Alright so as the title suggests I need help finding a rear sprocket for a new project. I thought it was a 1976 dt 400 but after checking the vin list it seems to be a 1975 dt 400. The engine vin is 501-015190 which after looking at the vin number list on this forum places it at a 1975 dt400b. Now the frame vin is 450-208639 which puts it at a 1975 dt250B. So my question is how do I know what rear sprocket I need? Both of the sprockets I purchased so far have been listed as fitting both a 1975 dt400 and 1976dt400. Yamaha parts house has both the 250 and the 400 as the same part numbers so I'm not sure what I need to do here but if I buy a third rear sprocket that doesn't fit I'm going to set the bike on fire and kick it over so my knee snaps in half.

Thank you for any insight I seriously appreciate it. This is my third Yamaha endure and I really love the hobby of fixing these guys but holy shit this is frustrating.

Obviously you have a "bitsa"... a bike assembled from "bitsa" different bikes.

It would be helpful if you posted pictures of your current sprocket/wheel, details and pictures of the wrong parts you bought, etc.

You might have a wheel from a completely different bike or the parts you've bought are listed incorrectly and not correct for a 75/76 DT250/400.

Cast into the the inside of the hub and sprocket carrier might be a number/reference and this should point us towards what rear wheel you have. As Mark said, pictures would also help.

 My only advice is not to do what I did. I found the OEM front but couldn't find the rear. So I just double checked the teeth count on here and ordered a part that 'fit'. What I failed to consider was how it looked so now I have an obviously new aftermarket rear sprocket that looks out of place on the bike. I might eventually end up replacing it again once I find the right NOS or at least one with a closer looks match.