Just got my hands on a little 100cc yam no v5 but reg says 1983 problem i have is i dont know exact model number if any body can help 9 digit VIN is 

2U0 011344 reckon it is a yb100 yet similar 83 models have different speedo and cover for oil tank is different on google image searches any help appreciated

Hi Des, welcome to YOC. It is good as a new member to head over to new members section and say hi and introduce yourself etc.

This 9 digit vin does indicate that you are correct and it is a YB100. It does look like it has been chopped and changed a little so not surprising it looks different. Half the rear fender,brake light and indicators have gone also. (I can't actually see the meter/speedo in the pic, is it one with ignition on the right, speedo on the left and a 3 lights that say 'turn' 'oil' and 'neutral'? - I assume it is possible that it was registered in 1983 but is older model - maybe 80/81)

For reference I used this list to find the model number http://www.johnnystoybox.com/yamaha_parts_cross-reference.htm

Do you plan on doing some restoration?