1985 Force 85hp (856F5A) spark plug questions

[ToonTy]

I am looking to get the best performance out of my old Force 3 cylinder motor. I currently have Champion UL18V plugs in it and they seem to run fairly well. When I bought it the motor had NGK BUHW plugs in it. Yesterday I took it out and put the BUHW plugs back in it, but I could only get to 4K rpms at WOT. Pulled up to a beach and swapped out for the UL18V plugs and rps went back up to normal at WOT. The Clymer manual I have says that it should use Champion L20V or NGK BUH plugs, but I have seen posts on here sharing that people use several different plugs including NGK BUHX. When I pull up the motor on parts websites they almost all have the UL18V plug listed.

What are your thoughts? Should I try a different plug? Why would the BUHW cause the rpms to drop so much at WOT?

 

[jerryjerry05]

Sounds like one of the plugs might be bad??
Maybe change the end of the plug wire, and change the connectors on ALL
of the wires.

 

[ToonTy]

I thought that maybe one of the plugs may be bad. I will take a closer look at them later this week.

I changed all of the boots and connectors on the plug wires last season. They are all in great shape.

 

[ToonTy]

Going on a trip, but when I get back I am going to try the NGK 2522 BUHX plugs. I read in an old thread that someone said these alleviated an intermittent misfire at higher rpms. I too think that I hear this every once in a while.

 

[jerryjerry05]

When I say connectors I mean the wire ends on all the wires, stator and trigger too.

High speed miss: bad plug, loose trigger wire(under the shrink wrap), reeds.

 

[ToonTy]

Thanks Jerry! I will go back through all of the connections again to see if there is anything not making good contact.