Basic maintenance for aftermarket motors

[danielpak_ek9]

Waddap X. So normally I never really make posts I usually just always Google for any questions I got but the jetski scene isn't that big to have all the info online. Especially in regards to billet motors and the flat water scene. And everyone always just gives their opinions and it's hard to discern what's right. Question is, how often do you guys rebuild/service your motors? Who gets them rebuilt? Do you guys rebuild them because they actually need to or just preventative work to cause less damage? I got a new motor xs900 stock stroke and put on about 12 hours on it. Runs like a beast without issues, just wondering what preventative maintenance could I be doing to keep this motor in top notch condition. I run klotz 40:1 as well.

 

[Big Kahuna]

The Smaller the motor, the longer you need between rebuilt service (Assuming moderate wear and no water ingestion.)
Larger the Motor and or Rod Lengh the shorter between build.

Have a friend who tears down and inspects his cranks probably about every 15-20 hours........ He has saved a few motors from grenading by doing so. As in there would be bearings about to come loose, piston skirts cracked. etc etc

 

[Ryan Declark]

The Smaller the motor, the longer you need between rebuilt service (Assuming moderate wear and no water ingestion.)
Larger the Motor and or Rod Lengh the shorter between build.

Have a friend who tears down and inspects his cranks probably about every 15-20 hours........ He has saved a few motors from grenading by doing so. As in there would be bearings about to come loose, piston skirts cracked. etc etc

this makes me feel like my fiancé will be having a raised eyebrow even more than then she does now. but it makes sense. extremely smart. if i can get like 20 to 30 hrs on it before i break it down id be stoked. probably more then i would put on it in a season.

 

[Myself]

On a proper built engine with proper clearances and quality parts..........I see NO REASON to tear down at least until 50 hours or so. Measure clearances and then decide whether to go another 50 or so. The builder can tell you what the inspection interval should be. For example.......my buddy runs a VERY competitive pulling truck in the modified 2wd class. He runs a 525 (or something like that) stroked, tall deck, big block Chevy, and turns it about 8000 RPM's!!! He usually makes it through the whole season without a teardown. His builder really knows his stuff. Keep an eye on spark plugs and test compression regularly.........otherwise let 'er RIP!!!!!

 

[kevbo]

On any two stroke there are two main aspects that govern engine life. One is the width of the exhaust port and the other is operating rpm. A race winning cylinder turning 7800rpm will need pistons every dozen hours or so. The same cylinder with a slightly narrower port turning 7200rpm can last 200-300 hours. Other than that, wires, hoses, couplers, and anything that touches the engine will chafe horribly. So keep an eye on all that stuff.

 

[Big Kahuna]

On a proper built engine with proper clearances and quality parts..........I see NO REASON to tear down at least until 50 hours or so. Measure clearances and then decide whether to go another 50 or so. The builder can tell you what the inspection interval should be. For example.......my buddy runs a VERY competitive pulling truck in the modified 2wd class. He runs a 525 (or something like that) stroked, tall deck, big block Chevy, and turns it about 8000 RPM's!!! He usually makes it through the whole season without a teardown. His builder really knows his stuff. Keep an eye on spark plugs and test compression regularly.........otherwise let 'er RIP!!!!!

When you toss in 16+mm rods, the maintenance schedule changes exponentially...

 

[kevbo]

When you toss in 16+mm rods, the maintenance schedule changes exponentially...

It would be nice to have better data on the really large engines. I think riders aren't keeping good notes and are also not wanting to talk about failures. Big engines turning 7000rpm are stressed like Mod class 550s, except they vibrate a lot more! All the 68mm stock stroke stuff should be relatively easy to maintain as long as the porting and tuning are not too extreme.

 

[DylanS]

Unfortunately with freestyle engines most if not all of them will see water ingestion to some degree and it will shorten the life span of your parts significantly over time depending on the severity.
Stock stroke engines are pretty tough and personally dependent on the value of the top end that’s attached to it I’ll check the bottom end every 40-50 hours. In a perfect world with no water ingestion I’d replace my stock stroke crank at 100 hours anyways because they’re not super expensive.
If you have a o ring head it’s real easy to pop it off every now and then and check the condition of your cylinder walls which is usually a decent indication of how the rest of the engine is holding up.
once I pulled a 16mil dasa out of a lake after it sat for 2 years and spun the bearings out in diesel and it ran for an entire season before it let go. Had it rebuilt and blew the thrust washers out in one ride. Both instances were from water ingestion.
XS could probably give you a conservative number on when you should be checking out their engines too.

 

[fastgtfairlane]

I run a heavier oil mixture than most which is about 34:1. I also try to fog the engine after every use to try to eliminate moisture build up in the engine. Other than checking compression yearly and doing a leakdown, not much to do other than teardown for inspection. I dont have a large billet cylinder engine with a stroker crank but I do pit lots of hours on my engines. My lpw 735 is on its 5th straight season. Compression last I checked was the same as it was when I first broke it in.

 

[Baja 252]

On our 1200 Dasa we go by gallons of fuel used. At 50 gallons, the compression and engine internals looked great at our first refresh. Next time we pushed it to 75 gallons, compression was still 100% but all the bearings showed more wear. But I wouldn’t say they were in dangerous territory.
I wont push it to 100 gallons. I think that’s too much. For how we use it, 70 to 75 gallons is about right for us.
Water ingestion is a huge factor, it washes oil off the internal surfaces and shortens engine life dramatically.