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Leak Down Test problems

  • Thread starter Thread starter Karstan
  • Start date Start date
Wait, so, according to the manual the cylinder block (the part with the actual pistons) should just pop right off at this point, right? Mine won't budge. Am I reading this right?
 
Stuff a rag around the case opening, use a pick and screwdriver, cover it with your hand as it comes out so you can control it when it pops out. If your not careful the cir clip will launch itself in to the garage never land, then you gotta wonder where it went, I like to know exactly where they are.
 
A slight tap with a rubber mallet on either side(NOT ON THE FINS) and she'll come loose, just gotta break the seal of the base gasket.
 
When was the last time that thing was run?
If I was you I would bring the head to a engine machine shop along with a set of new valve seals and tell them to do a valve job. If the valve faces look that bad I couldn't imagine what the seats look like, IMO probably more than a valve grind could help.
 
gearhead13 said:
When was the last time that thing was run?
If I was you I would bring the head to a engine machine shop along with a set of new valve seals and tell them to do a valve job. If the valve faces look that bad I couldn't imagine what the seats look like, IMO probably more than a valve grind could help.
Click to expand...

It was my daily driver up until the end of October. The valves seem to be sealing fine now, and they seem to have cleaned up pretty nice. But I'm not sure what they're *supposed* to look like. As it is, I'm planning on replacing the valve stem seals while I have the head off, but you think it needs more?
 
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Karstan said:
It was my daily driver up until the end of October. The valves seem to be sealing fine now, and they seem to have cleaned up pretty nice. But I'm not sure what they're *supposed* to look like. As it is, I'm planning on replacing the valve stem seals while I have the head off, but you think it needs more?
Click to expand...
It might seal ok with gas in the ports, but the valves need to be removed and inspected, the springs have to come off for seals anyway, and depending on what the seats look like, it might need a valve job other than valve grinding paste. If the faces of the valves looked that bad, the underside and seats cant look to good.
How many miles are on it?
 
gearhead13 said:
It might seal ok with gas in the ports, but the valves need to be removed and inspected, the springs have to come off for seals anyway, and depending on what the seats look like, it might need a valve job other than valve grinding paste. If the faces of the valves looked that bad, the underside and seats cant look to good.
How many miles are on it?
Click to expand...

Exact mileage is unknown due to a broken odometer, but it's probably in excess of 50,000 km/31,000 miles (what it reads on the broken odo).
 
Karstan said:
Yeah, that's kind of what I'm thinking. How do I get the pistons out? The manual calls for a special tool, but that tool seems to have been discontinued.
Click to expand...

No special tool.....just more money! To get the "pistons out" just pull up the cylinder block. Once you do that you will need new rings and a base gasket. Careful doing it though. Often they are stuck on there pretty good and you may be tempted to jam a screwdriver (or something similar) in between the block and the case to try and pry it loose. That technique often leads to gouged parts and/or broken fins on your block. Instead I like to use a putty/spackling knife and work my way around to loosen it up. Takes longer but the results are damage free.

To get the pistons off the rods you may need a "piston pin puller". You can improvise one for cheap. All you need is a full threaded bolt or threaded rod that is approx 2 1/2 to 3 times the width of the piston and will fit inside of the piston pin. A washer and nut that is about the width of the pin and will fit inside of the pin boss on the piston. And a large socket and washer that are larger than the pin and which the pin can slide inside of. Remove the circlips (stuff the crankcase full of rags in case you drop the circlip), slide the bolt through the socket, washer and pin, attach the washer and nut and tighten the bolt. As you tighten the bolt, it will slowly draw the pin out and into the inside of the large socket and release the piston from the rod.
 
New rings, bottle brush hone the cylinders (assuming no deep marks), lap valves, new valve stem seals, and OEM gaskets. Most aftermarket gasket kits are inferior, some significantly so. Athena for example (the kits with green gaskets) make some really crappy base gaskets that are sure to leak. Big red flag on that.
 
Thanks for the advice everyone! Especially you, OldSkool. The details you provide are super helpful!

So I'm about to order all the parts I'm going to need and want to make sure I get everything.

1) Cylinder base gasket
2) valve guides x16 (nobody's mentioned these, but the manual says to replace them if you're going to remove them. What do you guys think?)
3) valve guide oil seals x 16
4) valve guide rings x 16
5) piston ring sets x 4
6) Head gasket (sigh, THAT'S an expensive gasket)


Edit: I just added it all up and I'm looking at about $450! Gah!
 
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It's very unlikely that you will need to replace the guides. That's a job for a professional anyway since a full valve job would have to be performed afterwards (at considerable cost).

As for gaskets, you might want to check ebay under "gs750 gasket" and see what you can find. Often times you can get OEM gaskets for cheap there... http://www.ebay.com/itm/SUZUKI-GS75...cycle_Parts&hash=item35bb416785#ht_612wt_1163
 
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