Used SJ discoveries - oil + scuffed piston

M

mn_reeds

Location
MN
Picked up my first superjet last week - a 96 RN. It had a stock head that was milled as it tested 180/179 on my gauge. It wouldn't start so after a bit of haggling ended up with a semi-risky but non-covid priced ski.

It had a b-pipe but the screws were frozen so I pulled the headpipe off to get to work on those. First thing I noticed was the oil in the bottom of the ex manifold - could that be from his quoted "winterization" or is it a red flag? I also noticed it was an early production b-pipe with only a 42mm opening so I'll open that up to 47mm soon enough.


ex_oil (Large).jpg

Next I pulled the ex manifold to clean that up and port as well. Below is a pic of the PTO piston - I tried to compare to other pictures I found but is that just some scuffing or is it heat damage from the color change?
pto_scuf (Large).jpg

Should I tear this all the way down now? If it passes a leakdown test could I just run it for the last 2 months of the year or is that asking for issues? Deciding which way to go next as I currently wait for some parts from Jetmaniac.
 
kevbo

kevbo

Location
dfw
Your ski sounds like it could use some work. I inspect and repair everything on every used ski that I actually ride. Most PWC owners have different priorities.
 
M

mn_reeds

Location
MN
Appreciate the responses - just curious if that piston damage is from water ingestion, lean jetting, or heat? Looks like a full tear down ahead.

Found a few other things that did not inspire confidence as I continued to dig in. The carbs still had the anti-tamper plugs on them and original jets (130M, 70P) even though it had a b-pipe. Assuming the only way this was still feasible was due to stock airbox and all 3 screens still in tact? Either way I drilled out the plugs, disassembled and am about to dunk them in the ultrasonic.

On the good news side the ebox itself was in ok shape but I still tore that all down, cleaned it up, and re-assembled. Even better was being able to free all 3 b-pipe water screws thanks to reading some old threads on LOTS of heat. Ported both the exhaust manifold and headpipe to the new gasket and flat sanded all mating surfaces.


42mm to 47mm is a huge difference. A little finishing blending left but pretty close.
b-pipe (Large).jpg

While I was working on that I pulled and drilled the fittings out to 17/64".
fittings (Large).jpg

More teardown pictures to come.
 
kevbo

kevbo

Location
dfw
As usual, the previous owner knew how to turn a wrench and burn a piston. It may be okay though as long as the rings aren't stuck in the lands.. Slide the engine forward and spin the pump, it should be smooth and quiet and have some seal drag. If its been out for an impeller change pull the whole thing and clean/lube the splines. Also make sure the shaft tunnel is spotless before reassembly.
 
M

mn_reeds

Location
MN
@ kevbo - rings are not stuck and the ski does have even compression. Per Quinc can I just re-assemble and send it until the end of the season? Going to check with my local machinist to see how quick of a turnaround I could get.

Question on the carbs - did the 96's have anti-tamper caps? I read something about a carb change in 2004 but couldn't find specifics. The reason for asking is that my t-adjusters from jetmaniac are way too short due to the extended flange. Am I supposed to cut that off or do I need the longer screw (meaning these are not original carbs on the ski?)

carb_adjuster (Large).jpg

Also looks like I'm pulling the mid-shaft as I've got a good 10mm of gap here with the engine all the way back. Either missing the coupler washer or it needs to be pressed back to 20mm. Based on what I've found so far it will be both.

coupler (Large).jpg
 
Jhucke

Jhucke

Location
Wisconsin
How bad really is that scuffing on the piston? I mean seriously, these things ingest SO much water, it does not take long for a piston to look like that. Gouges are a different story because you likely ate something metal if thats the case. I agree with above^ fix the obvious and if it has power and tuned well, run it. It is good to be meticulous but try not to make yourself jump at shadows.
 
M

mn_reeds

Location
MN
Normally if I'm tearing into an engine it was from some sort of compression loss or failure. Since I didn't have any history with the ski I was assuming it might be worse than what it is. The local shop is at least a couple weeks out so as long as it passes a leakdown I'm going to re-assemble and run it. Then over the winter I'll tear it down, port it, and get it all ready for next year. Thanks for all of the comments and weighing in.

Still need a few more parts so I got to work on the carbs. I've searched a ton and don't think I've seen any threads or pictures related to cutting down the needle adjustment tubes. You could clearly see a casting mark on where they should be cutoff but it's not the easiest to get to. On my first attempt I tried to gradually increase drill bit sizes but had to go from 1/2" to 3/4" and that didn't end well. I got that all cleaned up with the die grinder but looked for something else (a mill would have been ideal)

In the bottom drawer I ran across my air reciprocating saw. I've never found a great use for this on a regular basis but it really was the ticket here. With the short 3/8" throw it was easy to maneuver and made quick work of them in no time.

Leftovers from both the high and low screws in front:
carb (Large).jpg


I'm sure there must have been an alternate route here but figured I'd post in case anyone else likes to do things the hard way too.
 
M

mn_reeds

Location
MN
Thanks @tomski - that would have been much easier.

Thought I would update this in case anyone stumbles on this thread and is scratching their head. It turns out that while the hull is '96 the motor is actually from a 2004 ski. Which is the first year they changed the OEM carbs to have the anti-taper caps and needed longer adjusters. When I was pulling the engine I found a 06/04 date on the ebox which made everything click into place.
 
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