1997 Force - spark plugs

[waterguy]

I recently purchased a 1997, 18' Stingray bowrider with a 75 HP Force outboard motor. The boats maximum speed with four adults in it is 40 MPH. I checked the sparkplugs in it and I don't think they were ever changed. It had Champion L76V plugs in it, and I would like to replace them with Champion L78V. Does anyone know if this would be all right, and would it increase the boats performance? The manufacture says the top speed of the boat wit h a force 75 HP should be 42 MPH. Any thoughts?........thanks

 

[12Footer]

Re: 1997 Force - spark plugs

Welcome to iboats,Waterguy <br />Stick with the QL76V plug. The 78V is hotter and can damage your engine. Your engine should be able to get better than 4800RPM at full throttle.If not, you may be overpropped,or have an engine problem.

 

[waterguy]

Re: 1997 Force - spark plugs

Thanks 12footer, You are right on the money. I spoke to a marine mechanic today and he said the same thing. "The L78Vs will fry the motor in time. Don't use them". He also checked the motor and said that the prop is what is causing the low RPMs. I could change it and increase the rpms, but he recommended that I use the one which came on the boat. He said that the manufactures give you a midrange prop so us new guys to boating don't over rev the motor. 40 MPH is plenty fast enough for me. It can pull two skiers and that's enough. Thanks you for your quick and accurate response......Waterguy

 

[12Footer]

Re: 1997 Force - spark plugs

My pleasure, Waterguy.Happy boating