Help needed with sb 318

Try these no harm no foul plugs
RC12lyc
RN13LYC
RFN14LY
these extended tip plugs really do not mis they were developed as missing hurts emissions
these are 3/4 reach gasketed plugs- if you have tapered seats post back
If motor is run hard use the 12 if run a little at a time run the 14
these are inexpensive Champions
let's see the old plugs
and run a compression check while the plugs are out