Recently purchased a "1980" DT100. Bike needs some work, but the important bits (engine, transmission, and carb) seem to be in great shape. Thing is, as I dug into it, I noticed it has points, not a CDI system, as well as some other differences. I used some of the VIN charts here and the mystery deepened. 

Bike has a VIN of IT9-070801, which, at first glance, because of the IT9 prefix, means it's actually a 1977 DT100D. Thing is though, according to the USA VIN charts the VIN range for 1977 stops at IT9-017690. However, the 1958-2010 Yamaha Model Index shows the 1T9 VIN prefix being made from 1977-1983?
Also my bike is clearly red and not the yellow for that year.

I'm in Canada, but I thought we mostly got the same bikes as the USA. Did Yamaha just sell the 1977 DT100D for five years here with few changes? 

 from near Salisbury, UK.

Your VIN fits into the 1980 tables that you made reference to, so that sounds fine.

I guess that the models that the US and Canada got may have diverged at some point. Either that, or someone has replaced the cdi with points? A little more Canadian research needed here!   

The 1T9 model was sold in the US only one model year.  It's not unusual that other countries received a model with different specs from the US version.  

For example, here in the US the DT175 got leading axle forks in 1979.  The UK models stayed with the conventional forks the US models had in 1978 for several years.

Almost all the online parts manuals you find today are for US models.  

I agree with Alan, nothing strange here.  It's just not a US model so it doesn't match the US specs.  

Here's a link to a 1980 Canadian DT100 brochure. Colour is red and ignition is magneto (points). Sorted. 

YAMAHA DT100 1980 dealer brochure - French - Canada | eBay

 

Nice find Alan! 

Well, thanks Alan. I guess that explains it. For reasons I don't understand Yamaha decided the 1977 DT100D was just fine to sell for five more years in Canada with no improvements. This is a relief actually, because I thought I might have bought a mutant. I guess I'll start focusing on the 1977 manuals rather than the 1980's ones.

Excited to dig into this weird bike now. It seems like it's already going to be a lot less of a headache than my YDS3.

Smaller bikes tended to not get updated much.  The US DT100 probably only got the CDI because they needed it to pass US emissions or something.  

The GT1/GT80/DT80 in the US was sold for probably 10+ years with very little change except paint color and tuning to keep up with emissions laws.  

I actually wanted to dive into a CDI bike. Everything I own is so old it's all points. I guess at least I know I can fix it with a business card and a screwdriver