Super Jet piston wash vs plug color

[mybad]

Looking for input on plug color and piston wash.
Im running a 701 Group K. Its ported, b pipe, oem head at 195 psi on 110 octane, lightened flywheel, 10/16 hooker, top loader, tbm rideplate, taper bored carbs, prok filters, #zero lightened flywheel, reed spacer, protec mod cdi and stuffers.
Motor and pipe temps are good. Ski runs good. Engine compartment seems dry. Has a slight occasional hesitation when running buoys when getting on gas.
The plugs are dark brown and a little oily with a very small spot of water discoloration on the electrode. The piston wash is a dark carbon from edge to edge. So the plugs indicate RICH.....but the piston wash indicates LEAN. Any suggestions or anyone else experience this?

 

[Half flip95]

im hardly qualified to be giving tuning advice but, the safe thing to do would be to fatten it up until it gets sluggish then work backwards from there

 

[Blue]

Due to the transfer angle being changed when a cylinder is ported. That will cause the wash pattern to be different as the fuel may be directed to the top of the cylinder and not across the dome of the piston which is how a stock cylinder flows. That will cause a black piston as the fuel no longer flows over the piston to clean it off. Remember if your trying to read plugs you need to run it at the rpm range ur testing then chop the throttle to get an accurate reading if u let it idle it will be a false reading.

 

[bsc702]

I have a similar set up on my ski and i was wondering the same thing, top of piston is black carbon end to end and plugs look perfect any more info would be great.

 

[mybad]

Thanks Blue. Very good information. I will rely on the plug reading then. Just put in a new set.

 

[Quinc]

Due to the transfer angle being changed when a cylinder is ported. That will cause the wash pattern to be different as the fuel may be directed to the top of the cylinder and not across the dome of the piston which is how a stock cylinder flows. That will cause a black piston as the fuel no longer flows over the piston to clean it off. Remember if your trying to read plugs you need to run it at the rpm range ur testing then chop the throttle to get an accurate reading if u let it idle it will be a false reading.

Good to know! I was wondering this same thing.

 

[waxhead]

If your doing your top end and all the rest is ok, then richen it up till you lose top end.
Put a tacho in it and wind the highs in until you get the best rpm. Then fatten it up 1/8 of a turn it will pull hard like that.
Thats just a basic way of doing it

 

[Blue]

Its actually easier to get a plug reading with a used set that already has some carbon. It makes it easier to read. New plugs take awhile to carbon up. I tell guys that are not real experianced to pin the ski to a seawall or post in 3ft of water and run it wot. Adjust it in or out on the highs till it peaks then back it out 1\8 turn to 1\4 to ensure u dont burn it up. This will take several trys of adjusting but it easier to hear how the motors reving without the hood. Once you think its close run it wot again chop the throttle after a few seconds and read the plugs. Adjust 1/8 of a turn if needed. Simple but it works for the average guy with minimal experiance.

 

[Superjet1000]

What's a good technique to use on a 10mm flat water ski which can't be ridden at wot long enough to get RPM readings.
Plugs look good but no piston wash.


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