Re: Looper 225 Powerhead swap: Compatability
I did a similar swap with a 1996 powerhead to a 1992. I'm sure that There will be some differences. Nothing too crazy, but need to be addressed. You will need to get rid of the thermostat Bypass valves and existing thermostats. Replace them with thermostats and covers from a 1989 70hp. Another problem is the Tell tale. The newer model uses a molded grommet that taps into What I believe is called the exhaust adapter. Dead center aft, where the 2 exhaust relief ports are. The older block ( In my case 1992) Had a tell tale tapped into the top port side of the water jacket just under the powerpack. This did 2 things for that year of crankcase: It gave you an indication of cooling system operation, and (most importantly) Bled the air out of the top of the crankcase. The newer Crankcases dealt with air in the crankcase by use of a valve that replaced the tell tale port. If you plug the tell tale port on the older powerhead and try to use the newer style tell tale instead, you will eventually cook something. Rectifier, or top pistons due to lack of cooling water in the upper part of the crankcase. It is a good idea to keep the older style tell tale fitting. It wont kill you to have 2 tell tales, but your water pressure may suffer if you use anything more than 3/32 hose for the tell tale. Monitor the starboard cylinder head temp closely if your water pressure is affected. The thermostat is higher on that side and can run dry if the pressure is too low at idle. If this is your case, you can pull off that rubber exhaust grommet and plug the pisser from the inside with something.
Something else to consider: The 2000 carbs are jetted for a finger ported crankcase. That older crankcase I believe is not finger ported. I dont know how much of a difference it will make for you, but it made a difference in my case. Make sure your powerhead to adapter mating surface is clean and free of debris. Small pieces of scraped off gasket sometimes fall into the adapter. These pieces can become lodged in cooling passages restricting water flow. This was my experience in my swap some may be relevant to you. Jason
