Originally Posted by Gledhill
The 90 has been apart of a sea scout group from new but has been stood for quite a number of years hence there's only 137 hours on the clock.
It was a friend who bought it off the sea scouts last year all the jets in the carbs were gummed up so he decided instead of re jetting the engine he would put a brand new set of carbs on converting it from the 75 to the 90 by just winding up the timing mark to the next notch. My 70 is a 1989 model and the 90 is a 2004 model he saying £1500 and I can swop them over just don't want to do it if there's not a significant increase in power I would like to be close to the 45-50mph mark at WOT.
Its not a 90 then it's a 75 running too rich and over advanced.
The carbs on a 90 are identical to a 75 but running larger mains. You need the high compression cylinder head and also a new exhaust tuner to convert it to a 90.
So unless you do that you are probably going to go slower.
And if it is an 89 not 99 then the control box linkage needs changing