to know that the starter generator assembly does not need to be removed as that looks like it might be beyond my capabilities to do correctly. I replaced the auto lube hose already and the tank did not appear to be leaking. After closer inspection I am assuming that it is the primary sprocket seal as it is running down the chain a few links before it drips to the floor. I will take pictures of the process and post them to the site once I get time to get to the project. Thanks again for such a great site. 

The seal behind the sprocket is an easy R&R, the hardest part is having to loosen the rear wheel so you can get the chain off the sprocket, then have to adjust the chain again, which isn't hard just a pain. Other than that you'll surprise yourself and feel good about having changed it yourself.

Thanks for the advice. I have replaced primary sprocket seals on other bikes but not like this DT. I couldn't even verify if the starter generator assembly had to be removed prior to removing the case that covers the front sprocket. Most bikes that I have worked on did not require removing a cover to get to the primary sprocket. Hope to get at this soon and provide an update.