Spark gap

[Tarzan13]

I have a 1990 48hp Johnson and bought some NGK BPZHS-10 spark plugs
What would be the best gap?
I run 50/1 and average 15kmh
Thanks

 

[Tarzan13]

I have a 1990 48hp Johnson and bought some NGK BPZHS-10 spark plugs
What would be the best gap?
I run 50/1 and average 15kmh
Thanks

Got them at .040 but seen on internet some use .030

 

[flyingscott]

Those motors tend to prefer champion plugs and those are gapped at .030

 

[Tarzan13]

Those motors tend to prefer champion plugs and those are gapped at .030

Should I gap the ngk at 30?

 

[oldboat1]

.040 should be correct. Test the strength of your magneto, though, using an adjustable spark tester available in auto parts stores. If the magneto is on the weak side (eg. if the spark is not sharp with an audible snap), you may want to try a plug gap somewhere between .030 and .040.

 

[Vic.S]

Should I gap the ngk at 30?

The recommended plugs are Champion QL78YC gapped at 0.030"

There is no exact NGK equivalent but the nearest will be BPZ8HS-10
The number you quote (BPZHS-10) does not make sense . . . you have left out the heat rating number

If you must use NGK plugs use ones with a 'Z' in the number because they are the equivalent of inductively suppressed Champion Q series plugs. Dont use resistor suppressed plugs ( with an 'R' in the number.)

the -10 in an NGK number indicates that they are supplied ready gapped at 1.0mm . . . you will have to close them down to 0.030" but you are unlikely to notice any difference between 0.030" and 0.040 "
At 0.030" they might last longer.. This I understand was the reason OMC reduced the recommended gap from 0.040" to 0.030" across the board in the late 1980s

 

[racerone]

Well-----0.030" ----0.035"----0.040" ---You won't notice the difference.