1979/1980 Yamaha 5BS 5HP OUTBOARD

Even Chance

Even Chance

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Lads n lasses,
I have obtained a nice old aircooled Yamaha 5BS outboard. It was runnning great and is a powerful engine for its size/rating, but it suddenly stopped the other day. I can no longer get a spark. Is there any info/wiring diagrams/manuals about that can help me out please?
Number is :- 5BS 661L 38926

I have tried getting into the points with no luck, but that was not in a very determined way yet.;) Maybe tonight...
Coil impedance readings etc??
I have a parts listing downloaded already, but it doesnt give any service info.

Help would be very much appreciated.
Thanks:)
 
Could not find out anything about this model

Points ignition you say. Single cylinder presumably since you refer to spark in the singular

Obviously check the points,

Condenser could be faulty but the only times I have known them fail it has been a gradual process giving a weak spark and making them progressively more difficult to start.

Check primary and secondary coil windings for continuity. Resistance values not particularly meaningful because they are likely to fail due to insulation breakdown and shorting between adjacent turns.

If a coil looks manky it is probably duff!

HT lead ??

Have you checked the stop button ... assuming it has one.


If its the model i think it may be ( mid to late 1970s) it was imported also rebadged as a Mariner.


You should be able access the points through openings in the flywheel but to do more you will need to pull the flywheel. I think you will need a harmonic balancer puller that bolts onto the flywheel or you will damage the flywheel.

It might be possible to get it off using the method used for Seagull flywheels ( See the Saving-old-Seagulls website)

Watch out for the key in the crankshaft
 
Last edited:
Thanks for the info. Coil appears ok. Ive checked the windings. Still have to delve deeper into the points tho. I will let you know the results.
Had the condenser go on a 998 mini years ago. Went through 3 sets of points before changing it out and voila:- no more melted points!!

Was thinking about trying a voltage thru the coil to test it properly. I have a variable Power supply, any ideas on voltage to try?
 
Well, I took it all to bits last night, and removed the flywheel with some small 2-leg pullers I have (VERY carefully!) It came off easily enough.
I checked the condenser while it was isolated. (using a Fluke 179 dmm set to measure capacitance). It was OK.
I then had a good look at the points and gave them a wee polish up to remove carbon deposits. They werent bad at all, and were opening just fine. I replaced them and set the gap.
I then removed the ignition coil and metered it. It also appeared just fine.
There were no apparent broken connections or wires as far as I could tell.
I replaced the flywheel, turned it over and got a spark!!?? I put it all back together and it ran beautifully, as before.
Now I have a potential intermittent fault as I could find no reasonable fault. (hopefully its ok tho- fingers crossed!)
Im going to put it on the inflatable and take it a run round the harbour for a while to see how it goes this weekend.
 
Even Chance said:
Well, I took it all to bits last night, and removed the flywheel with some small 2-leg pullers I have (VERY carefully!) It came off easily enough.
I checked the condenser while it was isolated. (using a Fluke 179 dmm set to measure capacitance). It was OK.
I then had a good look at the points and gave them a wee polish up to remove carbon deposits. They werent bad at all, and were opening just fine. I replaced them and set the gap.
I then removed the ignition coil and metered it. It also appeared just fine.
There were no apparent broken connections or wires as far as I could tell.
I replaced the flywheel, turned it over and got a spark!!?? I put it all back together and it ran beautifully, as before.
Now I have a potential intermittent fault as I could find no reasonable fault. (hopefully its ok tho- fingers crossed!)
Im going to put it on the inflatable and take it a run round the harbour for a while to see how it goes this weekend.
Click to expand...

Lets hope you have fixed it. If there were any deposits on the points that may have been the trouble They always advise that points should be scrupulously clean.. not so much as a finger print on them!
 
Well, heres hoping......
I actually quite like the engine. It gives a surprising amount of power for a supposed 5hp. It planes the dinghy easily with 2 on board, so aint that bad, AND its a longshaft!
And it only cost me £20.....!!!
Cheers
 
Don't know if this will help.

Many years ago our car wouldn't start if it was cold, couldn't find anything wrong nor could the garage.

To cut a long story short, the coil was open cct only when cold, was all okay after fitting a new coil.
 
Hi!
I have this model of motor. I used It last year - it was 07 of Jan. It works fine.
Now I want to change Stop knob on to Stop knob with safety lanyard.
Somebody done it?
 
Just buy a stop knob and its a direct easy change over. To stop the engine, the wire from the button is shorted to the engine case (earth). You shouldnt have any problems. I have run this engine a few times now, and its a great runner, with loads of power. It is very noisy though, and sounds like an aircraft taking off!! Thats the price you pay for it being air-cooled I suppose. Good luck.
 
Thank you. I know how it will be. When I asked about it I want to know who do something with standart OE complectation.
Next step what I want to do - it make coil lighting. OE part to order - now it is impossible and costs of it was 62 euro($80) and yamaha is not produce it :eek: I want to make myself during the winter. So I want to try to do it from coil from chinese moped. This year I done it with my Yamaha YBR-125: one of coils from generator didn't work - was with destroyed isolations. New OE costs 95 eur( $123) - I didn't want to buy it - because it is not cheap. So I removed it from engine and done myself. Time for this - 2 hour and $5 cost of materials - cord from cooper in isolation and special varnish:) Now I have all in parameters like in OE ;)
 
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