Hey there Pinion, what's weird is that your manual shows it as being a 1975 model, but looking around the Sportster site it shows that the "H" designates '70 through '79 and 5 as the year. So your manual and other sources are right. '80 was the last year to use a letter code which was "J", and '81 on up used a different serial number system.

 

I as well have just bought a iron head to move up from a 71 triumph now my iron head 1975 is killing me it has a carb that is not the one from the manual and its been in the shop two months and 3,000$ latter it brakes down one block from my house . the bike ran grate for two days and nothing but fire coming out the carb and pippes the second shop I whent to sold me new jets for the makunie harley davidson carb the jets were 175 now I have 160 . Im going out of my mynd and dont know wair to turne Im broke now and have no ride any one have any ideas on a carb and the right jets ect.. to get me up ? please

 

piercedreality......
If I could offer you a suggestion here, it seems like you have searched under 1975 ironhead and found this thread (which is fairly old) and related to another problem a member had posted before.
My suggestion is to start a brand new thread regarding the problem(s) you are having and this should result in a better response, and hopefully some answers to your question(s)........pg