How do rings go bad from just sitting

[TLH]

Ok hereÔÇÖs the deal, I have not been this mad in about 10 years, I'm a motorsports guy with lots of background in all kinds of motorsports from off road to drag racing.

I have an 1986 SPREE That I used as a pit bike for my drag car, When I bought a house and had a kid, I had to put drag racing on the back burner, spring forward 12 years and we are going drag racing once again, so I get the spree out drain out old gas, remove carb and clean (and yes I know about the small holes that always get plugged up), Put some mm oil down the intake and cyl. It spun over fine.

Keep in mind it ran great when I parked it 12 years ago
I put the carb back on and tried to start it, it pops but wont start, so I start to check to see why... It has fuel, it has spark, it has.... oh wait 60psi compression * OVER!

So how do rings go bad from just sitting, this is a new one too me, at first I want to blame cheap Japan stuff, but I have a Honda 200 quad that we use also and it started right up after the long wait to go back into service.

So I think well maybe the rings are gummed up from sitting, so I pull the whole engine out and put it on my work bench (tired of bending over to work on it ) So I pull the head and it looks like it has a small head gasket leak on the ex. side of the head, so I think yeah thatÔÇÖs got to be the source of the low compression, but I still took the cyl. off to check the rings everything was clean and free, so I'm thinking for sure that leak has to be the source of the low compression, I put it all back together and itÔÇÖs still the same 60 psi.

So at this point I'm so * off and tired of working on this thing, That if I can not get a good answer about how rings can just go bad from sitting, I'm going to tie a long rope to it and put it in the back of my truck, (and with someone to take video) GET UP TO ABOUT 40 MPH AND PUSH IT OUT. And watch it fly apart.

T.

[Bear45-70]

It happens because you don't winterize/store the engine properly. The engine needs to be run on extra 2 stroke oil and then storage oil needs to be sprayed into the carb while the engine is still running and then stall the engine with the storage oil. This coats all the internal parts with the storage oil that stays on the parts. Two stroke oil has a problem staying on parts for much more than a month before gravity makes it slide down to the bottom of the engine. After the oil in gone, things rust and corrode and can even freeze together. What probably happened was the ring stuck to the cylinder wall and when you cranked the engine they popped loose but now do not seal to the cylinder walls anymore. It is gonna require that the jug needs honing and replacing the rings. But this is an operator error issue. S stokes are not 4 strokes and will not tolerate abuse like 4 strokes will.

[TLH]

So are you saying that 2 strokes use a different type of ring material than a 4 stroke.?

What is it that makes a 2 stroke not as resilient as a 4 stroke.

I'm starting to charge video cam. batt.

[Spreetard]

i weep for the welfare of your poor spree. i'll laugh at the video, but be * at the sheer wastefulness of the whole fiasco . you should just give it to me, so it can have a warm, loving home.

[Wheelman-111]

Greetings:
Yo Spreetard! Back off with the orphan scooter thing. That's MY schtick!

[elitedio]

Ok hereÔÇÖs the deal, I have not been this mad in about 10 years, I'm a motorsports guy with lots of background in all kinds of motorsports from off road to drag racing.

I have an 1986 SPREE ..............
So at this point I'm so * off and tired of working on this thing, That if I can not get a good answer about how rings can just go bad from sitting, I'm going to tie a long rope to it and put it in the back of my truck, (and with someone to take video) GET UP TO ABOUT 40 MPH AND PUSH IT OUT. And watch it fly apart.

T.

60 psi isn't great but probably enough to make it run. Particularly since your engine is cold. I bet you still have some gump in the carb. Have you tried a bit of raw gas or starter fluid in it with a new plug? I fiigure that if the static compression ratio may be 12:1 and with a 2 stroke half of the stroke is lost to having open ports. Giving 6:1. How are your bottom end crank seals?

Still it would be nice to see you push out the scoot from the back of your truck, make sure your rope isnt looped around your foot. Now that would make a unique video.

[Clivester]

How are your bottom end crank seals?

I was just about to suggest that the seals could have dried out and age-hardened, rather than the rings being the problem.

[TLH]

Ok hereÔÇÖs the deal, I have not been this mad in about 10 years, I'm a motorsports guy with lots of background in all kinds of motorsports from off road to drag racing.

I have an 1986 SPREE ..............
So at this point I'm so * off and tired of working on this thing, That if I can not get a good answer about how rings can just go bad from sitting, I'm going to tie a long rope to it and put it in the back of my truck, (and with someone to take video) GET UP TO ABOUT 40 MPH AND PUSH IT OUT. And watch it fly apart.

T.

60 psi isn't great but probably enough to make it run. Particularly since your engine is cold. I bet you still have some gump in the carb. Have you tried a bit of raw gas or starter fluid in it with a new plug? I fiigure that if the static compression ratio may be 12:1 and with a 2 stroke half of the stroke is lost to having open ports. Giving 6:1. How are your bottom end crank seals?

Still it would be nice to see you push out the scoot from the back of your truck, make sure your rope isnt looped around your foot. Now that would make a unique video.

Ok so now we are getting some tech, I know that bad seals can greatly affect a running engine because bad seals would cause a lean condition/vacuum leak, but can it affect cranking compression?

I did try gas and starter fluid and no luck, carb is clean bystarter works. compression comes up to 105 when I put oil in the spark plug hole, still sounds like bad rings huh?, but still why?


Thanks for a reply with some tech, minis the attitude.....

[Clivester]

Ok so now we are getting some tech, I know that bad seals can greatly affect a running engine because bad seals would cause a lean condition/vacuum leak, but can it affect cranking compression?

The upward stoke of the piston causes vacuum in the crankcase to draw in air/fuel. The downward stroke then compresses the mixture to forced it through the transfer port into the cylinder area ready to be ignited toward the top of the upward stroke (which produces the measured compression). If a leaky crankcase fails to produce sufficient vacuum to draw in fuel/air, or causes loss of air volume during crankcase compression, there is less air to be passed into the cylinder. Less air means less pressure and therefore lower compression.

Bad reed valves can cause this too.

[TLH]

That makes sense, I will look into the seals, that makes more sense than the rings going bad just from sitting.

T.

[Lunytune]

That makes sense, I will look into the seals, that makes more sense than the rings going bad just from sitting.
T.

Rings don't go bad. I've seen guys revive car motors that were froze up while in non-use/storage, by squirting penetrating oil in the plug hole, let it set overnight and start working the crankshaft until it comes loose. With everything serviced, it would fire up and run. It would smoke for a while but eventually clean up.

[elitedio]

From the first post this thread should have been moved to the off topic area as there is not much technical content needed to push an innocent scooter off the back of the truck.

What might be fun is to tie the rope to the two scooter and do a tug of war. Might motivate the original poster to fix his spree or just continue his embarrassment of acting quite silly.

The content here is like looking at a car accident, you don't want to see it but it difficult to ignore.

[mousewheels]

The content here is like looking at a car accident, you don't want to see it but it difficult to ignore

Content is in General Chit-Chat under Broken Rules Thread, but it's likely to go away. Gent's keep your posts out of the oil pan.

[Arnadanoob]

Being in Hawaii we're not experts at storing bikes seasonally however I would think along the lines of how corrosion and other factors may contribute to changing the properties of the bore/piston/rings over an extended time. Engine oil can help but only until the oil can maintain a film on the parts. Some oils (and fuels) turn acidic over time and can eat away at the metal or leave deposits/coatings on delicate parts like the carb/fuel tank/petcock. Aluminum doesn't exactly rust like iron but it does oxidize and the end result is similar to rust.

I recently helped restore an old dirt bike of my neighbors and it never ran for at least 10 years. Even hand priming/turning the engine over wasn't enough to get past the fact that it was sort of seized. After investing some time into using different types of lubricants and heating up certain parts, we had to disassemble the bore/piston and gave the cylinder a nice repolishing (a true honing wasn't necessary) but the varnish from the old fuel and subpar oil left residue bad enough to alter the tolerances. The piston/rings had to be cleaned/soaked in a strong solvent overnight to get rid of the buildup but after reassembly and a new spark plug it fired right up with a ton of smoke and ran very strong after it warmed up.

[Wheelman-111]

Greetings:

Arnadanoob makes some excellent points. Thanks for that.

Remember too that the ring/bore wall seal is a dynamic process. We tend to think of the bore and piston diameters as fixed quantities, but there is some dimensional expansion of both when the engine heats up. This is one reason why pistons fit sort of "loosely" in their bores. The factor isn't big - like .005 or less - but it is important to leave room for a film of oil. It's another reason why rings aren't solid circles, but have a gap that is carefully calculated. The "spring-loaded" contact between the rings and the bore takes up the slack.

If the rings become glued to the piston by corrosion, hydrocarbon resins, and immobility, remember that the bore is fully contracted as it sits there in a cold storage shed. Remember also that there's no such thing as a perfect circle, or a perfect cylinder. Wherever the piston rings lie in the bore may be out of round, or the bore may be of a smaller dimension than it is above or below. If the rings can't "spring" out when you finally fire up that bad boy, they will lose contact - therefore compression - with the cylinder walls.

The extent to which rings can get "stuck" became clear to me when I attempted to disassemble "Timmy's" slug. Yep, broke 'em both. What I should have done is to soak the piston upside down in a jar of acetone before attempting. Next time I'll know better.