The Hebrew language has no letter "J", so at the very least the spelling is wrong. Of course, that doesn't stop the common spelling of Jerusalem rather than Yerushaliym.
The original 1611 Authorized Version was printed entirely without the letter "J". The 1769 revision of the KJV is what almost every KJV user has did insert the letter "J" as well as reversing the use of the characters "v" and "u" and other spelling changes. So in the case of this verse the spelling of The Name starts with an "I" in the 1611 printing. This is closer to the Yod of the Hebrew which is normally transliterated as "Y". Of course Germanic languages still pronounce the "J" as a "Y" sound. (Carl Jung is pronounced as "Carl Yung" for example.)
Judaism teaches that The Name is far too holy ("hallowed" even) to be pronounced. So when encountering the 4 Letter Name we substitute another word. In mundane usage we say "HaShem" instead, which is Hebrew for "The Name". It is believed that 2000 years ago, while the Temple still stood The Name was actually pronounced by the High Priest once a year on Yom Kippur.
The 4 Letter Name was vowel pointed by the Masorites which renders a similar pronounciation (with a "Y" at the beginning) to the KJV usage above. But the Masorites used the vowel points from the word Ado-nai and inserted them into the 4 Letter Name. So that pronounciation is known to be incorrect. On the other hand, some have claimed that the Masorites did vowel point correctly and then put out the story that they used the wrong vowels to keep people from attempting to pronounce The Name.
Others have used the verse "If My people who are called by My Name...." to prove another pronounciation. "Yehudah" (Judah in the KJV) is spelled with the 4 Letter Name with a Daleth ("D") inserted as the 2nd to the last letter. Therefore the claim is made that The Name would be pronounced the same as Yehudah minus the "D" sound.
But this is all speculation and because of the command "Thou shalt not take The Name of the L-RD thy G-d in vain" attempts at pronouncing The Name are frowned upon. (To put it mildly.) The tradition when printing Scripture has been to show where The Name is either by printing "HaShem" in the English translation, (this is the method Artscroll uses), or by printing L-RD in all uppercase (this is the method used by the KJV and many others).
So, treat The Name with reverence if you really feel that you must say it. Realize that if you reveal The Name to the unbeliever they will just turn around and then use The Name to curse you with or to make profane jokes. This would bring them under a worse judgement than they are already under. And this is one of the many reasons given as to why The Name is no longer pronounced.