Howdy everyone, I picked up a pretty rough RT1 a couple months ago for very cheap, I was told its a 1973 and from first glance it looked like one. However after getting it home I started looking at the VIN and checking with the VIN numbers from this site and I have been stumped since. Here is all the info I've got so far. The VIN on this bike is RT1-70639 which isn't in the VIN number range, and the case only says RT1. Last thing I tried to check was the carb numbers which are 275 E2 which points towards a 1970 RT1. Any help on figuring out what actual year this bike is would be appreciated!

A couple of photos would help .

Are you reading the frame decal or the numbers engraved (punched) in the frame I wish we could see some photos 

Nothing comes close in this link below. If it's piston port it's an RT1. If it has reed valve inlet its an RT2 or 3. Of course who knows if motor & parts have been swapped around over the years.
Just had a look at my DT1 as has an RT1 frame. RT1-113843, which is no help at all sorry.

yamaha-enduros.com/index.php/360-400-cc-vin-numbers

To me, the evidence is pointing towards a Japanese Domestic Market (JDM) import - quite a few were brought back to the US with returning service personnel.

1) 275 is the model code for the JDM RT1 for 1970.
2) JDM bikes had no individual engine numbers, just like yours.

If the headlight bucket is present, does it have a large red lens behind the high beam warning lens and/or a weird fuse/resistor type thing in the bucket (these are all in relation to a warning light that comes on if speed exceeds a certain level)?

Photo upload is not working at the moment. 

Thanks for the replies everyone! I just uploaded some photos of the bike to imgur so I can link them to this post. Here are some pictures of the bike when I got it home.   

As for the questions Ht1Kid, I was looking at the stamped numbers below the top triple clamp on the frame.

RT325, It is not a reed valve engine so I know the engine is at least from an RT1.

Gr8uncleal, I was wondering if the bike was JDM or not, due to the VIN not matching anything. As for the headlight bucket that is missing from the bike, it has seen better days and missing a couple things but it does run! I wish there was a way I could track down the other previous owners to ask questions, but I didn't receive any documentation with the bike.

However I do have what the seller called an "Aftermarket tank" that came with the bike, but it is actually a CZ plastic tank (that doesn't even fit an RT1!) 

Is it possible the number has been re-stamped--ground off & re-done. Na probably not. She's an early one with the steel slider forks exactly like my DT1. I'm sure you know--but RT1 prefix runs right through to "73 included. You did well to find an early one--enjoy, & thanks for the pics.

Thanks! I'm getting ready to pull the engine this evening and clean everything up. My plan is to get it running and ride the crap out of it. I learned last week when trying to start it why they call these bikes ankle breakers. I'll post some more pictures of it down the road after I get it all cleaned up and looking nice!

I would change the brake shoes before you go for a test ride they can and have become delaminated which isn’t pretty if you go flying over the handlebars 

Be a good idea to check the crank key for the flywheel because they're hard on keys unless the flywheel nut is very tight. One model had a retarding system for the points cam to stop it kicking back. Worked good too & i had that on mine. That system combined with the original decomp & it was very easy to start. If it was mine--i wish--i'd be on it & down the paddock to see how she runs & worry about making it look pretty at a later date. But then again i'm terribly impatient lol, more to my detriment sometimes. look forward to your results.