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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I was working with about two months ago. I have advanced the

Customer Question

I was working with Jason about two months ago. I have advanced the timing on both port and starboard motors to 15 degrees (actually 18 ). The port motor now runs a lot better and can make the boat plane and run to a max speed of 30 mph. even with the starboard
down and not not running. It is a beast!! No luck with the starbd. The stbd can not make boat plane and will only run the boat to 8 MPH with the port engine up. To diagnose my problem, I ran the boat with the STBD carb covers out. When the motor maxes out
with the boat running at 8 MPH, I squeeze the primer bulb but no change. I push the choke pump key to squirt fuel in the carbs and no change. I spray quick start into each carb throat. When I spray on no 1,2 and 4 the rpms go down. When I spray on carb no
3, no change in rpm. Spraying a whole can of quick start does not change the RPM. Likewise when the engine is idling. Spraying just a little of quick start on carbs 1,2 and 4 will almost make the engine stall. Spraying a whole can into carb 3 does not change
the idling rpm. I check the compression on all 4 cylinders and the numbers run about 140 psi with a maximum variation of 5 psi. I check the spark on all four spark plugs by removing plug and grounding the plug and there is a very robust spark When engine is
running at idle, I also check spark with a timing light and the timing light flashes for all plugs. Examining the spark plugs visually show that spark plugs no 1,2 and 3 look normal. Very surprisingly, plug no 4 looks very clean and dry. All plugs are very
new. I switch carb no 1 with carb no 3 and do my spray test and do not get any different results. This indicates to me that the problem is not with the carburetor. I dismantle the carb assemblies so I can get access to the reed valves. There are 10 leaves
per cylinder for a total of 40 for the entire motor. I crank the motor and see all 40 reed valves popping open and close. Whatever reed valves I can see are clean, and don't show any damage or chips. I do not see any stuck open and I see ALL 40 leaves open
and close. I crank the motor and spray carb cleaner on the leaves that already look clean to start with. I feel silly cleaning something that looks clean but I go ahead and finish three cans of carb cleaner on the four reed valve assemblies but specially on
number three.I am ready to put motor together and fire it up and test it. I thought I would solicit your help at this time. Is there anything more I can do?? please let me know what you will charge me for this consultation before putting a lot of time on it.
I also need you to let me know how to set the idling/timimg on this motor. My boat needs a minimum of 85 HP to plane it. Both motors use to have a 21 inch pitch prop but I changed them to a 17 inch pitch to help with the planning matter.
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.

Hello, Jason here.

What kind of RPMS is the engine making with both engines running, and the boat going full speed?

Customer: replied 1 year ago.
Hello Jason thank you for your question. I do not have a working tachometer on board so I cant really answer you question. However the following info might help. The port motor can push the boat to a max speed of 30 mph. The stbd motor alone can push boat to a max of 8 MPH. with both motors running and the throttle lever pushed all the way forward, the boat hits 40 MPH. I can hear the stbd motor running really nice and developing good RPMs in this condition. In neutral I can gun the stbd motor to a very high RPM I estimate at least 5000 RPM but I only do that in very short bursts. If you want to call me I can be reached at(###) ###-####.I live in the san Francisco Bay area in California. Thank you Jojo
Expert:  Jason replied 1 year ago.

Hi Jojo. Phone service is available but it is an extra charge. I will send you the offer information over for it, if you would like a call you can accept that offer and I can give you a ring a little later today.


Customer: replied 1 year ago.
Hello jason, i would decline phone call offer for now. I actually prefer written communication since that provides me something to refer to in the future. Thank ypu and i am looking forward to your help. By the way please dont forget to address my question on how to set timing at idling and with a garden hose attachment. Idling spec for my boat is done in the water and in forward gear.