New to me 1975 25hp Johnson

[jonmac3569]

bbguy,

I have the exact same motor. You can see my thread in my signature. I have went through several issues in the thread but a few more that are not in the thread so let me know if you have any issues. I don't know everything about the motor but there is a fair chance I have toyed around with it. About the only things I haven't messed with are the cylinders and and lower unit.

One thing that made a big difference in mine was changing the J4C plugs to J6C, hotter plug and ran much better. (thanks to a suggestion on this site) I had a thermostat that was failed open so it was running cold. Changed that and the plugs at the same time and running great now.

 

[baseball_guy_99]

Ya I was going to change the plugs. The ones that are in there now are NGKs.
I'm going to replace them with the champions. Thanks for the heads up on which ones to use.


Got the thermostat put back in last night. I'm going to fire it up this week and see how she runs.