Thanks for the input , Ill try to answer the best I can, I purchased the boat only 6 months ago so I don,t have a lot of info.
Is it safe to assume you have a Yanmar YSB/YSE/YSM-8 with the typical 2:1 gear ratio?
YSM 8 unsure of the gear ratio
Is it safe to assume you have a CAL 2-25 when your profile boat type is "2 25"?
I have a Yamaha 25 1978
What propeller diameter and pitch do you have?
unknown but I have no reason to beleave it is any different than the stock one
What is your maximum no-load (neutral) motor RPM? The YS_8 series governor should limit it to 3400 RPM.
I dont have a tach so it is hard to tell.
What is your maximum loaded motor RPM? It should be 3200 RPM.
unknown
I believe that black smoke is usually an indication of motor overloading. Did you perform the motor work to try to solve the black smoke problem?
no, I blew a head gasket so I pulled the head, cleaned and lapped the valves, cleaned the exhaust elbow(that was not very dirty) and put her back together.. A prety easy job for the most part.
If you cannot reach 3200 RPM under full load your propeller is probably too large and/or has too much pitch. Most sail boats with a displacement of around 5000 lb, 22 ft LWL, 8 HP nominal and a propeller speed of 1500 RPM use a 12" diameter propeller with 7" pitch.
I'll have to wait until I pull her out to check the pitch..
I have an YSM12 in my CAL 2-25 with a Campbell Sailor CS3LH12x7x1 propeller. The boat originally came with a CS3LH13x9x1 that could not get to full load speed, caused black smoke and motor overheating. It is usually not expensive to reduce a propeller diameter and/or adjust the pitch.
Thanks for all the info. I never checked the pump timing, do you think this may be a problem?