the br is a resistor type plug the b is regular same heat range and everything should use br whenever possible and a must for electronic ignition
RD350 Spark plug gap & Plug spec. 0.022 to 0.025" NGK B8HS
you have to make ngk b8hs-10
Please consult your dealer for this information that way you know it is correctHere is what I could findSUZUKI MARINE ENGINES Spark PlugsEngine......Model......Year......Standard Plug.........Premium Plug 2-cyl..........DT40......82-80.....NGK4322 (BR8HS)...NGK7001 (Iridium BR8HIX)2-cyl..........DT40c.....92-84....NGK5510 (B8HS)......NGK7001 (Iridium BR8HIX)2-cyl..........PU40......93..........NGK4322 (BR8HS).....NGK7001 (Iridium BR8HIX)3-cyl..........DT65......92-85.....NGK5510 (B8HS).......NGK7001 (Iridium BR8HIX)3-cyl..........DT75......96-93.....NGK4322 (BR8HS).....NGK7001 (Iridium BR8HIX)3-cyl..........DT85......93..........NGK4322 (BR8HS).....NGK7001 (Iridium BR8HIX)3-cyl..........PU55......93-89.....NGK5510 (B8HS).......NGK7001 (Iridium BR8HIX)3-cyl..........PU85......93-89.....NGK5510 (B8HS).......NGK7001 (Iridium BR8HIX)4-cyl..........DT115....00-98.....NGK4322 (BR8HS).....NGK7001 (Iridium BR8HIX)4-cyl..........DT115....90-81.....NGK5510 (B8HS).......NGK7001 (Iridium BR8HIX)4-cyl.4-Stroke....DF115....04-01.....N/A..........................NGK6418 (Iridium BKR6EIX)4-cyl.4-Stroke....DF115....04-01....NGK7092 (BKR6EGP)..N/A4-cyl.4-Stroke....DF60......04-98....NGK4008....................NGK6637 (Iridium BPR6EIX)4-cyl.4-Stroke....DF60......04-98....NGK7084....................N/A4-cyl.4-Stroke....DF70......04-98....NGK4008...................NGK6637 (Iridium BPR6EIX)4-cyl.4-Stroke....DF70......04-98....NGK7084...................N/AALL............DF4........04-03....NGK4008...................NGK6637 (Iridium BPR6EIX)ALL............DF4........04-03....NGK7084...................N/AALL............DF6........04-03....NGK4008...................NGK6637 (Iridium BPR6EIX)ALL............DF6........04-03....NGK7084...................N/AALL............DT4........87-85....NGK7331 (BP6HS).....NGK3419 (Iridium BR6HIX)V6.............DF225.....04.........N/A............................NGK6418 (Iridium BKR6EIX)V6.............DF225.....04.........NGK7092 (BKR6EGP)..N/AHope This Helps.
The 1986 model, DT75 Suzuki outboard requires an NGK B8HS plug, or equivalent, gapped to .034 in.
The Suzuki 115 hp uses an NGK B8HS plug, gapped to .035in.