davewill
New Member
I have a 1987 Johnson 4hp 2 stroke outboard model number BJ4BRCUD does any one know what the gap should be in the spark plugs & points. Thanks, Dave Williams.
Points & Plugs.
- Thread starter davewill
- Start date
Lakesailor
Well-Known Member
Champion QL77JC4 gapped at .030
It's important they are that plug, not an equivalent. There is a resistance built into that plug that helps the CD ignition to fire the correct voltage.
On that point. Are you sure it has points. It ought to be cd electronic ignition with those plugs fitted.
It's important they are that plug, not an equivalent. There is a resistance built into that plug that helps the CD ignition to fire the correct voltage.
On that point. Are you sure it has points. It ought to be cd electronic ignition with those plugs fitted.
davewill
New Member
Yes defiantly has 2 sets of points part number 0580148 I striped it down yesterday when I found it was only firing on 1 cylinder.
davewill
New Member
From the on line parts manual I have been looking at the plugs are RL86C or L86C.
VicS
Well-Known Member
The confusion arises because there were several variations of the 4 hp
Some have points and use RL86C or L86C
Others have CD ignition and use QL77JC4 or QL78V the latter being permanent gap plugs for contiuous high speed operation
For the points ignition I would not hestate to use NGK equivalents if they are easier to get (The Yanks love the Champions though)
(I use em on a 6hp with CD ignition as well)
Spark plugs
NGK spark plugs
Actually even more complex than that others with CD ignition used L77J4 or QL77J4
The Q stands for supressed
Some have points and use RL86C or L86C
Others have CD ignition and use QL77JC4 or QL78V the latter being permanent gap plugs for contiuous high speed operation
For the points ignition I would not hestate to use NGK equivalents if they are easier to get (The Yanks love the Champions though)
(I use em on a 6hp with CD ignition as well)
Spark plugs
NGK spark plugs
Actually even more complex than that others with CD ignition used L77J4 or QL77J4
The Q stands for supressed
Lakesailor
Well-Known Member
In that case try 0.020" gap. Everything I've seen for Johnsons recommends that. It's a starting point.
toad
Well-Known Member
Re: Points & Plugs.
As said plug gap 0.030" unless it is the deluxe model then 0.040" but I think that would be CD ignition. The points gap is set by opening or closing them until you get the timing marks to Aline but as you have to have the Johnson timing tool I would set them to 0.022" the same as the single Cly engines.
As said plug gap 0.030" unless it is the deluxe model then 0.040" but I think that would be CD ignition. The points gap is set by opening or closing them until you get the timing marks to Aline but as you have to have the Johnson timing tool I would set them to 0.022" the same as the single Cly engines.
Lakesailor
Well-Known Member
Re: Points & Plugs.
If you can see the cam through the flywheel apperture set them at the very top of the cam lobe.
That is just a starting point, as the dwell is set by timing the engine, still a roughly accurate gap will get you running and as you won't be after perfect tune on a 4hp you should be OK.
If you can see the cam through the flywheel apperture set them at the very top of the cam lobe.
That is just a starting point, as the dwell is set by timing the engine, still a roughly accurate gap will get you running and as you won't be after perfect tune on a 4hp you should be OK.