How tough to rebuild 717 seadoo engine? 96 speedster

[uraceulose]

Pretty sure my lower end let loose today. Seized up.
I see rebuild kits online anywhere from 300-550. Complete rebuilt for $850-$1200 with core. It seems like a cracked rod or rod bearing. Looked in the pump and impeller is all clear but will disconnect pump to be sure. Driver side turns over by hand, pass side is frozen. It’s probably $1000-$1500 to have done in my local (3 hrs away) area

 

[POPPS]

Since it's a jet boat, your first move is to remove the hood, split the cases, and then proceed from there.

 

[H€PHÆ$TU$]

I'm new to boats but not new to mechanics in the least bit. I recently had to tear down four 720 engines to build one good engine. I have enough good parts to build another, which I will do eventually. But I was running out of time in the season and just wanted to get on the water so I bought an SBT engine for my second engine.

They're not hard to build, IMO. It's more of a cost analysis than anything. You can't rebuild cranks yourself. So if your crank isn't reusable, you need to exchange it. The gasket set is about $100, so you're into the $600-700 range right there before you even turn a wrench. An SBT engine with one year warranty is $800. Don't know about you, but a day of my time is worth more than that cost difference.

 

[uraceulose]

Thank you so much. This is what I was wondering. I'll look into SBT...

Was the timing setting and syncing the motors tough?

 

[H€PHÆ$TU$]

Timing the RV is easy. If you don't have a degree ring, get one with your motor. They're $12, just follow the shop manual. If you're super-cheap, you can even print and cut them them from PDF's available for free online. That's the least of the worries.

Not sure what you mean by syncing motors. There is an adjustment procedure in the shop manual to sync the throttle cables but I think that most agree that this is an exercise in futility and that the levers will never match up exactly. I messed with my cables for hours trying to get them to sync and every time I go out they're slightly different from where I thought I had them. I got them "close enough" and just live with it.

 

[H€PHÆ$TU$]

If your throttle cables are synced good enough for you now, don't remove them. Instead, remove the brackets from the carbs before you pull them. Then you shouldn't have to mess with syncing them again.

You really need to go through, or have a qualified tech go through, your carbs and fuel system before you run a new engine. The fuel system is the #1 reason engines fail and if there's something not right now, it will just destroy your new engine, too.

 

[uraceulose]

Thank you. I literally just spend $1200 on having the carbs all gone through, supposedly made sure oil pumps were functioning and did a power tune on the boat at the Ski Clinic. The boat was running perfectly and better than it has ever ran. I had it out for about an hour and a half and then poof, the one motor let go.

Has anyone had any experience with the SBT rebuilt motors? They're about the same price on ebay but I'd like to go with the one that has the best reviews.

I also have rebuilt the pumps, carbon seals, all new fuel lines, selector valves and filters.

I see what you mean on the syncing of the carbs and I'll just do it that way...leave the cables attached.

Looking at it, it seems pretty straightforward to pull the engine and replace unless I'm missing something. The timing is the only thing that has me a little worried.

 

[H€PHÆ$TU$]

If you're sure about your carbs then just take them off and leave them attached to the cables, set them aside. You need to evaluate your failure though. "Just had carbs rebuilt, hour later engine died," sounds fishy.

Here's SBT's step-by-step guide on how to do it. They're doing it on a ski but it's the same basic procedure:

https://www.shopsbt.com/pdfs/sd580650720.pdf

You really should own a shop manual though.

 

[uraceulose]

Thanks so much. I do have the shop manual as well and will contact the guys who just did the work on it cause it is definitely odd