Super Jet fouling plugs??

[Waternut]

I've been tuning my engine and have finally gotten it to give good clean response everywhere. However, when I changed the jets last, it ran ok and when I stopped to adjust the screws, one of the plugs fouled. No biggy...the plugs were old anyway. Put new plugs in and it ran great. I let a friend try out my ski and he was riding around at very low speed (just off idle) and after about a minute or two I could hear that the ski was running bad and he had fouled one of the plugs. If I ride like how it should be ridden, everything works fine... Is it normal to foul a plug if at low speed too long?

I'm running a speedwerx big bore motor with b pipe, MSD total loss, dual 44 GRS carbs, and 200psi ADA head.

 

[Tyler Zane]

yes, but can be kept to a minimal. i had a mx bike back in the day that would foul plugs like crazy, but was a bat out of hell if you gave it hell. my ski is set up by one of the best and ill foul a plug if i let a friend putt around on it for awhile.

 

[CARBONX2]

Plug gap?
Break in plug leads?

 

[Screwy]

yes, but can be kept to a minimal. i had a mx bike back in the day that would foul plugs like crazy, but was a bat out of hell if you gave it hell. my ski is set up by one of the best and ill foul a plug if i let a friend putt around on it for awhile.

i agree. i had a cr125 that was like that. you could beat it to death, just don't putt around on it. that all comes down to the premix ratio. thats why guys with bass boat can putt around all day then mash the gas when they wanna try some where new, their motors only inject as much oil as they need at a given throttle setting. guys who premix have a constant oil ratio at any given throttle setting (usually 50:1), when you putt around all the extra oil just sits in the lower crank case. then when you do snap the throttle open it all goes right up into the combustion chamber and oops there goes your plugs.

 

[5810]

when was ur last carb rebuild with (new parts), i bet its ur needle and seat, had that happen to couple of friends. even with couple month old ss 46 carbs

 

[Waternut]

I was thinking about rebuilding the carbs but didn't want to spend that money unnecessarily.

 

[D-Roc]

what plugs?

 

[Waternut]

Spark plugs...

 

[D-Roc]

haha, okay are they br8es? br8eg? what temp? resistor? non resistor?

 

[Waternut]

BR8ES...same thing I've used in every ski but this engine is fairly new to me.

 

[D-Roc]

the msd will fire wet fouled plugs and get a flooded engine running but sometimes it does foul out the plug so it is bad. i don't know why this happens but i have had it with my ski when i used two br9eg plugs, it ran really great and crisp but it fouled the plug so it ran like crap and i ditch them thinking it was the temp range. i tryed br8eg plugs and ran awesome and longer before they fouled up on warm up. i went back to the br8es and never fouled a plug so it ran like crap. you have msd caps on the wires?

 

[Waternut]

I do not have MSD boots or wires.

 

[D-Roc]

hmmmmmm, what wires and boots are you running? the wires should be radio interference protected and the msd caps do not have restrictors, the restrictor will be in your br8es plug then. I have just replaced my old msd wires with these "performance" Accel wires. i am waiting for my digital ignition Nology hot wires to come in so i can run silerstone non resistor plugs. getting the right plug and cap/wire is important.

 

[Waternut]

Well I rebuilt the carbs today with new kits from Superjet-113 and still fouled a plug. Even at a cruise speed, I'm fouling the rear plug. I want to say it's always been the rear plug. The spark is very strong but my plug wires are getting old...I'll try different wires tomorrow and see if that fixes it. I should've checked my needle and seat size when I had them apart just for reference. The rear cylinder is the slave carb so maybe that has something to do with this but I don't really see how.

 

[D-Roc]

the pto piston does a bit more work that the flywheel side and i know peeps that stagger jet their skis. i don't but my screws are adjusted a bit different from front to back. It could be a bad wire. i replaced my wires because they where getting old. i was not fouling plugs.

 

[Waternut]

Ok I just went out at dusk to get a better idea of what was going with the sparks and found something very interesting. Apparently the spark isn't firing across the gap even after I cleaned up the plug. It's firing at the base of the porcelain most of the time and every now and then it fires across the gap. I went up to get an older plug that I had laying around and it did the same thing even though I had never fouled that plug. The issue followed the plug and the not the wires. Is that just what a fouled plug does or is that something else entirely?

I took this video real quick with the cell phone just to show it sparking inside the plug and then every now then firing across the gap. The second half of the video did seem to fire normally but still very wierd.

 

[D-Roc]

that spark looks very yellow when it is fouling or missing or arcing . whatever you call it, i think that may be a fouled plug. it is hard to tell in the video but it does not look right. did you switch your wires around front to back or just the plug? i took a pic of my spark but was told that a picture of a spark means nothing but have a look. do you have any new plugs and will they just foul up again on your next ride?

 

[Waternut]

Yeah I know what the spark is supposed to look like. The plugs I have in there have been in the ski for a grand total of 20-30 minutes. I can go get some new plugs and maybe lean out the bottom end on the rear cylinder a quarter turn and see what happens. I didn't swap wires but I played musical plugs and both bad plugs do the same thing on either wire and the good plug fires good on both wires.

 

[D-Roc]

when mine fouled, the ski ran perfect and then bam, dropped a cylinder and limped to the dock. mine alway fouled if i didn't get the motor hot and then blasted the throttle. i never had this problem again when i used the br8es plugs.

 

[Tyler Zane]

i have never had a plug foul so bad in my ski that it had to limp back. it just had horrible throttle response like it was way to rich.