1999 250 yamaha ox66 spark plugs, plug boot

[finaddict]

i have been using NGK BR9HS10 on my 250 the dealer says to use the HS9 has anyone done this?
Also i want to change the spark plug boots, i have never changed them I am the original owner and the boat is running fine but just thought that it would be a good maintenace, Has anyone done this procedure i have the type that screw on to the wire.

[rodbolt17]

BR9HS-10 is the correct plug, the numbers are changing but its the same plug.
the caps have resistors which can occasionaly fail.
why change them if they are ok?

[finaddict]

Thanks, i thought so. the reason for changuing the boots is they told me with time the continuity going thru is not the same as when the boots are new. I just finished putting new LP pumps in it and cleaning the oxygen sensor so i wanted to continue to tune it up.

[rodbolt17]

then simply unscrew the boots, test the continuity.
if in spec screw them back on.
did you actually TEST the O2 sensor output voltage AFTER cleaning?
the flame test is a teat on a boar hog.
faulty O2 sensor feed back can and will damage a piston.

[finaddict]

No i did not, Just put it back in and started it up at first i heard a loud bang then it started idling high about 200 rpm more then usual out of water. then took it our for a sea trial and then idle back to normal. Should i test it if so where can i get the process. Thanks for ur reply

[rodbolt17]

proper testing of output voltage is VERY important after ANY maint action.
otherwise, why do it?
why clean an O2 sensor if your not going to check its output AFTER cleaning?
there are NO codes associated with the O2 sensor on the OX66 motors, even if you unplug it.
yet it can pop a piston.