EGT gauge no more burnt pistons.

[snikwad003]

I like the idea of extracting every thing its got and Ive felt a kx125 and kx250 run its best while melting down a few times, not fun but sometimes you just have to push it over the edge cause some dude on a 450 valve clacker wanted to drag race in the parking lot. You going to get one of those scan tools so you can adjust timing? You gonna monitor any thing else?
Is your 18/8db gas resistant?

 

[BoLongo]

I haven't looked into timing adjustment but from I what I've heard it sounds expensive.

My next thing will be an electric trim tab between the pumps and after that, electric brakes on the trailer. If I don't seize another engine, I'll get to do some cosmetic work and reupholster my seats. :coolgleam:

 

[IDoSeaDoo]

I had egt sensors on my challenger back when it was 2 stroke, and routinely saw Temps above 1100. Couldn't get them to go lower. It ran good and plugs looked good but it still ran hot and eventually the motor died. Forgot the reason of the last failure, but here's what I found. When I was gutting the boat for the conversion, I found a little piece of shell in that cooling line fitting on the water box. It was the fitting that attaches to the rear coolant line that attaches to the T at the back of the engine. God knows how long that's been clogged, but you had to remove the whole water box to notice that. I went though 3 motors on that boat that all failed for unexplained reasons. Two top ends and one crank. Then I found out that the cooling system was not working correctly.
I had the exact same thing with the exact same results on my 787 spx. On the last rebuild, I found that that same cooling line was clogged solid with sand. I've cleared out that line and rebuilt the motor and 28 hours into it. So far so good. Check that line on both motors, and install water strainers.

 

[BoLongo]

I have been down many rabbit holes that ended up being something so simple as a shell in a cooling line.

Now you got me thinking. I used to love the cooling system pisser on my skis that told me when the cooling system was working. My Kawi had the pisser up front, once I blew a head gasket and steam was coming out instead of water. I stopped the engine; that pisser saved that engine.

Seadoo hid the pissers on the back of the boat which makes it useless, and you have no way of knowing if both engines are working because they are coming out the same outlet.


I am going to reroute my pissers one for each engine closer to the driver’s seat. That way I will be able to see if the cooling systems are working for each engine

 

[IDoSeaDoo]

That's just it, the pisser never stopped working. The engine just always ran hotter than it was supposed to. I tell everyone to watch that hose, it goes into the exhaust and if blocked it's a silent killer.

 

[IDoSeaDoo]

But you're right, relocating that is a good idea [emoji106]

 

[snikwad003]

I put those same pissers in the side of mine but the 45 degree ones. Either the distance or the bigger line I had to use it only squirts with some throttle. I put mine closer to the back than you have marked but you could reach it from the speaker hole to put the nuts on the back

 

[IDoSeaDoo]

My skis are the same way, only squirt with a bit of throttle, but seem to run okay

 

[BoLongo]

Josh, I like your thinking with your pissers. I figured I would move my pissers a little closer to the drivers seat, so I put my hand on them. :facepalmjust kidding).

IDoSeaDoo, do you recommend pulling the inlet hose at the head and back-flushing with a garden hose once or twice during the season?

 

[IDoSeaDoo]

If you can reach it. My hands are too big to get in there. I put a break in a convenient access point in mine, connected with a straight plastic connector. This makes it more convenient for a ski as I'd have to remove the battery to get it off the exhaust fitting, and I can blow air through the fitting itself. It's super hard to get to that T joint behind the motor, so I never even tired doing it that way. No room with the exhaust so close.

 

[BoLongo]

Help me understand which hose you are talking about.

 

[BoLongo]

I think you are talking about the Jug Drains. I am sure Rotax was counting on a certain amount of water to flow through the drains to help transfer heat from the engine. So if they are clogged, it could affect the efficiency of the cooling system. Another poor design where they allow large objects to enter the cooling system but the drain outlet is smaller than the inlet which could result in clogging.

 

[IDoSeaDoo]

Yes, it is the jug drains. It's the lowest point of the motor, from which the water drains to the exhaust. It doesn't have to be anything very large to clog it up. My SPX had just a solid plug of sand/mud in it. It settles there over time and builds up because I don't think the flow through that hose is that fast. Mud can get pretty hard once it dries out too. Being on the bottom of the hull, the hose is the low point and things tend to collect there. My Challenger had a small piece of shell stuck right in the water box fitting. It made its way through the whole system and got stuck right at the very last part of the last fitting. :facepalm:

 

[snikwad003]

Here is a foto for refrence of the 45 degree version of the pissers you have posted up there

The straight ones you have pictured would probably easyer to see but these are easy enough to see with a quick look :cheers:

 

[BoLongo]

My boat hates me:banghead:. I was all set to take the family out for a day on the lake after church. Started up the starboard engine; it sounded like I spun a bearing on the crank; I was devastated.

I pulled the pump; it turned out to be a pump bearing. The bearings looked good when I bought the boat; in fact, they still look good they just sound like hell.

I'm just not feeling the love from my family or this boat!

I bought these pissers.


Josh, your boat looks great pissing on the lake . I'm jealous

 

[IDoSeaDoo]

I happened across the post where you had the bracket extension for the fuel pump... is that attached to just two MAG cover bolts? That may not be enough to hold that big of a lever while it's vibrating. I wouldn't want that to damage your mag housing. I had an RV cover crack because I was using aftermarket flame arrestors without the bracket that secures them to the head. That crack created a small lean condition that I hunted for weeks.

Anyway, any updates? Did you get to test it/dial in your carbs? Do the plug readings correspond accordingly?

 

[snikwad003]

You get your machine shop ordeal figured out?

 

[BoLongo]

I finally got out on the water today, but I only had an hour. The motors ran well for the first ten minutes. I stopped and let them cool down. When I restarted, the starboard engine (problem child) started backfiring slightly. I pulled the choke for a bit, and it ran great back to the boat ramp. I checked the rectifiers and both engines will raise the voltage to 13.5 volts. I pulled the carbs and checked the rotary valve timing it is perfect. I'm now going to pull the mag cover to see if I can see any issues with the pickup.

I am also building a time machine, so I can go back in time to tell myself not to buy this boat.

 

[IDoSeaDoo]

Yea, i too had infinite issues with the 787, enough so that i took the time and pain to convert my challenger to 4tec.

 

[snikwad003]

Ahhhha... the game of high output engines. I love it. I wonder if you have a hidden carb problem.

 

[IDoSeaDoo]

Have you pressure tested the motor? I had the tiniest crack in my rotary valve cover that i would have never found had i not ptested it. It was from not using the carb stabilizer bracket when i had aftermarket flame arrestors.

 

[BoLongo]

I have switched carbs between engines, so I have ruled out carbs; I am pretty sure it is electrical. Not my favorite system to work on.

I did a pressure test on the motors when I bench built them, but I have had the top-end off a couple of times while on the boat. I did use Permatex High Tack on the rotary valve cover when I put it back on today. I was already using High Tack on the carburetor base gaskets.

 

[ialonso]

I have switched carbs between engines, so I have ruled out carbs; I am pretty sure it is electrical. Not my favorite system to work on.

I did a pressure test on the motors when I bench built them, but I have had the top-end off a couple of times while on the boat. I did use Permatex High Tack on the rotary valve cover when I put it back on today. I was already using High Tack on the carburetor base gaskets.

The nice thing is that the electric part (If it affects one cylinder only,as it appears) should not be horrible to troubleshoot.

These engines fire on every half turn, so both plugs fire every time.

The spark plug caps are screwed in, and where they meet the cable have this screw piece inside that has rusted off once for me, and I had to replace the cap. If it still screws and unscrews in, you can cut a small amount of spark plug cable and re-screw the cap on to see if that solves the issue. If not... I would swap the spark plug cable back to front if the cable reaches. You can swap the coils between motors to see if the issue follows the the coil too.

Best of Luck!

 

[BoLongo]

Thank You, ialonso.

I did cut the caps and checked the screws. I was having an issue with the PTO Cylinder, but now I'm not sure which cylinder is backfiring. I almost have the MAG cover off; a nightmare while in the boat. Hope to find some answers.

 

[IDoSeaDoo]

I had the spark plug cables go out on my 787 spx. All that vibration wore out the insulation. I've become a lot better about securing my wires and hoses as i became a better mechanic. But the way i realized my wires were bad was that touching something in the open electrical box while cranking shocked me. Another, perhaps more reliable way would be to buy one of those spark testers, where you can adjust the gap. I widened the gap to like 1cm and watch it arc across every time, steadily without missing now that i replaced the plug wires. Got a length of 7mm cooper core off ebay. Detaching and reattaching to the coil was tricky, as that plastic restraint piece is super delicate. Indeed, i broke mine. And am not sure how long it's going to hold. But right now, the spark is strong and identical on both cylinders