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'1991 GT 200 200hp possible problem/Reading plugs

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stratos976

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1991 Johnson GT 200 m/n VJ200SLEID s/n 02000222


I took the plugs out this evening to check and replace them. I noticed on the Port bank of cylinders, Bottom plug the color was quite different from the rest.

All ther other plugs had a tan color to the electrode and damp enough to be shiny, but not what I would call wet........ The plug in question, the electrode was dry looking and a charcoal gray color...not black carbon or deposits on it just a dark grey color.

Was this cylinder not getting fuel???? What else could cause this? I just ran it yesterday, fishing a tournament, had a little trouble starting it and noticed a stutter every now and then when idling, that was the reason for pulling the plugs , seemed to run ok on top though.​
 
Re: '91 GT 200 possible problem/Reading plugs

You must do a compression test !!-------------Then put a timing light on all 6 to verify spark to each cylinder.----------------You can look into the carburetor bores ( strong flashlight ) and compare fuel coming up the main jet / nozzle.---------------If you determine a fuel problem, stop untill it is fixed.---------If that cylinder was not getting fuel for a long time then also NO OIL !
 
Re: '91 GT 200 possible problem/Reading plugs

Or that cylinder is running real lean and therefore running real hot. As said above check the compression on all. Also check that the carbs (especially the lower one) are all clean and flowing nicely.
 
A 2 stroke engine has sealed crankcases ( your GT 200 has six of them ) at idle there is more time for air to leak.-------------That is why they usually run OK at full throttle.---------------Major internal engine problems show up first at idle speeds.-----These problems should be diagnosed and corrected !!!!----------If not you risk major repairs. ------Simple really.
 
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