A 1998 model 4hp Merc outboard runs on a 50:1 fuel to oil ratio. This works out to roughly one pint of 2cycle oil to six gallons of fuel.
A 4hp Mercury outboard requires a 50:1 fuel to 2 cycle oil mix.
one liter fuel 10 mill oil
0.020 in.
To find out how old a 4HP Mercury outboard is, you can look at the label on the transom bracket, where you will see a two digit number giving you the year it was built.
A ratio of 50:1 would be required, this is roughly one pint of 2 cycle oil, to six gallons of fuel.
If manufactured prior to 1965, a 24:1 ratio is required. Models 1966 and later use a 50:1 fuel to 2 cycle oil ratio.
Mine is a 2000 model and it has an NGK R BPR7HS10
BJ4BRE1A Is made in 1991 and the Fuel mix is 50 to 1
The points gap on a Merc 40 4hp is .020
You may have mistaken the '1' for a '2'..if your engine is a 4hp 2 cylinder it dates from 1978.
Johnson 4hp outboard bj4brcud
# connect fuel line # pump the primer bulb once and once only ! # move the throttle into the start position # ensure the gear is in neutral ( middle position ) # flick the carb switch open # Pull the pull start away to go