I just bought an older B100 from a guy at work. It belonged to his father, has very low (around 30) hours, never seen salt water and has sat in storage for 10-15 years.
While it was in storage, it sat flat with the prop down, so the plugs are loaded with clean oil and won't spark, but it has a stong blue spark when a screwdriver is inserted. I want to get it running this weekend and will change plugs, engine and lower unit oil.

My first question is, what year was this engine built? Tag number is B100-1005057

2nd, what if anything else should I change or replace?

3rd, Will the original impeller be okay?

4th, where can I find a plug that goes into the 12v 60 watt plug in on the engine and will this be ok to charge a deepcycle battery?

Thank you for your time.
Ken

Couldn't find that serial number B100-1005057, if it happens to be BF100-1005057 then it's a 1978.
You might want change impeller and clean carb.
The charge plug is part number 31652-881-004

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Thank you very much!

I will check to see if it is "B" or "BF" when I get home tonight. I got the number off the tag near the engine mount.

Do you have the number for the impeller and will I need gaskets or any other parts when I change the impeller? Is there a kit for the impeller change?

Thanks again.
Ken

Honda Outboard Parts Pre-1997 BF100 LA OUTBOARD ENGINE, JPN, VIN# BF100-1000001 TO BF100-1020309 WATER PUMP + VERTICAL SHAFT Diagram

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If that's the one with the points magneto igntion (rubber cap over cam pulley that pulls off revealing the points) then you might want to remove the pulley and verify the mechanical spark advance weights are still free. Mine were stuck causing poor performance.

Have a look at my post. You're going to want to pull the impeller out first before replacing it. If you're into a new driveshaft like me, you'll need a different impeller.

Pain in the neck removing the l/u due to the shift rod connection. Put engine in neutral. Remove the rectifier and the detent spring/roller. Remove cotter pin holding shift pin in place. Remove shift pin. Unscrew top of shift rod until it comes off. Then remove the l/u bolts (6) and drop it off.

Reassembly: Line up and bolt on. Verify your in neutral (turn prop). Screw in top of shift rod all the way, then back 4.5 turns. Install pin (it should line up).

I also adjusted the valve clearances while I was at it & lubed everything up. Didn't bother with the spark plugs: they were fine once I cleaned the oil off them.

60W will keep a battery topped up but it will not charge one. 5 amps (60W) will take well over 10 hours of WOT running to completely charge a battery.

Thank you for the information.

I cleaned the carb, changed the plugs and put a few ounces of Seafoam in the fresh gas and it fired right up. I ran the engine about 20 minutes and the water coming from the pee tube seemed ok at first, but I shut it down when I heard what sounded like a nail being pulled from wood and the volume of water seemed to decrease a little. I also noticed that the water put out a lot of steam, but then again the outside temp is in the upper 30's and I seemed to be puting out a fair amount of steam as well.

I double checked the number on the metal tag and it very clearly says B100-1005057 The "B" is painted and the numbers are stamped. Could there be another number somewhere else?

Is it possible that the early motors just had "B" even though it was a "BF"? The owners manual that came with this engine was printed in 1977 and on page 5 it says the engine is a 9.9 horsepower BF100.

I noticed the "Pre-1997 BF100 LA" and "Pre-1997 BF100 SA" does the "LA" stand for long shaft and "SA" stand for short shaft? If it does, I have a short shaft.

Do the #3 impeller cover and #4 impeller gaskets generally stay intact with the impeller change or should I buy these as well.

I'm sorry about what may be dumb questions, but other than points and plugs, I've never really worked on outboard engines.

One last dumb question and I'll leave you alone. I have a chance to buy a factory service manual for this engine. With all the cars and trucks that I've worked on, the factory service manuals have always been better than the aftermarket manuals I have found. Would this be true for this Honda outboard as well or is there an aftermarket manual that would be better?

Once again I want to thank you for your time.
Ken

Thank you for the information.

It sounds like we may have the same motors. Mine is gray with an orange/red flywheel.

Other than a spider thinking he was going to catch dinner under the engine cover, the engine is pretty clean and has never been in salt water. The zinc looks like new and when I pulled the carb apart, with the exception of a little discoloration in the lowest portion of the float bowl, it looked like new.

In the past, when I've changed points on a couple old Johnson engines, I found it to be a real pain in the neck to get the flywheels off and I'm not looking forward to pulling the flywheel on this engine. Do you think there is much chance of the mechanical spark advance weights being froze up on this clean, low hour engine, that hasn't been in salt water?

When your weights were froze up, did you mainly have problems making power and reving up?

I was hoping to hold off on pulling the impeller until I had a service manual and the needed parts in hand. Would fresh water be able to do enough damage to the shaft that would cause it to need replacing with so few hours on the engine?

I'll take a closer look at the engine tomorrow and see if I'm up to pulling the shaft before I get a manual.

Thank you for your help. I'll check out your post.
Ken

Yeah, I'm sure it's pretty close to the same engine except mine came with mud wasps (perhaps the spider was on to something?). I don't know why the very early ones are B100s instead of BF100s, but there's no functional difference than I can find between them and the earliest BF100s.

I found the weights before running the engine much so I can't really say what the problem was other than the previous owner's complaints. It was a neglectorino so it needed a good going over before seeing service. Seafoam too as I think at least one previous owner must have been mixing 2-stroke oil! (I had pretty heavy leakage past one of the intake valves caused by a hunk of carbon. Now it's very, very good.

This outboard was shipped from the great lakes but the lower shaft was still rusted quite badly where the chrome was damaged. Honda in their wisdom decided mixing carbon steel, stainless, aluminium, chrome and bronze in the water pump was a good idea. But it had been mounted to a sailboat and I don't think they could tilt it out of the water: there's mineral stains all over the L/U.

Removing the lower driveshaft from the upper required quite a bit of work. In the end I drilled a hole in the top of the upper driveshaft (it's hollow), inserted a rod and pounded out the lower with liberal applications of heat and penetrating oil. I managed to save the water pump housing this way though. (It's trapped between the upper and lower). If it were mine I'd have it apart frequently just to grease that joint to prevent it from seizing.

One thing you'll like about the 4-stroke is that the points are underneath the cam pulley rather than the flywheel. You don't even have to remove the pulley to set them (just one set, since it's wasted spark on the other cylinder), just pull the rubber cover off the top.

I scanned part of the OEM manual. It's not ordered or indexed or anything, but if you'd like it just email me at paul.moir@gmail.com . I got the most important sections for basic maintenance, etc.

Good news and bad news.

I dropped the l/u per moir's instructions (thanks, it came apart like a dream) and the shaft and everything looks fine.

The bad news is one of the 4 bolts that holds the impeller housing broke

It looks like it is sticking out of the case a little, but it is inside the long collar that does not want to come off. I'm sure I could just use pliers and pull the collar off, but, wouldn't you know it, it appears that his collar is no longer available

The impeller looks good and is the type that uses a key.

I have no idea what the noise was and I'm starting to think the neighbor may have been tearing something apart. I was inside my shop with the engine running outside when I heard the noise.

If I bugger up the collar, I may be able to buy 2 of the short ones and grind 1 down for the correct height.

Time to use the collar to my advantage and fill it with a penetrent.

Hope I can get that bolt out.

While I'm in there I might as well replace the 30+ year old seals.

Does "LA Outboard" stand for long shaft and "SA Outboard" stand for short shaft? Not sure if there will be any difference, but I guess I should know before I order my parts.

Thank you for your help.
Ken

I'm pretty sure. I'll check in a few minutes.

When reassembling put a little sealant on all the bolts' threads and that won't happen next time. Otherwise it's de rigeur working on outboards I'm afraid!

Normal penetrating oil doesn't seem to work as the corrosion holding it is usually aluminium oxide and there's no great way to bust that, unlike steel corrosion. Heat (lots, like from a MAPP fired torch, propane alone won't cut it) does work very well but there you run the risk of cooking the driveshaft seal. You may end up resorting to drilling it out. *Do not attempt an ez-out or it will make the situation far worse!*

As far as I can tell the collars just help align the water pump housing. If your careful assembling it, I really don't see the point. A lot of outboards don't use them.

I just remembered something: the original thermostat for the outboards gets replaced with a colder one. The original maintains too high a temperature causing excessive calcium deposits in the block. That's really a salt-water problem more than a fresh water, though I understand some lakes can be bad for it.