1989 Force 50 spark plugs

[Squeakit]

I have a 1989B model Force 50 that calls for L76V gapless spark plugs. Motor runs fine most of the time, but has a tendency to load up and foul plugs after a period of slow running. After searching the forums here, I decided to try a pair of QL77JC4 regular type plugs based on what I read, but I also read a bunch of stuff about gapless plugs and that they prevent preignition (detonation) and I am paranoid about running regular style plugs in this engine if they might burn it up. Can anybody reassure me that it is OK to run these plugs in this engine? Would rather pull the plugs and clean them off than have to replace a piston or two. Advice from Force experts would be much appreciated.

 

[12Footer]

Re: 1989 Force 50 spark plugs

I very strongly advise you to stick with the recommended gapless plugs on your motor.<br />Changing to a higher or lower heat range can cause major failures.<br /><br />If you are having a problem with fouling after prolonged idling, the problem is carbon. These motors are very dirty runners, requiring frequent decarb treatments when they are operated at low speed all the time.<br /><br />I've tried the additive type on both my 50HPs and they really run terrible. I've had much better results using the spray type decarb treatments like ValvTect. At 8 buks a can, it isn;t exactly cheap. But a can will last two or three treatments on the little 50HP.<br />I run in predominantly manatee zones, so it's idle everywhere (or 70% of the time).<br />But according to the operator's manual that came with the motor, the plugs are only good for 80 hours max, under "normal operating conditions"...Running idle speed all over the place is abnormal, so the plugs shouldn't last nearly as long.<br />I changed mine twice last year.

 

[Squeakit]

Re: 1989 Force 50 spark plugs

Thanks for the reply 12footer. I am going to take your advice and stick with the gapless plugs and try decarbing the engine. I am fortunate enough down here on this lake to be able to run WOT most of the time which my engine seems to prefer. I'd hate to have to run it slow as much as you do, but there are no manatees here on the Colorado River - too bad - it would be interesting to see one. Anyway, I'm glad I checked this out before installing these plugs. Thanks again.

 

[sony2001]

Re: 1989 Force 50 spark plugs

Keep your old set of plugs for when you do a decarbonnizing.