How do rings go bad from just sitting

[noiseguy]

I'm betting that the rings are stuck to the piston, and will respond well to a spraydown with a penetratant and running a bit. See if you can get compression above the current 60 PSI without starting then give it a shot.

At worst, you'll be out a set of $30 rings to fix the issue. Bore can't be too bad if it's still turning over.

[Lunytune]

I'm betting that the rings are stuck to the piston.

Okay, I digress. That is one way rings can go bad just sitting.

[noiseguy]

I've heard of that exact issue on the board before; it fixes itself after the scoots been run a bit typically, *if* you can build enough compression to get it to fire up. If it stays low then you have to remove the head and look inside to see what's up. I'm betting he won't need new rings or even a teardown.

[Lunytune]

I've heard of that exact issue on the board before; it fixes itself after the scoots been run a bit typically, *if* you can build enough compression to get it to fire up. If it stays low then you have to remove the head and look inside to see what's up. I'm betting he won't need new rings or even a teardown.

Pump some gas and oil through it and get it up to temperature and those rings just might loosen up. It's worth a try.

If it needs reringing though, I think you could beat $30. I'm looking at this Autotech355 on eBay for... oops, better back off that. It's for AF18 which would work on Elite 94-01. Don't know about Spree prices.

[TLH]

I thought I had posted that I have taken the head and cyl off to check for stuck rings, it looked almost new inside, when I was taking it apart it looked like it had a small head gasket leak so I thought that was it , so I put it back together and still the same 60 psi...

I have not had time to check the crank seals but I'm starting to think that may be part of the problem, when I was putting oil in the engine to re lube eveything after reassembly, after cranking it over to try and start it, some oil started running out of the drive belt case.

[Lunytune]

I thought I had posted that I have taken the head and cyl off to check for stuck rings

Yes you did. Problem with forums is sometimes we get to chasing in a circle and forget what we're supposed to be doing: Gathering data and coming to a viable conclusion.

Rings don't go bad overnight. Usually it's a gradual thing that all of a sudden becomes noticeable in conjunction with something else. Like sitting over the winter, etc. The seal idea is a worthwhile consideration. But if you're going to the trouble of laying the powerplant on the bench and replacing the seals, might as well overhaul the top end while you're at it. Then you know it will be right. Like I think I may have said in this thread and have in others, basic principles: 1. Compression, 2. Ignition 3. Fuel. The seals is not exactly a compression issue, more in the area of fuel, as the seals would cause a vacuum leak or "contamination" (too much air) of the fuel mixture.

Apologies for my part in the rabbit chasing. But one thing about rabbit chasing, when that rabbit goes full circle, you got another shot at it... if you have a good dog.

[TLH]

Like I think I may have said in this thread and have in others, basic principles: 1. Compression, 2. Ignition 3. Fuel. The seals is not exactly a compression issue, more in the area of fuel, as the seals would cause a vacuum leak or "contamination" (too much air) of the fuel mixture.

Your basic principles are correct, and is your view on the seals causing a vacuum leak. But as pointed out by another member bad seals can also cause low compression.

I had to get out of my 4 stroke mind set and let it sink in.

HereÔÇÖs how:
piston moves up , drawing in air and fuel from the carb past the reed valves and into the crank case, piston moves down , reed valves close pushing air up through the transfer ports and into the cyl. piston moves up and it fires.

So if the crank seals are bad, it can push air and fuel out the bad seals, instead of into the cyl, less air and fuel = less compression.






T.

[Bear45-70]

4 Stroke


2 Stroke


2 Stroke DFI

[Lunytune]

Bear, I love your animated graphics, but can bad seals cause low compression? I'm having to think on it, and just had to take a couple of naproxen to help the process... plus a cinnamon pill, vitamin & iron pill.

[Bear45-70]

Bear, I love your animated graphics, but can bad seals cause low compression? I'm having to think on it, and just had to take a couple of naproxen to help the process... plus a cinnamon pill, vitamin & iron pill.

Yes, bad crank seals can lower compression. 2 strokes have a secret power enhancer designed into them. As the piston rises in the cylinder it creates a vacuum in the crankcase which is what sucks the air into the carb and the fuel/air mixture from the carb, thru the reeds and into the crankcase. As the piston starts down, it compresses the mixture because the reed valve is forced close and as the intake port opens the fuel and air mixture is forced into the cylinder. Hence all 2 stokes are supercharged. If the crank seals are bad and leaking, the mixture in the crankcase will be incorrect and at a lower pressure. Hence the pressure in the cylinder will be lower and that is what you measure during a compression test. The process is also why crankcase "stuffer" boost compression, because they lower the volume in the crankcase and boost the pressure. I had a 99.9 CID V-4, 2 stroke and when I inststalled stuffers behind the vee block reeds, with no other changes, the compression raise 10 psi and upped my speed 1 mph on the radar gun.

[Lunytune]

Hence all 2 stokes are supercharged.

Okay, bring out your little guy with the baseball bat. Dude, this is hard to take for an ole 4 stroker. I guess you know, you're challenging a lot for this ole geezer. Next you'll tell me there is no Santa Clause and Buck Rogers didn't really land on Mars!

Also, what is the "stuffer"?

And where does the DFI get it's air? Is that a reed valve at the bottom? How about oil? And what does the cooling that carb engines provide through air/fuel mixture.

[Bear45-70]

Hence all 2 stokes are supercharged.

Okay, bring out your little guy with the baseball bat. Dude, this is hard to take for an ole 4 stroker. I guess you know, you're challenging a lot for this ole geezer. Next you'll tell me there is no Santa Clause and Buck Rogers didn't really land on Mars!

Also, what is the "stuffer"?

And where does the DFI get it's air? Is that a reed valve at the bottom? How about oil? And what does the cooling that carb engines provide through air/fuel mixture.

A stuffer is just a hard rubber, metal or whatever non-compressible piece that takes up space in the crankcase, there by increasing the compression ratio in the crankcase.

Yes, that is an reed valve at the bottom and that is where the air comes in. There is only air in the crankcase and cylinder so that only unburned air sneaks out the exhaust port before it closes making the EPA * happy.

The oiling is done one of two ways, in the normal way with oil in the fuel at ratios of 100 up to 150 to 1 and also a small amount of oil is dumped in at the throttle bore to lube the crankcase rotating parts. Or an oil injector pumps oil in to the crankcase in much the same way as a 4 stroke does while still using a small amount of oil in th fuel (100 up to 150 to 1 again).

[Lunytune]

You forgot the little guy with the baseball bat.

[Bear45-70]

Do you mean this one? or maybe like this then there is always this and just so you get in on the bashing .