'86 Offshore Repower Problem, converting a 30" shaft to a 25

[Andrew93]

I bought a 1986 Offshore this time last year with its original 200hp Yamaha on an open transom. Over the winter I found a fair deal on a 1999 Yamaha 225hp OX66 with 0 hours on a rebuild and a 1 year warranty and figured how could I go wrong, RIGHT! I repowered the boat with the 225 and the mechanic rigged the new motor for me as well. As my luck has it the motor failed with 5.5 hours on it in June :bang. I have been less than satisfied with the mechanic and his reputation is pretty poor in my book. He pulled the heads back in June to discover a cracked cylinder and said he was going to make good of the situation. Here I am months later and he hasn't even touched the boat. I am now worried even if he does fix the motor it will no longer be reliable, his plan was to re-sleeve the block. I am about ready to cut my losses and pull the boat home and eat the money I spent on this motor.

Here is my question. Buying a brand new motor is out of the question for me at this time, but there is a 2001 Yamaha 225hp local to me for a pretty good price, better than the original one I bought, but has a 30" shaft. How hard would it be to use my junk 225 to convert the 30" to a 25" shaft. I was told by someone to swap the powerheads, but I do not want to do that, I want the 2001 serial numbers for the boat since the current motor has a damaged serial plate. It is early in the winter and I could just wait it out and hope something else comes along with a 25" shaft, but I hate to risk it and let this motor pass by.

Any thoughts and thanks in advance!

Andrew

 

[gw204]

Re: '86 Offshore Repower Problem, converting a 30" shaft to

Stick the '01 225 powerhead on the '99 225 midsection. Swap the transom bracket from the '01 to the '99 to get the SN to follow the powerhead. SN is on the little sticker to the left of the tilt tube in this photo...

...or...

See if the mechanic will give you a partial refund for the motor that blew. Take that money and buy the '01. They take some more money and have your transom rebuilt to 30". The cutouts were low on those boats and the end result will safer. Good chance it's at least partially rotten anyway. That's what I would do.

 

[VeroWing]

Re: '86 Offshore Repower Problem, converting a 30" shaft to

Some engines with long shafts have a 5" spacer tube added to the bottom of the midsection to accommodate the longer 30" shaft outdrive. You could just remove the 5" section and bolt the 25" lower on and you're done. Not sure if your Yamahas are this way, but I know various other brand outboards are. You could also switch driveshafts on outdrives too, but that is a little more involved.