150 I6 needs more kick to beat the 115hp I6

first off, these motors kick ***. minimal maintenance over the years they start and run great !!!

the 115 is a champ and pulls up to and past 5000 with a kick at about 4500 that drops the rpm down to about 3900-4000 without slowing down !!!! its crazy. this motor is a cdi ignition setup from early 80's

the 150 is 1974ish outboard. started from the dead it ran great. There is some fine tuning to this as to why I cant pass this 115 doing like 65mph. the plugs are all new....couldnt win, carbs and engine compartment look spotless clean. I dont know where to look but the motor seems like it needs some nitrous directly shot into the carbs to act how it did 20 years ago. my guess is the revs wont pass 4500. weak distributor or am i looking into something else ? gas and plugs are brand new !

also can anyone explain the 2speed like shift in the 115? its really cool how it does that, smokes any johnson around


to add to the info. the 150 has a 3 blade prop (i dont know the specs) the 115 has a high 5 aluminum prop. I suspected the 3blade on the 115 would be faster top speed. am I right ? id like to put the 5 on the 150 and the 3 on the 115 and see. worth while ?


Iboats

Re: 150 I6 needs more kick to beat the 115hp I6

I dont know where to look but the motor seems like it needs some nitrous directly shot into the carbs to act how it did 20 years ago.

Click to expand...

You included lots of questions/comments in your post above but I will respond only to the one quoted above....

There are lots of possible causes for lost power and correctly guessing at the specific reason(s) is highly unlikely. A systematic approach is often the better way to go. I suggest that you first do a compression test to see if low compression is causing a power loss. If the compression is OK, then I would next suggest doing a link and sync. If still no improvement after the link and sync, then a carb cleaning would be the next step. If none of the above helps, then post back with what you did do and more advice can be provided.

Re: 150 I6 needs more kick to beat the 115hp I6

great thanks for the help ! ill get in and do the compression test, i am kind of suspecting one lower compression piston causing it to slow down.

if not ill have to learn how to do a lync n sync on the motor and be sure the carbs are FULLY open at wot. a very fun boat that starts like a champ. how many hours till this 35 year old dizzy craps out on me ? lol