97 SPX RAVE valve stem split off

[andy.262]

OK, so on my last ride just as I was approaching the launch, my engine started loudly rattling. I stopped the engine (I stopped it intentionally, it didn't stall) because obviously something was wrong.

Turns out, my RAVE valves had both broken apart. When I got in there, ALL of the plastic and rubber valve parts were completely covered in blackened oil, and I found that the valve had split. So now my questions are:
What should be my next move here?
I don't want to run it if there are pieces of valve in the engine, right?
Any chance I could just stick a shop vac over the valve opening and suck all the loose bits out? Is that a stupid idea?
What are some potential causes of this? Is it a symptom of something else being broken?


This was my first ride after replacing the fuel selector and rebuilding the carbs (with genuine Mikuni parts), but I'm guessing that that's probably unrelated.

 

[AKnarrowback]

Disconnect the battery first.

Remove the head of the motor to get any parts out and start inspecting the extent of the damage. Pulling the head is easy, just spin the bolts out.

Do this, send us pictures.

 

[andy.262]

OK, got the head off and scooped out the bits of RAVE valve that were in there. Looks like maybe the front piston can be saved, but the rear is all chewed up. I guess that means I can't just get new RAVEs and call it a day...

This is the front piston




And this is the rear

 

[AKnarrowback]

You need to do a complete take down of your motor and inspect the crank as well. This is not a simple top end rebuild. Sorry to say.

I would not expect visible damage in the crank area, but you are checking to see if any of the bearings are rough from any piston material falling down low. You need to clean out each bearing with brake clean and blow them out with compressed air, DO NOT let the bearing spin while doing this since it will be dry. After they are clean drop some injection oil into each race , roll things around to give all the races and balls (no snickering) a light layer of oil then gentle roll each bearing feeling for any roughness.

What year and model is this machine?

 

[andy.262]

Its a 97 SPX, 787

Would I have to take the engine out of the machine to do this, or can I do it in place? I'd rather not have to take it out and re-align it and all that.

 

[mikidymac]

It has to come out.

 

[andy.262]

So if I do this and nothing on the bottom end needs to be replaced, am I just looking at new RAVES and new pistons? Can I get away with only replacing the rear piston or do they need to be replaced as a set?

To be honest I'm not sure I'm prepared for this big of a job. Can a novice DIY'er pull this off?

 

[AKnarrowback]

How much of a hands on mechanic are you? If I told you to replace the intake manifold of your car/truck would you be able to do it? If not then I would avoid rebuilding this motor.

We can give advice but talking a novice through a full rebuild is risky since there is a lot of background experience that needs to be in place by the actual rebuilder that we can't pass on over the net.

 

[POPPS]

And have a peek at the cylinder head, it may be imbedded with metal fragments.

 

[mikidymac]

Cylinders will need to be bored oversized and oversized pistons and rings fitted.

 

[andy.262]

So I think I'm going to give it a shot. I figure, there's only one way I'm ever going to learn how to do this sort of thing, and it might as well be on a machine like this that's not worth too much in its current state. I like to do my own work on things and this stuff is pretty interesting to me, even if I don't know too much about it yet.

Absolute worst-case, there's a mint 1999 SPX on Craigslist right now...

I have the shop manual for torque specs, and I'll have to go find the right types of Loctite. For the cylinders, am I better off looking for a local place that can bore them, or shipping them out somewhere to be bored? How do we feel about the piston kits from SBT, are they any good?

 

[AKnarrowback]

Go for it!

Take your time, be patient, follow the shop manual and ask us questions. No need to buy a new machine if you get this one done right, and you will. Unless the other is cheap enough, then you will have two.....

Take pictures of what is left of the rave valves, both sides, both valves.

 

[andy.262]

I know I didn't pull 2 full RAVE valves worth of bits out of there, so there's definitely some pieces somewhere else. These things literally blew apart - more so than any pictures I've seen others posts. Maybe (hopefully) the bits I can't find got spit out the exhaust?

After looking around for a bit, my current plan is to get new RAVES from Bay Area Powersport's EBay shop, and then send the cylinders, pistons, and new RAVES to Full Bore for the top-end rebuild. The extra $25 to have them shave the new RAVES down to match the over-bore seems like its worth it to me. Plus if I have them do the rebuild I won't have to worry about ordering over-bored pistons and finding a machine shop and all that.

 

[mikidymac]

FullBore has been slow this season.
I have been sending all my machine work to Group K for 25 years and have never been disappointed.
I send him the cylinders then he calls me when he knows what size pistons to order and I just have them shipped to him. I like OEM pistons but WSM are good for a stock rebuild and their full gasket set isn't too bad either but I like to use OEM crank seals.

 

[andy.262]

So I got the engine out, way easier than I thought. But now I'm wondering...

Is this really going to be cost-effective compared to just getting a reman engine already assembled?

Even if I go through the crank as mentioned and don't need any new parts, how likely is that 22 year old bottom end to survive the freshly restored top-end? Am I going to end up with a reman engine anyways?

I do plan on keeping this ski for a long time so maybe it makes more sense to just get a reman engine. I keep going back and forth in my head between trying to rebuild this one, or getting a reman. Maybe someone here has some insight that will sway me one way or the other.

 

[mikidymac]

If it has a lot of hours and you are going to keep it well into the future, do yourself a favor and do a full rebuild.

A OEM crank and good rebuild will be better than any aftermarket engine exchange.

 

[RJO]

I am in the same situation. Is it worth putting $1,600 in a $2000 watercraft. That’s the price from SBT on a standard engine, gasket kit kit and shipping. I tried calling SES and never got a return call, and am not comfortable with them from what I have read about them.
It is a 2000 GTX Millennium Edition that is in great shape.
Does anyone have an idea of what the value would be with a new engine. I got almost 300 hrs out of the original engine.

 

[mikidymac]

The value is about the same as a used engine to be honest. A buyer only cares if it is running.
The only reason to dump money into a rebuild is if you are going to keep it.

 

[Spunbearing]

I was wondering what would cause this? I am working on a 1997 SPX myself and I was going to rebuild the RAVEs with a rebuild kit from OSD. While I am doing this is there something I should be looking for?

 

[mikidymac]

Not really, this is a really rare occurrence.

 

[Spunbearing]

Well that is good to know. The OSD kit includes the following:

• Includes Two (2) New Housing Gaskets
• Includes Two (2) New Viton O-Ring (Replaces 420430110)
• Includes Two (2) New Bellows (Replaces 290260723 290260728 420260723)

One of my housing gaskets is for sure leaking so this should take care of it. Do you guys ever replace the springs or mess with different adjustments on the cap for spring tension?

@andy.262, did you ever find a cause for this? Is it possible that the engine started to let go and debris from cylinder took out the RAVE valves? I would think that a running engine would blow "most" of the debris out the exhaust instead of sucking it back into the engine. I wonder what the exhaust port looks like.

 

[andy.262]

Still not sure what the original cause was. The exhaust port itself looks fine. I do know that the metal fragments did in fact make their way into the crankcase, because today I fished a few out using a long magnet. I'm working on tearing down the bottom-end so I can clean the rest of them out and rebuild.

Sorry it took so long to respond, for some reason I never got a notification for your post even though I'm "watching" this thread.