This melt down just might have me stumped..

gc4

I'd be lost without the x
I personally haven't had to deal with a problem like this, but this is a great thread full of useful information for if I ever do. Good luck with the ski!
 
Location
dfw
You don't think that variance is anything to worry about if it runs like it should..?
Pay attention when you start doing full throttle pulls. The plugs will be dark whenever you run below the pipe. Best acceleration will usually still be rich of peak rpm unless the pilot is very rich. That is why I don't like reverse jetting.
 
Location
dfw
Single Cylinder Chainsaw and Twin Cylinder at 82mm are different animals. That chainsaw is going to cool down faster. You are able to break it in faster. With your ski, you have alot of alum there which holds heat. That is why you need to let it cool longer.
A 50cc cylinder can dissipate the hottest combustion temps gasoline can make at 7000 rpm. A 300-400cc cylinder can barely get to best power temps without melting.
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Pay attention when you start doing full throttle pulls. The plugs will be dark whenever you run below the pipe. Best acceleration will usually still be rich of peak rpm unless the pilot is very rich. That is why I don't like reverse jetting.
Good info. I'm just confused on why my PTO side is so much darker than my mag side even though it's a signal carb and there isn't an air leak.
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Check your pulse line stuff. That's your front cylinder and a leak there would cause the front to be lean...
Line was fine but I replaced it with another new 3/16 tygon piece and new zip ties. Now after running for 20 minutes on new plugs and not going too hard on the throttle, occasional high speed with blips here and there, my plugs have no color at all. Ski is very rich on the bottom and definitely not excessively lean on the top.. I have it at 1 7/8 and I still feel like it's rich cuz it rides better at 1 1/2.

Tomorrow I'm going from a 95 to 80 gram spring and going up a size on the main and ride for a while. Then see what kind of color I'm getting.
 

DAG

Yes, my balls tickled from that landing
Location
Charlotte, NC
Does not explain the difference in plugs but keep an eye on that Tygon PVC tubing if you got it from McMaster. Its very soft and not rated for vacuum. I’ve had them pinch shut under throttle killing fuel delivery a few years ago. That’s one place I would defiantly recommend OEM or equivalent if you can get your hands on some.
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Does not explain the difference in plugs but keep an eye on that Tygon PVC tubing if you got it from McMaster. Its very soft and not rated for vacuum. I’ve had them pinch shut under throttle killing fuel delivery a few years ago. That’s one place I would defiantly recommend OEM or equivalent if you can get your hands on some.
Good to know!! This tygon is from the brand Oregon and we use it on everything at our small engine shop and I used it on my ski previously with new issues. . But I can see where it wouldn't be the best for the pulse line. I noticed a slight crease in my pulse line that I replaced, but I don't know if that made a difference.
 
Does not explain the difference in plugs but keep an eye on that Tygon PVC tubing if you got it from McMaster. Its very soft and not rated for vacuum. I’ve had them pinch shut under throttle killing fuel delivery a few years ago. That’s one place I would defiantly recommend OEM or equivalent if you can get your hands on some.
How did it pinch...? Bad routing?
I've used translucent fuel line for my pulse lines for years with no issue.
 

Roseand

The Weaponizer
Site Supporter
Location
Wisconsin
Yeah, I don't think you can judge my plug readings at all!! So I originally was at a 1.5 needle and seat with a 95 gram spring, and a 125 pilot and 150 main. Ski ran extremely good but stuck a piston.
Went to 127.5 pilot 2.0 n/s giving me 20 psi popoff with 95 g spring. Then a 152.5 main. Ski loaded up alot on the bottom sometimes but when it got on the pipe it ripped good at 2 turns out and I could have maybe went in a decent amount more but I wanted to play it safe.
Decided to put in a 115 popoff spring and a 155 main and ride it for a while. Rode it for over an hour with occasional short WOT runs(1-3 seconds). Plugs didn't show much color. Same as they do now. Ski was affected by mixture changes like it should.

So I went back to the 95 g spring, put in a 130 pilot and a 160 main! It definitely is rich in the bottom, and at 2.5 turns out on the top it was excessively rich. My ear is getting trained now too. At 1 3/4 it was still very rich, but then at 1 1/4 it was very nice above half throttle, and got better at 1 turn out and at 3/4 turns out I didn't notice much of a difference.
At 2.5 turns out I ran it WOT for 20 seconds and it was fine. Ran the 1 1/4 for 5 seconds too.
At 20 seconds of running rich WOT my plugs look the same as they do now, and I'm at 30 minutes run time at below 1.5 turns out on the high speed.
e7039b062e05bb150399f130c3e657c1.jpg


I can't get them dark but I can make the ski run excessively rich easily.. Idles great. Rear is darker still.
 
Top Bottom