Super Jet What would cause this piston wash?

[Daralekt]

Could this be caused by anything besides a bad o ring? I inspected the o-ring, and didn't find any major damage. I also pulled the stator cover, and it was dry.

 

[D-Roc]

maybe you need to stagger jet from front to back? Its not un common to get different piston wash and plug readings from front to back on dual carbs and single carbs. the front is rich the back looks good.

 

[Dustin Mustangs]

Might be a reed issue. I had wash like that once due to a loose cage. It would also mist fuel up and out of the carbs when you revved it but that was hard to see unless the f/a was off.

 

[2XLR8]

It looks too much of a diff to be jetting .

 

[kevbo]

The back cyl has higher combustion temps. My single carb 701 got like that after a lot of full throttle riding. The rear plug was also lighter in color indicating higher temps. Easy to fix with dual carbs.

 

[Daralekt]

There was condensation in the forward cylinder. Water was entering the cylinder. I just don't know where yet. I'm going to replace the o rings and cross my fingers. The carbs are jetted properly, and have run flawlessly in the past.

 

[kevbo]

You need to equalize the temps, open the top screw 1/4 turn on the rear carb. Condensation? Do you do a lengthy blowout before heading home? Get the head and pipe up to 180 on the trailer, it takes a lot more dry revviing than Ive seen anyone do.

 

[donteatdirt]

I have the same problem with my piston wash in my 701 sn. Running a single 44mm with 115 in the low 135 in the main, pop-off is 24 psi. The ski has a milled head for 180 compression, which is dead even in both cylinders. Also, I made the stock flame arrestor breather easier by removing two of the screens. Any ideas?

 

[Waternut]

My guess is a blown o-ring. A tiny bit of water will steam clean that piston really well without bogging it down. I ran 2 jets too big on one of my cylinders before finally finding the right combination and it didn't look that clean. What kind of head are you running?

 

[Daralekt]

I bought a new set of o-rings. Just need to put the head back on, and find a place to ride.

 

[WaveDemon]

who ever thought the front cylinder was too rich needs to take a step back and think a little more. that is clearly water entering the cylinder. It looks steam cleaned.

 

[kevbo]

How could water get in without the compression and combustion gasses getting out? A cold piston will stay like new clean for a long time with TCW-3 oil.

 

[WaveDemon]

How could water get in without the compression and combustion gasses getting out? A cold piston will stay like new clean for a long time with TCW-3 oil.

what does that have to do with anything. if you have a bad oring, dome, or dropped sleeve water will get in the cylinder maybe at low rpm or when the motor is not running IDK. It happens.

 

[Matt_E]

How could water get in without the compression and combustion gasses getting out?

Blown o-ring.

 

[D-Roc]

too much fuel washes off the carbon. a blown o-ring is obvious, the pisser will sputte smoke. i have blown many o-rings and it never cleaned the piston off in the short time i ran it. just my experience.

 

[Matt_E]

I've had it happen a couple of times. It never sputtered on the pisser, either.
Stupid old Riva head.

Fuel is more likely though.

 

[WFO Speedracer]

Only the jet ski gods know for sure, consult them by rubbing on the magic B-pipe and let us know if they answer your query.

 

[Kawastyler]

Is the engine strong ported??? In past i had the same situation........... Little bubble in the cast from water to transferport.

Andy

 

[D-Roc]

wavedemon is correct about thinking it is rich and leaning it out. This should only be done if you know for sure the oring is not leaking water. It very well may get steamed cleaned if ran for long enough. i notice a bit of performance loss but mostly the sound sputtering from the head pisser. depending on cooling setup this may not happen. on mine it does and i head to shore. i think if lost spark and incomplete burning of fuel would do this, but i figure you would notice the dropping of 1 cylinder for sure and know something is up. What can happen to a carb to make it go rich besides the reeds defecting?

 

[Freakrider]

Augustaf recently posted something interesting that you can get water in a cylinder from a bad sealing surface at the exhaust manifold due to corrosion and that he's had this happen to him before.