Originally Posted by Zecatfish
The TT600/XT600 uses a different manifold from the XT550. The 550 might work on the 600, but not the other way around.
I think your going to find that the XT600 carb is going to be jetted a bit rich for the 550 mill too.
I got a perfectly working 550 carb I'll trade you if it is. Its to lean on the TT600 mill in my 550.
Yes, jetting will be an issue with an engine swap. Anyone who plans to use overbore, aftermarket intake or exhaust etc should think about rejetting immediately.
Thanks for the tip about the manifold, I did not attend to swap these; only the carburetor.