Re: 2002 MERC 90 TWO STROKE
Hi rsgonza,<br />I have a 2000 model merc 90hp saltwater 2st, it outperforms the merc 90hp inline six that I replaced after 21 years use, all in saltwater.<br /><br />the 3cyl 90 uses about 1.5gls of fuel less over an average 30 mile run in open sea (uses about 4 1/2 gls), it is able to run 2" larger pitch prop as it has more torque and power also is 5mph higher at WOT of 5,350 and also 5mph higher at a cruising rpm of 4,400, this is pushing a deep V glass h/cabin boat with an average weight of about 2,600lbs when loaded with gear.<br /><br />As bryanredfish notes there can be a tendency to have a rough idle but they go well over 2,000 rpm. I have mentioned on previous posts the carbs seem to be very sensitive to idle mixture settings and mine did start to idle roughly after about 50 hrs of use. I found this problem disappeared completely by setting idle speed and mixture by the book and making the mixture slightly richer by adding no more than another 1/8 of a turn out on the screws, this has made all the difference and has given me a much smoother idle.<br /><br />Another item that seems to make a difference is the type of prop, I ran a 15" pitch ss prop on the old six, but running it on the 3 cyl, there was more vibration at idle & slow speeds. I tried 16" and 18" pitch ss props with similar vibration, I now run a 17" pitch aluminium with very smooth idle and no vibration at all at trolling speed. I don't know if it is related to the gearbox ratios as these motors run 2.3 which is a bit different to most of the other larger mercs which are around 1.8 to 2.<br /><br />I am more than satisfied with this motor both with fuel consumption and performance and nobody in this part of the world seems to have any problems with corrosion contrary to some of the posts I read, and we run exclusively in high temperature and humidity conditions in saltwater only<br /><br />BOB
