engine seized momentarily due to oil possibly

Hello everyone, just wanted to say thanks for the awesome site, it has been a help with issues before and I know someone will try to help with this one.
Recently I bought a 1976 kz750 (twin), it has only 7,6xx miles on it and is a beautiful bike that has never really been ridden. Anyways, the only known and suspected problem when I bought it was the starter clutch(I was told), the electric start won't work all the time, sometimes it will quit trying to turn the motor over and just make a whirling type noise. It will work 75% of the time, but only if the engine is warmed up.
The other day I took it for the second drive, 1/2th way back home (50 miles about) i stopped at a store and bought something and of course turned the bike off when I went inside. Upon returning outside I went to start the engine and it started with the electric starter immediately and then turned off, seemed to be due to lack of fuel(sometimes a low idle was stll rough). When I went to start it back up the electric starter immediately made that sound, so I went to kick start it and wala the engine was almost seized, almost. Eventually got it to turn without much force, pushing the bike back and forth in gear. After I broke it free(in the parking lot still) i tried to push the kick start again(light and slow). It would turn over but not the easiest, took a little more force than usual and a slight squelling noise(sounded like metal on metal unlubricated), so i stopped messing with it till i got it home.
Once i returned home i took the sparkplugs out and put a little bit of oil down the plug hole and tried turning it over, it immediately started to feel normal again, no noise(other than a slight rattle and whirl by the starter clutch, but that noise is the same as when the electric starter fails).
It seems as if the oil flow to the pistons was clogged, oil pump was bad/clogged, or the quality of the oil was bad. Seeing how the person I bought it off of said he had drained the oil and I had already put new 20w50 special motorcycle oil in it I assumed the pump had failed for some reason or another. So I took off the oil pan and removed the oil pump, only to find that the oil pump worked!
So now I am assuming that the person I bought it off of hadn't fully drained the old oil and that had caused it to became overheated and swell, i assumed this as time seemed to help "cure" the original seizure problem. Or possibly my cabs overfilled or fuel pump failed and caused fuel to enter the oil and ruin the oil, it had a slight fuel smell to it(oil I removed) and a little bit of metal in it, but not much, it also had what appears to be rust in the oil.
I looked up the through the bottom and the cylinders appear to be fine as does the timing of the engine, pistons, lower bearings(as much as I can tell) and the arms. This is my first bike and 4 stroke engine I have worked on so I decided to ask for your help.
Is there any way no damage occurred to the internal components of the engine? It sounds fine when I turn it over with the kick starter and only has minimal resistance(there is no oil in it as I dropped the pan today, so I assume that is the reason for the resistance). As I stated earlier this bike has only 7,6xx miles and everything is original(appears to be). I am not turning it over much though due to the pan being dropped.
I know the majority of people will say to take the head off and inspect the engine, which I will most likely do if its required, I just would rather not cause any problems. I'm just wondering what the chances of not causing damage to the engine, and what you would have me do in a situation as this. I'm low on money but have plenty of time.
I apologize if this is long but I wanted to include all information and details that I could.
I thank you in advance for your help and time in reading this, I'm slightly mechanically inclined and will do all the work myself even if I need to take the motor apart and put it back together(rebuild if necessary, any work that would need done I will do actually).

Since there's a problem w the starter or starter clutch, I'd look into that.
I'd guess something to do w the starter caused a seizure?

If you don't want to take it apart, your options are to change the oil and filter and try running it. If the carbs are dumping gas from flooding, that needs to be fixed ASAP.

If the bike sat a long time it's possible the cylinder walls may have a rust ring where the rings sat against them (?)

The 750 twins are known to have starter clutch problems. Used ones are available from the online dismantlers.

It siezed because it got to hot, the question is, how did it get that hot? Did you spend some time with the bike idling and not moving?

You scored the piston and cylinder wall, but you can run it as long as you don't overheat it again.

Your Oil Pump does not supply oil pressure to the Pistons. The pistons are Oiled by Splash. This means as the engine is running oil is Splashed by the rotating parts up onto the cylinder walls being scraped back off by the Oil Control Rings. So while its a good Idea checking the pump and pickup screen for cleanliness, you are not making the Pistons get more oil.
If you suspect the pistons had momentarily seized, then i would do a compression test, as the rings could be stuck in their grooves= bad news. If this checks out, good compression, then move to the Starter Clutch repair.

Thanks everyone for your replies, it's good to know there are people willing to help me along with this transition as it is my first motorcycle.

(@STEELL) I thought I sat with it long enough idling, but no matter what the idling was a little rough, but as time went on it seemed to get better.

(@everyone)I believe at this point the seizure was due to contamination of the oil, I took the previous owners word on saying he drained the oil from the bike.... I shouldn't have. I guess I really cannot trust anyone but myself... Foolish on my part... But, PLEASE continue reading.

Ok, so after taking the oil pan and pump off and looking up through the bottom it "appears" that the walls and the pistons were fine. There did not appear to be any rust where the cylinders could have sat for awhile and it did not seem to have any scores or abrasions as I could see the reflection perfectly around the walls( I made sure to see all the way around the walls where visible, turning the motor when needed). This was from looking up the bottom, so there is an area you cannot see as the piston will be there. I really think I lucked out and did not cause any damage
but
(@motor head) I will see if I can borrow the tools from the autozone up the road and do a compression test on the engine(asap) because at this point I want to be 100% sure I did not cause any damage. Hopefully they have the part... I can tell from rotating the engine slowly with the kickstand and from letting it sit (idling) that the compression is there and it is even from one muffler to another(as much as a human hand can tell), but it could very well be the issue. Although, I should mention that the oil I poured down the spark plug holes stayed there(majority of it), so would that prove anything regarding compression or just prove the pistons are airtight?
Either way it will be pretty exciting to take the head off and visually inspect it as it will be my first time, working on the bike is almost as fun as riding it!
What should I replace other than all the gaskets when I take the head off?(not too important to answer here compared to the other questions)

Problem #2 (Do not know if i should have started a new thread, sorry if I was, kept it hear in case the problems were related somehow)
After taking the oil pump off and inspecting it I decided to put it back together and try starting it up based on Bounty Hunter's response, figured it couldn't hurt to try if it wasn't seized anymore and that when the engine rotated it didn't seem to make any noise or cause any damage. I will be doing the head soon anyways to do the compression test as suggested by motor head.

It went well!!! The engine started up rather quickly, finished burning some of the oil that was left in the head(what i couldn't siphon and blow out with compressed air) and then it started having a rough time idling(about 15 minutes later and a short ride).... This was happening before the seizure but not quite as badly.
I think it was due to it running lean as I would have to pull the choke up a little to save it, then the weirdest thing would happen moments later after pulling the choke up, sometimes it would "switch" all of the sudden and act like it was too rich as well and then stall( not from the choke, literally seemed like a switch would get turned on and off, no matter what the position of the choke was)... It seemed to me that something in the carbs was not functioning properly, so I decided to take the carbs off and inspect them.
2 hours later, after blowing every single little area out and making sure that none of the parts were damaged I put the carbs back together and put them back onto the engine.

NOW the bike will not start at all, and when it does it will instantly bog down and die. Honestly I feel the engine is running too rich now, I know I cleaned a couple of obstructed passage ways as they would not allow a good air flow(was obstructed but not clogged), but now they are all clean and free of debris. I also noticed at this time the jet needle was on groove number 4, providing a slightly richer mix in the "main system" area of the carbs(1/4th-3/4th throttle), and maybe could effect the starting system or overall quality of the carbs?(I dont know, assume it could)

Basically, when I cleaned the carbs I feel that I opened up some passage ways more and now it is running rich(I do believe as starting fluid will not help, the spark plugs get lightly fouled, and it runs worse when warmed up)... I checked the spark plugs hooked into the ignition coil wires outside of the engine and they produced a spark so I believe its fuel related instead of electrical(unless it is my ignition timer?, but it appeared to be timed when I looked at the spark, well as much as a human eye can tell based off of how a 4 stroke engine works internally)

So, I have a couple of theories on why this is happening and will run them by you.

A) My bike has pods on the carbs instead of the actual air filter housing unit.... I hear this can make it so you have to re-jet your carbs. Is this true? If so would pods cause my bike to run lean or rich? Looking at the prices of the connector pieces (and how they are discontinued) running from the carbs to the air pods I might just re-jet the carbs depending on price, but I would need to know more about it first.
I was wondering what people's responses would be on this subject.

B.) The jet needle! The cotter pin is in groove number 4, from what I understand about carbs, this provides a somewhat more rich mixture than the normal 3 spot. When I first got the bike it was obviously running lean as the previous owner was using the choke to provide a correct fuel mixture... You could tell that the bike had not been ridden with the choke all the way down in a long time, and of course the needle was readjusted to the number 4 spot.
I was going to try and move the cotter pin up a groove or two and then see what would happen with the starting and idling aspect of the bike. I already took the carbs apart so I know everything is fine... All I need to do is get the fuel level tool(special tool) from autozone(if I can) and check the fuel level inside the float chamber and make adjustments as needed to the floats(or replace them).

c) There are 4 hoses running off the carbs towards the back of the bike and the oil breather tube... I know some are due to the air housing unit not being on the bike, but I am not sure exactly if they all should be hanging down. I know the one tube looks as if it could connect from one carb to another, so I took a picture and will load it up. If it is supposed to hook the carbs together, could this be my problem(?).

**In the picture you will see the choke lever, next to the choke lever is the hose that runs into nothing, I was just wondering if this was supposed to hook up into the other carb or run off into the back of the bike as well. You can see my fingers on the same hose running off the other carb, where I theoretically believe the first hose should/could connect to, thus connecting some kind of passage way from one carb to another. I cannot find this in the service manual thus why I am asking you for advice.**

Sorry this is so long, but I am honestly stumped... It just seems to me(my gut iunstinct) that it is fuel/air related. I have felt this way about it since the beggining, thus why I cleaned the carbs. I am on a tight budget and do not have money to waste so I am trying to fix things based on their priority level. I DO plan on checking the starer clutch, and then replace it. That is priority number 1 right now, but I really want it to idle and run fine before dropping that in as it is the most expensive part and I wont be able to replace it for another week.

Either way, thanks for taking the time to read this guys, I tried to figure it out by myself and will try moving the cotter pin on the jet needle to see if that helps at all... and really blow the starter area out again literally as soon as I am done writing this.
I am willing to do ANYTHING and EVERYTHING that will be needed to fix this bike myself! So please keep that in mind.
Thank you again.
(if the picture is not in this post it will be followed in its own post shortly afterwards)
[attachment:1]C:\fakepath\carb.JPG[/attachment]

carb photo showing the hoses

Trwkz750 wrote: I took the previous owners word

Never EVER do that!!!!

First thing you do when you buy a bike, no matter what condition, is drop the oil & filter.

It's an air cooled motor, if there is no air flowing then it will overheat and seize.
If you're going to idle more than 5 minutes then you need a fan blowing on the motor to keep it cool.

The top part of the cylinder is the hottest, so when it seizes it does so at the top of the cylinder, the part you can't see from the bottom.

Contaminated oil has nothing to do with it.

That's fifty plus years of experience talking, but feel free to ignore.

Yea, I'm dumb for listening to him. I will agree to that, but never again. Was extremely embarrassed to mention it.

I know it's air cooled, that's why I would go for short drives. Honestly it never really ran steady past 5 minutes without me going for a drive to cool it down. When it seized I was doing 50mph+ the whole ride, so it had to be the oil that caused it to seize... I literally pulled over to get cigarettes then came out to start it and wala, seized.
I can take apart the head and look and see if there was any damage, but wouldn't it continue to make sounds and run crappy if something were wrong. What kind of "silent" damage would occur other than the walls and pistons getting messed up? I have ran it on 3 separate occasions since it seized, it only started to give me trouble since i took the carbs apart and cleaned them, and as I stated its running lean(I'm pretty sure) now.

I will always listen to 50+ years of experience, I hung up my pride at the register page of this forum, I am here in admittance that I am only 24 and have a lot to learn, lol.

You keep assuming the cylinders are seizing.

An engine can seize in alot of places, crank bearings, cam bearings, etc.

thanks I needed to start reading more

Trwkz750 wrote: Hello everyone, just wanted to say thanks for the awesome site, it has been a help with issues before and I know someone will try to help with this one.
Recently I bought a 1976 kz750 (twin), it has only 7,6xx miles on it and is a beautiful bike that has never really been ridden. Anyways, the only known and suspected problem when I bought it was the starter clutch(I was told), the electric start won't work all the time, sometimes it will quit trying to turn the motor over and just make a whirling type noise. It will work 75% of the time, but only if the engine is warmed up.
The other day I took it for the second drive, 1/2th way back home (50 miles about) i stopped at a store and bought something and of course turned the bike off when I went inside. Upon returning outside I went to start the engine and it started with the electric starter immediately and then turned off, seemed to be due to lack of fuel(sometimes a low idle was stll rough). When I went to start it back up the electric starter immediately made that sound, so I went to kick start it and wala the engine was almost seized, almost. Eventually got it to turn without much force, pushing the bike back and forth in gear. After I broke it free(in the parking lot still) i tried to push the kick start again(light and slow). It would turn over but not the easiest, took a little more force than usual and a slight squelling noise(sounded like metal on metal unlubricated), so i stopped messing with it till i got it home.
Once i returned home i took the sparkplugs out and put a little bit of oil down the plug hole and tried turning it over, it immediately started to feel normal again, no noise(other than a slight rattle and whirl by the starter clutch, but that noise is the same as when the electric starter fails).
It seems as if the oil flow to the pistons was clogged, oil pump was bad/clogged, or the quality of the oil was bad. Seeing how the person I bought it off of said he had drained the oil and I had already put new 20w50 special motorcycle oil in it I assumed the pump had failed for some reason or another. So I took off the oil pan and removed the oil pump, only to find that the oil pump worked!
So now I am assuming that the person I bought it off of hadn't fully drained the old oil and that had caused it to became overheated and swell, i assumed this as time seemed to help "cure" the original seizure problem. Or possibly my cabs overfilled or fuel pump failed and caused fuel to enter the oil and ruin the oil, it had a slight fuel smell to it(oil I removed) and a little bit of metal in it, but not much, it also had what appears to be rust in the oil.
I looked up the through the bottom and the cylinders appear to be fine as does the timing of the engine, pistons, lower bearings(as much as I can tell) and the arms. This is my first bike and 4 stroke engine I have worked on so I decided to ask for your help.
Is there any way no damage occurred to the internal components of the engine? It sounds fine when I turn it over with the kick starter and only has minimal resistance(there is no oil in it as I dropped the pan today, so I assume that is the reason for the resistance). As I stated earlier this bike has only 7,6xx miles and everything is original(appears to be). I am not turning it over much though due to the pan being dropped.
I know the majority of people will say to take the head off and inspect the engine, which I will most likely do if its required, I just would rather not cause any problems. I'm just wondering what the chances of not causing damage to the engine, and what you would have me do in a situation as this. I'm low on money but have plenty of time.
I apologize if this is long but I wanted to include all information and details that I could.
I thank you in advance for your help and time in reading this, I'm slightly mechanically inclined and will do all the work myself even if I need to take the motor apart and put it back together(rebuild if necessary, any work that would need done I will do actually).