Spark Plug Question

So I go to change the spark plugs on my newly acquired project bike, a 1982 KZ750N1 spectre. The recommended plug is a NGK B8ES. The plugs that I removed are a B6ES which means a hotter plug.

Why would someone install a plug, 2 heat ranges hotter than recommended? To mask another problem?

Couple of WAG's: 1. Weak spark 2. Worn rings or valves causing excessive blowby/oil on plugs.
What condition are the plugs?

While changing the sparkplugs, also replace the sparkplug caps and wiring. The caps usually screw into the wires, and on some models the ignition coils have a screw on cap with a ferrule the retains the sparkplug wire(s).

almarconi wrote:

So I go to change the spark plugs on my newly acquired project bike, a 1982 KZ750N1 spectre. The recommended plug is a NGK B8ES. The plugs that I removed are a B6ES which means a hotter plug.

Why would someone install a plug, 2 heat ranges hotter than recommended? To mask another problem?

Because the B6ES is the recommended plug in other kawis like the 750 twins and a better choice for city driving if you want to avoid fouling plugs. Colder plugs for highway driving is good, they foul in the city if you do a lot of short trips. Also, if the bike is running a shade rich, they may have gone to a hotter plug to keep he plugs clear of carbon.

almarconi wrote:

So I go to change the spark plugs on my newly acquired project bike, a 1982 KZ750N1 spectre. The recommended plug is a NGK B8ES. The plugs that I removed are a B6ES which means a hotter plug.

Why would someone install a plug, 2 heat ranges hotter than recommended? To mask another problem?

Am thinking most if not all FSM's recommend against ever going more than one heat range hotter, at least on the large fours, because risks burning hole in piston.

Good Luck!

Could be that the p. o. had them lying around and used them instead of taking the time to get the correct ones. Could also be that they were the closest thing to correct available when he changed them. Could have been given bogus advice from some yahoo who didn't know any better..
Possibilities abound. Put the correct ones in and ride it like you stole it. If all is well, just chalk it up to solar flares or global warming.