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Wednesday, April 04, 2012

Small Boat Diversion: It Keeps Going... and going.. and going...

A diversion courtesy of  "the other boat"...

Last year we took a couple weeks vacation aboard our small 28 footer. Everything went well in that nothing major broke, nor were there any big emergencies. But our dinghy's outboard motor, having been neglected for years, started fighting back. It hit us with an inability to idle, and just plain die at speed after only a few minutes. This behavior forced us to row to our destinations, or hitch a tow from a local neighbor and their dinghy (at great humiliation). Upon return, I was determined to get this resolved by the following season. The time has come.
27 year old outboard motor
The outboard motor is an old Honda 2HP four stroke. It "came with the boat" and is known to date back to at least 1985 (27 years old). The serial number indicates it as one of the first 700 produced by Honda, according to the dealer. The motor has always started with a couple pulls of the cord despite having been abused and neglected from stupid owner tricks such as:
  1. running an entire season with nearly no crankcase oil
  2. wrapping eel grass around the prop and stalling (many times)
  3. sucking up mud from shallow mud flats, clogging the cooling system, and overheating (many times)
  4. burning old gasoline
  5. changing crankcase oil on an interval of "years" (see #1)
  6. running over rocks and shearing off the prop.
  7. overfilling the crankcase with oil (upon discovery of #1)
  8. rinsing/flushing with freshwater after each trip, NOT (never, ever)
Honda. the ONLY maker of small four stroke outboards in 1985 (every other make was 2-stroke)
We had the motor tuned-up by a shop over ten years ago. I think that was the only time it has been seen by a "professional". Every year at the boat show, we would take a look at Honda's current 2HP offering (not much different than ours). Besides the $900 price tag, we would walk away telling ourselves we "can" keep the old motor running if we just keep it serviced (which we would never do). Anyway, having worked on our own cars and motorcycles (many of them Hondas), and being in possession of the shop manual (all twenty five pages), I finally set out to fix it give some TLC. How hard can it be?

Being a 2 horse, this engine is very simple: crankcase, one piston, two valves, small carburetor, bolt-on solid state electronic capacitance spark ignition (i.e. no points). The symptoms suggested a fuel problem. Noticing the carburetor was badly rusted (adjustment screws were rusted shut) I picked the following strategy: replace the carburetor and fuel filter. This is effectively replacing the entire fuel system for such a small engine and costs about $100 in parts.
Reassembled with new carburetor (lower left)
Some non-critical bolt heads sheared off, due to rust and corrosion, during disassembly. I pulled the cylinder head, checked valve clearances, removed the valves and cleaned up everything with solvent and a wire brush. I reassembled everything with the new carburetor and gaskets, cleaned out the gas tank and changed the fuel filter. Topped up the tank with fresh fuel, and with four pulls of the cord it fires up! Make some small adjustments to the carburetor and it is purring like it used to (as much as a single cylinder four stroke can purr). I love this little motor. I hope it never (completely) dies. If and when it does, I will buy another Honda.

So check that off the list. It should last another 25 years of neglect, right? The real test will be in the dinghy, on a real trip, out in the middle of nowhere, a mile or two from the boat. Maybe this summer.

1 comment:

Tom said...

They sure do, good decision to refurbish, we hope ours (new 2004) will last that long!