Engine numbers...again!

[bigdog]

Sorry to bring up the subject of engine numbers again. I know it's been covered elsewhere and I've read the threads but can't find an answer to my question, which is this...
My frame number is 4R5-017939, which translates into an XS400 Special 2. However the engine no. is
2V6-000573. Obviously the original engine has been replaced. What I want to know is what year is the engine?
According to the Haynes manual the original engine would have had electronic ignition, rather than points. But if this replacement engine is older then it will probably have points. So which is it?
Yes, I realise I could start taking bits off the engine to find out, but as I'm a lazy sod I thought I'd try the forum first before venturing into my cold garage.

 

[xschris]

4R5 is a 81-H special 2, 2V6 is a 79 2-f xs400. But that is for u.s. models. A 2V6 model would have points but if the bike is a TCI bike it may have been converted. Pop the points cover to see. Pics of the bike would also help.

 

[bigdog]

4R5 is a 81-H special 2, 2V6 is a 79 2-f xs400. But that is for u.s. models. A 2V6 model would have points but if the bike is a TCI bike it may have been converted. Pop the points cover to see. Pics of the bike would also help.

Had a look under the cover. No points in there, so it's obviously been converted. Thanks Chris