Valves got louder then BAM!

[bleeble]

I DO have a 16v motor. The top end is toasted. The lower is fine, as are likely the pistons, and maybe even the jugs. ( I would bet so) I have NO USE for the motor, as i dont care for the 16v motors much (there are a couple of the bigger 16v GSs i wouldnt mind owning) So I HAVE THE PARTS.

I'm curious: What is it that you don't like about the 16 valve motors?

EDIT: Should I even bother removing the cylinders?

[TheCafeKid]

I'm curious: What is it that you don't like about the 16 valve motors?

Hrmmm well let see. You have a dead one in your bike, likely because it wasnt getting oil. I have a dead on on my bench, surely because it wasnt getting oil. They also have plain bearing cranks. And to be frank, i think they are ugly looking. But, thats entirely just me.

[Griffin]

Well I like the 16 valve motors better than the 8 valve motors, so there!

Actually, the second generation GS750 ('80-'82) has a pretty good track record of reliability. I think the toughest GS motor ever made is probably the original 8 valve GS550 though.

You should be able to find a decent used 16 valve GS750 motor fairly cheap. For the GS series, it was second only to the 8 valve GS550 as far as numbers imported to the US go.

I can check at Cycle Recycle II here in Indy for you. He's got about 50 old air cooled inline four engines in the back room.

[rapidray]

Listen Bleeble, I build & rebuild GS motors ALL the time & if money is the issue just buy another motor. It can EASILY cost you $600.00 to 1000.00 to rebuild your motor CORRECTLY. You can find used 16 valve 750 motors all day long for $300.00 or less. If you have the money & the time, I say BUY ANOTHER motor as the one you have STILL needs too many parts replaced! You can also bolt in a 16 valve 1100 or 1150 motor you know! Good luck whatever you decide, Ray.

[bleeble]

The biggest issue I'm going to have with buying another motor is transportation. I doubt my little I30 is going to fit a motor in the trunk. Even if one does fit, I don't know how in the world I'd get it out by myself.

If you have the money & the time, I say BUY ANOTHER motor as the one you have STILL needs too many parts replaced!

This is what confuses me. I haven't even opened the darn thing and everyone keeps saying things like "Oh, X, Y, and Z are toast and need to be replaced. Your valves weren't getting enough oil, that's why your connecting rod broke. etc." :roll: I mean, I really appreciate all the suggestions and advice, but where are you guys getting this information?

Griffin, I may take you up on that offer. If you happen to be out there anytime soon, see if you can spot a good deal on an '80-'82 750 for me.

[Dogma]

...
This is what confuses me. I haven't even opened the darn thing and everyone keeps saying things like "Oh, X, Y, and Z are toast and need to be replaced. Your valves weren't getting enough oil, that's why your connecting rod broke. etc." :roll: I mean, I really appreciate all the suggestions and advice, but where are you guys getting this information?...

So, uh, when do you think you'll get to open it up? I'm curious to see which of all these speculations is correct. 50 brownie points to the winner!:-D Still, it's hard to think of something that could stop the engine like that without thrashing it, whatever the cause was. Especially since the stop was preceded by sudden mechanical noise.

[bleeble]

So, uh, when do you think you'll get to open it up? I'm curious to see which of all these speculations is correct. 50 brownie points to the winner!:-D Still, it's hard to think of something that could stop the engine like that without thrashing it, whatever the cause was. Especially since the stop was preceded by sudden mechanical noise.

I'll be spending the night doing the studying I neglected today and I have class all day tomorrow. So possibly on Wednesday. Friday at the latest.

[TheCafeKid]

The biggest issue I'm going to have with buying another motor is transportation. I doubt my little I30 is going to fit a motor in the trunk. Even if one does fit, I don't know how in the world I'd get it out by myself.


This is what confuses me. I haven't even opened the darn thing and everyone keeps saying things like "Oh, X, Y, and Z are toast and need to be replaced. Your valves weren't getting enough oil, that's why your connecting rod broke. etc." :roll: I mean, I really appreciate all the suggestions and advice, but where are you guys getting this information?

Griffin, I may take you up on that offer. If you happen to be out there anytime soon, see if you can spot a good deal on an '80-'82 750 for me.

Well, I get my information from both experience and sensibility. Just tonight i was working on an 8 valve motor that was only firing on two cylinders. But guess what? It was running. It didnt make a bunch of clatter and then slam to a halt. The only thing that can really do that is lack of oil flow or a spun/seized crank (usually do to lack of oil flow:-D) . The pistons will move up and down all day long as happy as you please, firing or not, untill the unburnt gas dilutes the oil to the point that it no longer lubricates properly, or they cease to get oil. Im personally not even sure its a connecting rod, wrist pin, snapped crank or anything else. The only thing i am pretty sure of is that your motor wasnt getting oil somewhere, likely causing the piston to sieze in the cylinder and break whatever is broken.


Im not proclaiming to be all knowing about these motors or any motors, but I can take a semi educated (only from experience ) guess on whats going on. Tonight however, I am stumped on this particular project, so who do i turn to for advice? You guys...lol Ive successfully learned how to strip and rebuild the top ends on these things by thumbing manuals and mostly by the eons of experience from those on this board, so when they talk, I listen. I may not always agree, or even explain things well enough for THEM to state thier thoughts, but i listen.

[bleeble]

Sorry I snapped at you guys before. Frustrating day... anyway, I had my digicam out so I thought I'd snap some pictures. Let me know if you see anything horribly wrong because I have no idea how things are supposed to look. \\/

(pictures in following posts)

[bleeble]

Pistons

Cylinders 1 and 2




Cylinders 3 and 4

[bleeble]

Valves

Cylinders 1 and 2



Cylinders 3 and 4



I had some pictures of the top of the head/valves, but they turned out blurry. If you still want to take a look, they're here: http://s292.photobucket.com/albums/m...e/GS750/Motor/

One thing I did notice is the clean spot on piston number two and the bottom of the head. I guess that "thud" was from the piston flying up and hitting the top?

EDIT: And that oil got on the valves after I took it off. Yes, the exhaust valves on cylinder 4 were black.

EDIT 2: Oh yeah, I didn't have time to pull off the oil pan yet. My school schedule is really kicking my butt. In fact, I have a paper I should be writing right now...

[psyguy]

to my eye (only semi-experienced eye though) spies only that clean area on #2 that you mention as well
that's good news i think

next stage, take the barrels off, that should reveal some damage i expect

[Suzuki mad]

Try and get the barrel off the best way you can without damaging the externals of the barrel.

At that point you will know how bad the damage is.

Looking at the pictures oily No4 looks like the valves are slightly open. Thats only oil seals which are easy to replace. Looks like No2 has bumped the bottom of the cylinder head from the marks on the picton and the head. With the position of the pistons in the picture that looks correct so a little inconculsive at present as to what has happened.

From the look of the parts of the bores that are showing theres no damage from the piston at present so the barrels may be salvaged.

Suzuki mad

[bleeble]

Doooooom!

Oil Pan

[bleeble]

Piston 2