Last year I have bought a Honda BF20 2005 with standard 4 blade prop, but this engine was never able to get higher than 3000rpm, always at some 2950rpm with the lightest load.
I have a 12ft Excel 365 HD inflatable, total weight about 100kg, plus some gear, fuel tank, 2-3 bottles of vodka and myself. Total load would be some 250kd max. Still the engine was never revving very high. The tacho comes from eBay, btw. Top speed at 22knts.
I have replaced the prop for a Solas 3 blades 11 pitch, to get more speed. The revs dropped by some 200rpm only. But I got 1knt more, no big deal.
I dropped my engine by a local Honda dealer, which insured he is unable to adjust the correct rpm unless have the engine mounted on a boat and goung WOT. I have hard time to believe it, it could just run it in a tank and get at least some basic rpm readings, what he refused to do. Anyway, even in a tank with no load it does never go above 2800-2900.
The engine is in a very good condition, and since I bought it I use SeaFoam in every tank. Very happy with the SeaFoam results btw, never had a clogged carb.
Could anyone give me a tip on what should I look to adjust my rpm? The Honda dealer was useless and not very helpful, replaced 2 spark plugs without my consent, adjusted the tiny screw (fuel mix) and charged me £75.00 for it. The previous plugs had only 4 hours. Very disappointed.
Any help will be very appreciated.
PS bought another tacho, just in case, to check the actual one.