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SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

This project is already like 3 days in. I'm not completely new to engines; I've done a car head gasket once, and a valve cover gasket, but I'm not at all qualified to be doing this.


Was driving down some country roads the other day, and slammed on my breaks when I saw a 1994 Tigershark PWC for sale for $350. The trailer is one of the nice zinc coated ones. Wrote down the guy's number. Spoke with him, the engine "needs work", he doesn't know what's wrong with it, but he thinks it needs piston rings. I can turn the crank, so it's not frozen at least. No battery, whatever! SOLD!

Registered both it and the trailer, installed a hitch on my tiny rear end ford focus, and drove off into the sunset.

The goal here is to
  • Figure out what's wrong, replace missing and damaged parts
  • Convert to premix because oil injection pumps scare me

The next day, began inspecting stuff. A bunch of small stuff looked wrong. The carb was half off, both bladders damaged($15). Bilge pump disconnected.

It's a 640CC engine.

Time to get to work! Got the shop guide.

Followed the guide, disconnected everything and unmounted the engine. Other oddities pursued. Missing an exhaust manifold bolt. Missing random gaskets.


Deadlifted the engine out of the PWC, raised it above my head screaming, "WITNESS", and threw it to the ground.


Where we're going, we don't NEED head gaskets. Yeah, it's just, totally not there. Ok then.


Missing an exhaust gasket, intact one is burned to poo poo.


The cyls look OK. Both have an inner diameter of 2.980 from multiple points, they are true.


Both pistons measure 2.975in from multiple points. But this piston looks bad. It measures ok, from both normal points and the scrape point, but I can feel the scrapes with my fingernail. Does this need to be replaced - or if it can be sanded down with fine grit sandpaper, is it OK?


Piston ring does look shot, book says the gap is supposed to be 0.20-0.80mm, looks more like 5mm.

The crank looks OK looking down on it from the top, no water got in.

So...my questions would be....


1) Should I replace the piston, it looks within spec according to the calipers. If it can be buffed out, OK to reuse? Slightly worried that if I replace it, the wrist bearings, and pins, that the rods might wear out funny since those aren't getting replaced.
2) Should I open the crank? Would probably have to get new seals. Slightly worried I might not get it back together again properly if I do that. I'm not intending on replacing anything down there. Was thinking about sloshing around some premix and sticking a magnet down there to pick up any filings.
3) The cyls measure and look OK, should be OK to hone with a drill and one of those 3 stone bits, right? Don't need to send them in for boring.

SSH IT ZOMBIE fucked around with this message at 18:02 on Jun 21, 2015

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INCHI DICKARI
Aug 23, 2006

by FactsAreUseless


I can't speak on the rest of it but for the love of god do not reuse that piston.

InitialDave
Jun 14, 2007

I Want To Believe.


SSH IT ZOMBIE posted:

1) Should I replace the piston, it looks within spec according to the calipers.
Use a micrometer. Several measurements at different points. But:

14 INCH SLIT posted:

for the love of god do not reuse that piston.

Unsane
Jul 16, 2003



how bad is the corresponding scrape in the cylinder wall from that piston?

Unsane fucked around with this message at 20:38 on Jun 21, 2015

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

Unsane posted:

how bad is the corresponding scrape in the cylinder wall from that piston?

I could not see a scrape! So that's why I was confused. Someone suggested I hone the cylinder wall before making any decisions a couple hours ago. Was originally going to do all that after I get parts.

After I started honing, the high points and damaged points became apparent. After several dozen minutes per cyl, the scuffs are just barely visible. Going to keep at it, and remeasure to make sure I didn't significantly widen the diameter.

Was trying to be cheap, and get away with a gasket and piston ring kit only, but it looks like I'm going to have to replace the pistons. That kit is $200.

SSH IT ZOMBIE fucked around with this message at 20:57 on Jun 21, 2015

INCHI DICKARI
Aug 23, 2006

by FactsAreUseless


Honestly for something like you just did you're going to need a dial bore gauge and see if it's ovalled.

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

14 INCH SLIT posted:

Honestly for something like you just did you're going to need a dial bore gauge and see if it's ovalled.


Been using these - not good enough?

InitialDave
Jun 14, 2007

I Want To Believe.


SSH IT ZOMBIE posted:


Been using these - not good enough?
No, those should be fine, but ensure you're using them correctly, and take measurements in multiple positions.

INCHI DICKARI
Aug 23, 2006

by FactsAreUseless


That's actually better than I expected, I was picturing like an oreilly's vernier caliper in my mind like I'd use to quickly check brake rotors. I was just going off what I'd expect to see someone do who was just starting out so you're ahead of the game already.

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

Jeeze, I shaved off 2.5 thous with a stone hone tool. The cyl walls needed that much to remove all the scuffs.
It's still within spec, ordering a whole top end kit!

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice



Someone suggested I file down the exhaust ports and chamfer both intake and exhaust. Most of the ports are already rounded - but the exhaust ports, is it normal for the cyl to extend like that beyond the port? Or should I file it down? Not sure if it's intentional engine design or like a casting issue.

The exhaust ports are less chamfered than other ports.

wildemere
Nov 19, 2013


Have a read of this. Its a bit old but still revelant. Gordon Jennings Bible.

https://www.google.com.au/search?q=...SE9Lr8AXWvJ2QAQ

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

wildemere posted:

Have a read of this. Its a bit old but still revelant. Gordon Jennings Bible.

https://www.google.com.au/search?q=...SE9Lr8AXWvJ2QAQ

That's a really good read, thanks!

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

For what it's worth - I got it together. It's pretty fast!
But the hull has a leak! drat it!

I'm probably going to take it to a friend's, lift it, and put it in the grass tilted on it's side to work on it.

Could one of those 2 ton engine lifts + http://www.amazon.com/Erickson-0200...g/dp/B0000BYASB actually lift it, do you think? It's 400 lbs. Trying to find pictures of people actually doing that, can't find any, leading me to believe it can't be done though it looks like it could on paper.

Elmnt80
Dec 30, 2012

I write my poems in the dirt with an oily rag
I have to wear a gas mask just so I don't gag
I got a SOCOM scout and twenty extra mags
And a couple severed heads in my bug-out bag






Your issue would probably be height/size more than weight with that harness and the engine hoist, so long as it is properly balanced. What exactly is it you want it up in the sling for? Moving it off the trailer and to a work area or something else?

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

It's about 38 in wide and 400 lbs.
Yes, moving it off the trailer and to a work area without needing two people. Or working on hull repairs from the lift with some extra support under it.

I also really wished I had an engine lift when I had rebuilt the engine on this thing.

Jetski stands 24 in high on the trailer. Looks like the boom goes up to 78 in high. The sling length is 35 in.

I...think the clearance would be OK?

SSH IT ZOMBIE fucked around with this message at 03:44 on Jul 28, 2015

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

Fixed the leaks with a bunch of marine grade epoxy and fiberglass.

https://www.youtube.com/watch?v=rzll4coyxFY
Broke in the engine, let it rip. Works well.

Exploded the head gasket after 20 hours, haha


Ordered a new one, I overtorqued the head bolts some. This time going to do it to spec, and use threadlocker I guess as I only overtorqued them because they kept coming loose.

No cyl damage from what I can see, fortunately.

SSH IT ZOMBIE fucked around with this message at 05:28 on Aug 25, 2015

DefaultPeanut
Nov 4, 2006
What's not to like?

Head / cylinders check out for flatness?

SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

DefaultPeanut posted:

Head / cylinders check out for flatness?

I didn't check! The one takeaway from all this is I should have just sent the head out to get bored and checked. Also, both sides of the gasket show the area around the cylinder unraveling like that. If it wasn't true, shouldn't the damage be localized to a high spot or low spot? The whole thing exploded pretty evenly, which is why I thought it's because I overtorqued or maybe it's a bad gasket. It weighed like half as much as the old one.

Do I need to take the head back off and use that blue paint?
Or can I just use something flat on the head + a feeler gauge?

SSH IT ZOMBIE fucked around with this message at 13:36 on Aug 25, 2015

NumbersMatching320
Oct 24, 2010

RESALE VALUE, MEIN HERR




Pillbug

SSH IT ZOMBIE posted:

Or can I just use something flat on the head + a feeler gauge?

This, but it's gotta be very loving flat- a machinist's straightedge is the only thing that will let you be absolutely sure.
But now that you've overtorqued it it's pretty likely to be warped

Commodore_64
Feb 16, 2011

love thy likpa


I don't know how deep the chamfers are on those head bolt holes, but I would be concerned about local high spots around them after overtorquing. I'm not sure if I should recommend hitting it with a stone, if that will screw up the surface finish too much etc, but on other things like fixture plates and such that's what I normally do. One of these guys http://www.amazon.com/Starrett-380-...ZGJZQJXJ2KC9DJ, a feeler, and a bright light would do you for checking flatness. Or just lug the block over to a machine shop and prepare dollers for handing over.

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SSH IT ZOMBIE
Apr 19, 2003
No more blinkies! Yay!


College Slice

Welp. Lessons learned. The head gasket is 15 bucks and is like 20 minutes of work. It will either work or not I guess at this point.

http://www.amazon.com/Vividia-Porta...ds=scope+camera
Could I pick up one of these, and maybe check it out through the spark plug holes? If I see the gasket eating itself again after several hours I'll know that it might leave me stranded if I take it out far from shore.


If it blows again, I'll weigh my options...send the head out to get machined and bored, new oversized pistons...or try a 30 dollar parted out head off eBay.

Even if I get the head bored and resurfaced, there's no gaurentee that the piston rods are true, or that something isn't cocked in the crank, given the state of the pistons originally.

Edit: Absolutely not on the scope. drat. It'd need to be much smaller than the opening for the spark plugs, so I could get it at the right angle. There's like an inch of space before the head gasket. Probably couldn't even see the top of the cyl wall with those cheap scopes.....argh.

SSH IT ZOMBIE fucked around with this message at 00:16 on Aug 26, 2015

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