The lower got some service, now time for the upper.
An issue that has plagued this motor since I got it has been the loss of power later in the day. What is causing it and how do I fix it?
I’m using a manual from SELOC that covers every aspect of this boat motor. It has every step to fully rebuild it. However, it does make some assumptions, such as assuming you have some mechanic skills. The instructions require an understanding of how these parts work together, how to use tools to disassemble/reassemble, and some knowledge of best practices when working on machines.
There was a small section on how to tune the carburetors. The procedure is to have the motor running, preferably in water, and in gear at idle. You turn the idle adjustment out until the motor starts to sputter. This is too rich (too much fuel). You then turn the idle adjustment in until the motor sputters, and count the turns. This is too lean (not enough fuel). You then turn the idle adjustment to halfway between these two points. By counting turns, you can figure out what is half way. It may not take a complete turn of the screw to reach either point, so it suggest counting by 1/4 turns.
Once you have the idle set, you take the boat out on the water and run the throttle to see how it behaves. If it bogs down when you throw the throttle forward, it might be too rich, so turn the idle adjustment 1/4 turn toward lean and try again.
If it seems to run out of power before reaching full throttle, it may be lean, so turn the idle adjustment 1/4 turn to rich and try again.
This is where experience comes into play. This experience I don’t have, so I’m learning. I like learning, but this can be a bit frustrating. The manual assumes that the reader has this knowledge.
We know the boat idles a little rough. It runs, but not super awesome. Top speed has been 35MPH, which from what I’ve read, is low. This boat and motor should be able to do 50+ MPH. It also bogs down at the end of the day when it is time to put it on the trailer to go home.
The lake is a bit of a drive away, and it was cold out when I was working on it. I figured I’d at least get a start on the tune and see how it went when it got warmer. I’d finish it up on the next trip to the lake. This was my plan, anyway.
One I got the work done on the lower, I connected up the flush “ears” to run water through the motor as it ran. I wish I had a garbage can or something I could submerge the lower in, but I lacked it that day. At least the motor would be cooled as I worked on it.
I squeezed the priming bulb a couple of times to get the fuel up to the carbs. It took a few squeezes, so the line was empty. I cranked the motor a bit and with a little throttle and some choke, it sputtered to life. I let it run a few minutes to warm up, and to verify water was flowing from the telltale.
Following the above steps, I found the top two carbs to be a right in the middle, but perhaps a little rich. The bottom carb was very rich, so it is now leaned out. Keep in mind I did this with no load on the motor, so I’ll have to repeat it on the water.
See that screw in the middle, just to the right of the intake? The one that is facing forward and looks like it is easily accessible? Yeah, that’s the idle mixture screw.
What is interesting is the upper 4 cylinders showed a lot of carbon buildup on the pistons. The bottom two were shiny. I had assumed the lower carb was running lean, so running hotter and burning the carbon off. Perhaps it is just the opposite. Perhaps it was running rich and putting a LOT of solvent on those two pistons and cleaning them off? I have been running some Seafoam in the tank, especially during the last trip, so maybe?
There is a bit of a change in how it is now running.
Here is before:
Here is after:
A little smoother.
I buttoned everything up and waited for a warmer day to get out to the lake. Sadly, that day didn’t come. The rest of the month got busy and the only warmish day was spent being responsible. Oh well.
Once I admitted to myself that I wouldn’t be taking it out on a lake until spring, I decided to winterize the motor. The procedure is pretty simple. Get some engine fog and follow the directions.
In this case, it was to get the engine up to running temperature, then to spray the fog into each carb until the motor sputtered. I did this 3 times, just to make sure there was plenty of oil in the bearings and cylinder walls. The last step is to take out the spark plugs and give a good spray into each cylinder. I had to crank the motor a couple of times to get each piston to bottom dead center to have enough room to get a good coat of spray.
What’s interesting during this process is that I may have discovered why the motor has a hard time late in the day when I’m heading back to the marina. I primed the motor using the fuel bulb, but this time I gave it a couple of extra squeezes to really make sure gas was up in there. I saw fuel leaking out of at least one carburetor as I did this.
I was able to get the motor started, but it took high throttle to do it. That and a LOT of cranking. Once it was lit, it didn’t want to run without some throttle. This is just like what happened twice on the lake. I did the fog procedure with the engine not wanting to run right, but got it done.
This does lead me to think the carbs will need a rebuild. At the very least, the floats and float valves need to be inspected or just replaced. The float is used on a carburetor to make sure there is enough fuel available to run the motor, especially when fuel delivery might be intermittent. It also give the carb a set point for the balance of gravity, vacuum, and draw to make sure the fuel is consistently and evenly delivered to the cylinders.
The additional motor work will need to wait for spring. Unless I decide to farm the work out to somebody else over winter. Boat mechanics get remarkably less busy during this time of year.
Once I do get it running right, I need to decide if I’m going to keep this boat or get another one. Right now, I’m leaning towards getting a newer boat, or at least one in better shape. Then again, it is interesting to me to work on this one and make it better. The balance is this: You can take a $2500 boat and put $1000 into it and have a really good $2500 boat. Is it worth it?