Please give me a PLUG read

Zero Client

Zero Client

BeerrroooOOOT!!!
Location
Douglasville, GA
Can someone give me a PLUG read? This is a 62t engine, Riva ported 62T cylinder bored to a 717 (701 +1mm). The ski is a 1994 WaveRadier. The pump is STOCK with the STOCK prop.

Carbs are STOCK dual 38s with chokes removed much like a RN Superjet. There on top sits aftermarket OceanPro Flame Arresters.

Engine has an ADA Aftermarket girdled head with 35cc domes.

Pro Tec exhaust pipe.

It also has a Riva/Advent CDI thats very old but similar in timing and spec as an MSD Enhancer.

The run was about 5 minutes of WOT, and 2 minutes of idle/mid throttle. The engine is only reaching 6500 RPMs on my tiny tach.

Am I too rich at WOT? F plug is FRONT.
 

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Zero Client

Zero Client

BeerrroooOOOT!!!
Location
Douglasville, GA
what, BPR8ES? cause they stick down a little more. Really I run either these or BR8ES. They don't make a diff.

You do understand that I cut the threads off for the read... Sorry I have to state that cause not many do this.
 
Ducky

Ducky

Back in the game!
Location
Charlotte, NC
Zero Client said:
what, BPR8ES? cause they stick down a little more. Really I run either these or BR8ES. They don't make a diff.

You do understand that I cut the threads off for the read... Sorry I have to state that cause not many do this.
Click to expand...

Ok yea, thats way above my knowledge level I guess. They just looked crazy to me. Hopefully someone smart will chime in.
 
Ducky

Ducky

Back in the game!
Location
Charlotte, NC
Ok I had to research this....pretty cool stuff I guess. Althought it seems like a pain in the ass. It looks like your front cylinder is running leaner than your rear cylinder.
 
Nuklear6

Nuklear6

I Dream 10' Surf!
Location
Bordentown, NJ by week / Brigantine, NJ by weekend
Does not look overly rich (it is a tad on the safe side). You may be able to lean on the top screw a bit (a hair more on the front then the back) but I'd only guess you'd gain a few 100 rpm at best once you have it dialed. Is been almost 10 years since I tuned a ski with a pro tech pipe so I could be wrong but I don't remember getting too much more rpm then you're getting now. Good pipe for mid range but don't think overrev was it's strong point. Please correct me if I'm wrong on the pipe.
 
Zero Client

Zero Client

BeerrroooOOOT!!!
Location
Douglasville, GA
Nuklear6 - Thank you.

You are the second person to tell me about Pro Tec pipes being best at the middle range and restrictive up top.

OK so now I'm running:

Dual 38mm Mikuni carbs
85l jets
.5 turn out on the low screws
115g spring
2.0ns
150 high jets
1.75 turns out on the high screws
​
The top post picture of the cut plugs are with the 150 jets. I had 140 high jets in there but the RPM was still the same - and the bottom porcelain smoke ring was just about as wide; however when I bumped to the 150 high jets it cleaned up, strengthened, and I now get better plug reads in the middle RPM. I gained a good power bump in the middle from 1/2 to 3/4 throttle. Next trip out I'll trim off the high screws and see what I can get above 3/4 throttle. Full throttle feels the same as 3/4 throttle.


Again for those of you who eye-ball plugs on the beach - you are doing it WRONG - but we all do it wrong really. Unless you have a x-ray vision it is impossible to see the bottom of the porcelain and measure it's smoke ring. A smoke ring should be brown and 1.5-2mm wide for a proper mixture. Any wider its too rich. Any less its too lean. This is the only way to be sure your long term WOT is tuned right. The best readings happen with new plugs with the threads cut OFF.

Now, with stand-ups we are not always going full WOT all the time so it is not always easy to get a good deep reading - which makes eye-balling on the beach an OK method for bottom end jumpers.
 
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