Re: Mercury bogging ,is it common?
hello<br /> having worked with and on the 4 stroke motors for the past 10 years or so for honda and suzuki and yamaha and merc I have not really seen a design flaw. I see a lot of two stroke techs that just cant quite make the change to a 4 stroke. a certain amount of "bog" is normal and more pronounced at low speeds. its also called throttle lag. 4 strokes only produce a power stroke every other piston cycle not every cycle like a 2 stroke. there for they only produce a intake vacum cycle every other piston cycle. that is why 4 strokes need some type of accelerator pump system to force the mix richer during rapid throttle movements and a 2 cycle does not. before I blamed it on a motor design flaw I would have to have a session with a dyno or a test wheel at a minimum to make sure the motor made the correct power under load with a known accurate shop tachometer. you would not belive the amount of engines I work on that were never set up correctly from the factory or the dealer. remember most riggers make minimum wage and really have no training. if you pay peanuts you get monkeys.<br /> you need to find someone that has the test equipment,dyno and/or a test wheel, that can duplicate your problem while the engine is running under load. most bog problems on a 4 stroke at rapid throttle opening are lean conditions due to the fact that the intake runners are fairly large and we are just not moving a lot of fuel. that motor should have an accelerator pump or enrichment device. I am not going to hunt through all my manuals today. but it does have the circuits. have you tested fuel pressure between the pump and the carbs, and are the floats set correctly. the motor design is capeable of smooth acceleration but at low speeds and rapid throttle opening it will have some lag. <br /> good luck and keep posting
