3AJ top end with a 1VJ bottom end?

[Patrick]

G'day blokes.

I've got an 88 Xt600Z with a 3AJ engine, been sitting untouched for a while but lately, I've begun work on a rebuild.
Most of the way through pulling down the engine for inspection etc, and just as I've gone to split the case I've noticed that the flywheel side case is stamped "1VJ" which seems odd to me as I was under the impression that the 1VJ engines were from a previous model Tenere.
The cylinder head is clearly marked 3AJ, the compliance plate states it as an 88 model and the frame number, while hard to make out starts with "3DE" which I thought was exclusive to the 3AJ series. (Could be wrong, I'm new to Teneres and Yamahas in general) The final giveaway is that the instructions for splitting the case in the 3AJ workshop manual I have show things just a little differently to what I have on my bench.

So I'm assuming that at some point in time, the bottom end has been replaced and the 3AJ and 1VJ are compatible. Was this common?
What I'm hoping for is for someone more experienced to confirm this for me, and also some information on the 1VJ engine. Is there anything imparticular I should be looking for? Or should I be looking for a genuine 3AJ replacement before I put it all back together?

Cheers for any help.

Pat.

[Mezo]

Your engine is made up of parts that worked from previous models, it's the most common question asked by people new to these bikes thinking their bikes engines were cobbled together by the previous owner from older models.

If you look at the parts fiche for your bike (we have on file) you will see the part numbers go back years to previous models, if the parts worked they was simply carried forward to the next model complete with the "old" part numbers cast in to the part.

Mezo.

[jibber]

As Mezo says, the left case was carried over that's why it is identified as 1VJ, the right case was changed slightly so will be 3AJ, the barrel was changed so will be 3AJ. The 1VJ had a 2KF barrel iirc.

[jibber]

The 3AJ was slightly improved over the 1VJ, 1more cooling fun, improved lubrication to the gearbox (external oil feed) An extra Bolt for the rocker box and 2 of the head bolts are longer iirc, larger capacity oil pump also.

[Patrick]

Cheers for the info lads. That's good to know.
So I shouldn't expect anything different in the way of extra or different seals etc? That's my main concern, the plan is to split it today (broke my circlip pliers last night with one more to take off before I could open her up ) and replace everything that needs so I can get it back together and painted ASAP. I've got a full gasket and seal kit for the 3AJ but ill be bummed if I need to go shopping again.

[jibber]

if you have the 3AJ kit you should be covered