Honda 90 newbie questions

Ken O

Ken O

Member
We will soon own a Honda BF90A attached to a C-Dory 22 Cruiser. Both are 1990 vintage. The boat and motor have been in storage for several years. We will be bringing the boat to Montana for a year or so for some outfitting and then move it to its permanent home in Juneau. There is no kicker at present, but we will be adding one. We are not addressing the kicker here.

My questions relate to the Honda main:
1) Should I change the oil right away or before the boat goes in the water?
2) Same question about the lower unit oil?
3) What else should I inspect, service, or change out (raw water impeller comes to mind)?
4) Is it worth getting a 55 gallon drum and running it some? If so, how often?
5) What spare parts should I carry?

I'm very comfortable working on all types of gasoline engines in vehicles, but this will be my first outboard. My previous marine engines are kayak paddles... Thanks a bunch!
 
Hi, greetings from Canada, and congrats on your purchase! The answers, to some degree, depend. Have the fluids been changed very recently? Synthetic oil lasts a very long time but dino oil does break down. It is easy and cheap insurance to change the oil and filter. I recommend getting a manual oil extraction pump, really makes oil changes easier - I've used a West Marine one for years without issue.

The oil in the leg is CRITICAL to change prior to freezing weather in case water has gotten into the gear case through a seal problem. If water did get in there it does expand when freezing with enough pressure to crack the gearbox or blow seals out or both. On that note, for an older motor it is well worth having the leg pressure-tested and re-sealed if necessary (and not all that hard to do yourself).

That is a carbureted motor. They are quite reliable but don't like sitting unused. Keep fresh fuel in with a lot of marine-grade fuel preservative. Run regularly during storage (monthly) either in a barrel or with mouse ears. Alternatively prepare the motor for storage by properly draining and cleaning the carbs - you may need to install carb kits, and you will need carb cleaner, jet cleaning tools, etc. to do this properly.

For storing the motor, if you are not going to run it regularly then pull the plugs and fog cylinders. This is not necessary if you run it regularly. I also like to spray anti-corrosion spray over all parts of the motor and wiring, this is good preventative maintenance for any outboard which sees duty in the saltchuck.

If you do not know when the impeller was changed, definitely change that out. They do degrade both with use and with time. Sometimes you can get away with just the impeller, sometimes you need the complete kit including wear plate and seals so get the kit. Takes around an hour to do yourself.

Remove the prop and clean and grease splines with waterproof marine grease before re-installing. If any damage this is a good time to send it away for repair, and to check that the center rubber hub is still holding properly.

Spares: oil and filter, spark plugs (pre-gap them). Timing belt? I don't know that motor and am not sure if this is field-serviceable without special tools. Ignition parts tend to fail with time as do electronic controllers. And so do trim/tilt electric and hydraulic motors. A spare prop is also important to keep on board. It's not a bad idea to have extras of the related prop nut, washers, waterproof grease, and cotter pin - easy enough to drop overboard when changing at sea.

Best of luck with it all!

Charles
 
Hi Charles,

Thanks a bunch for the thorough answers. I'll check West Marine for the products. I may have questions on sources if I don't find something there. We have a Honda outboard dealer in Billings, but they are probably not familiar with anything salty. I have changed the timing belt on that same engine, but it was in an Accord, so the timing belt might be harder to get at in the outboard. Again, thanks for the help.
 
You're most welcome! On reflection, I would say it is a real drag to work on an outboard when you are on a trip, at sea, even if at a dock. Preventative maintenance including replacing vulnerable parts (particularly those which are difficult to work on or require special tools) is the way to go. That said, modern 4 strokes are really amazingly reliable. But if your main is an older motor, plan for the possibility of break downs. I spent my youth commercial fishing and the one big lesson I learned is that if something can break it will do so, often at the worst possible time. Have a really reliable auxiliary motor, VHF etc.

Charles
 
I would go ahead and change the engine oil, lower unit gear oil, and change the impeller. I just did it on my Honda 90 last weekend and its all a pretty quick job. Use a ratchet strap for putting the lower unit back on if your doing it by yourself. That was the trick for me, as it's heavy and I was working alone.

Your motor is a really great one. Their achilles heal is the carb jets are very small. When you're not running your engine often, unplug the fuel line from the engine and let it run al the fuel out of the carbs at the end of the day. Then take a paper towel and place under the drain petcocks on each of the carbs individually and using a screw driver, drain the remaining fuel out. If you do that, you'll never have a problem with those carbs. You shouldn't have any trouble leaving it for a long period if theres no fuel in the carbs.
 
Ken O,
Something else that will fail and not allow the engine to get up to temperature, as well as allow condensation to build up in the crankcase, which will eventually show an increase amount of oil on the dipstick, is the thermostat.
This is usually not a fun item to replace, because the thermostat is located at the top of the water-cooling manifold and the top two bolts hold the cover for the thermostat. The remainder of the manifold is intended to remain in place, but now the gasket behind the waterjacket manifold, has been compromised, because of removing these two bolts. Sometimes, the thermostat housing and it's gasket can be removed to install a new thermostat, and will not cause the water jacket manifold to leak, but sometimes, the entire water jacket manifold must be removed, so that it's gasket can be replaced. The thing that is a pain is that if the engine was run in salt water, most of these fasteners and difficult to remove and they sometimes break. Just remember that all of your outboard fasteners should be coated with an anti seize, such as Tef-Gel. If they were coated in Tef-Gel at the beginning, they would always come apart like new.
Anyway, please do eventually add this to your future maintenance list. You can view the thermostat and the water jacket manifold here: www.boats.net

https://www.boats.net/catalog/honda/out ... thermostat
 
Charles-- Do you have a link to the anti-corrosion spray you mentioned? I think I've found everything else that has been mentioned. Thanks everyone.
 
Excellent advise as above. With the Honda 90, unless I was certain I was going to run the engine in a couple of weeks, I always drained the carburetors. They are difficult to get off and work in if you have to rebuild.

Any impeller which has not been used in a couple of years, will most likely develop a "set", so I would change that also. However, I probably would not do that until the spring, if you are not going to use the boat until then.

As for a 50 gallon drum--most of us run the 90's on the muffs which fit onto the water intakes of the lower unit. Be sure that a there a good seal on both sides, so that the majority of the water is drawn into the pump.

If the boat has been used in salt water, Ii would consider the thermostat inspection/replacement as an essential...Look for corrosion while you are there.
 
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