Re: dhadley help!
The number on a looper head is a casting/run/cut number which is different than the part number. In the looper world, one part number may cover several runs or cuts of heads. On the crossflow heads the casting number was the part number. That was way too simple. <br /><br />I prefer to have both heads the same cut number, -4's in your case but on anything other than a high performance boat it doesnt seem to matter.<br /><br />We have seen a lot of heads running hot lately due to build up in the water jackets. Especially Yamahas. It cant hurt to take the head off and clean it out. We prefer to glass bead the heads but yours is not the type that comes apart. Soak it in some good cleaner like Engine Tune and hopefully, if that is indeed why one is overheating, it will cure it.<br /><br />You might try swapping heads side to side and see if the problem follows the head. <br /><br />Good luck!