Micro 12VDC Generator with a Cox .049 Sure Start Diesel Engine

robot797 wrote:then it is still tapered



the ring does not stop the piston

Sorry. The piston touches the rim when the piston stops.

Maybe we have different cylinders.

i was talking about the head gasket

and does one know were the metal rings are sold?

robot797 wrote:i was talking about the head gasket

and does one know were the metal rings are sold?

The rim is built into the cylinder.

The Copper gaskeys are sold by Cox. You personally posted the link.

I would be happy to use these to lift the Teflon gasket up. Slightly enlarges the chamber which would probably be the same difference. However, may protect the Teflon gasket from touching the piston.

to claryfie (maybe we are talking about somthing the same)

when a piston get stucks in the top it is called a taperd cylinder

there is no special edge or somthing to stop it
just a taper (the walls of the cylinder come closer to eachother on the top)

this taper is also the reason why it needs running in

robot797 wrote:i was talking about the head gasket

and does one know were the metal rings are sold?

The rim is built into the cylinder.

The Copper gaskeys are sold by Cox. You personally posted the link.

I would be happy to use these to lift the Teflon gasket up. Slightly enlarges the chamber which would probably be the same difference. However, may protect the Teflon gasket from touching the piston.

lol

there was a exact repeat of one of you last posts

robot797 wrote:to claryfie (maybe we are talking about somthing the same)

when a piston get stucks in the top it is called a taperd cylinder

there is no special edge or somthing to stop it
just a taper (the walls of the cylinder come closer to eachother on the top)

this taper is also the reason why it needs running in

As I have said : there is no tapper, no shrinkage, no enlargements no deformation. Just a rim which stops the movement.

When the engine works, the piston cannot reach the rim because the crankshaft and the piston rod do not extend so far away. When the piston is not reset, the compression and combustion prevent the cylinder to touch the rim. Whe the engine misses or during start up, at low compressions the piston may be thrown onto the rim which would create vibrations on the crank pin.

The same applies when the piston is down. Non reset piston will wiggle thuscreate vibrations on the pin.

Vibrations degrade the pin and cause metal fatigue which is not good for the pin which is extremely thin.

that rim should not exist
maybe some of the old people here can explain it

but i have never seen a rim on my cox engines

not on my old medalion
not on my sure starts

i have seen tapers
were it get stuck at the top (the piston is on the top op the cylinder)

but i have never seen a rim

Surfer_kris wrote:The head design with a Teflon gasket is not a good one, as you too have found out the hard way. You can fix this by replacing the teflon gasket/disc with a metal one, thin sheet of brass works fine.

The are other diesel heads for cox .049 with much better designs, for instance the ones from RJL which are sold by Mecoa.

Here is what they look like from the outside;

Thanks. The information for a third party head preferred by you and, probably, by many in the forum is great.

However, I like the ingenious idea of Teflon gasket protection which is the best feature of the engine. The problem is not the idea nor the design but the manufacturing and material of the Teflon gasket, most likely carried out in China or Hong Kong.

As a gross generalisation, Teflon is not a good material. Bad Teflon is much worst.

I have read of the thin metal replacements, people usually cite thin Brass or Copper, but these defy the purpose.

However, I think I have some 0.5mm Brass or Bronze, fotgot, and I can send raw metal or grin one or two for whoever wants. I got the metal for guitar picks.

Otherwise, I have lots of 1mm Aluminium.

robot797 wrote:that rim should not exist
maybe some of the old people here can explain it

but i have never seen a rim on my cox engines

not on my old medalion
not on my sure starts

i have seen tapers
were it get stuck at the top (the piston is on the top op the cylinder)

but i have never seen a rim

Again, even the brand new ones get stopped by the rim.

Instead of continueing the " I say, you say " word exchange, please contact support at CoxEngines.ca and you will receive a thrustworthy answer of your question.

robot797 wrote:lol

there was a exact repeat of one of you last posts

I do not think the standardised forum software available to most forums has been designed very well, hence posting multiples.

In case you want a circle of metal instead of your Teflon, I can make you some, just say so. Choose the thickness of the circle between 0.5mm and 3mm.

Thin circles can be used with the counterpiston. Thick, without.

Instead of Teflon, Cox was supposed to use thin Aluminium to break or fold or shatter at high pressures. Other metals and alloys welcome. The more brittle the better.

the counterpiston is needed for operation
it pushes the disk down to make the compression chimer smaller

without it it wont do anything

and for the metal disk
o have 0.1mm copper sheets i only need a punch to make 13mm holes

my hands are not good enough to use sicors to cut some disks

robot797 wrote:the counterpiston is needed for operation
it pushes the disk down to make the compression chimer smaller

without it it wont do anything

and for the metal disk
o have 0.1mm copper sheets i only need a punch to make 13mm holes

my hands are not good enough to use sicors to cut some disks

Very thick circle can be pushed directly by the compression screw. Must not be tight to allow compression to escape. Teflon is better in this sense, because the force of the screw defines the pressure of the Teflon over the rim and the Teflon will always be on the rim and not moving for most high compressions.

Also, I forgot, when a circle is made of thin brittle metal, whe shatterred, the metal pieces would go into the cylinder and scratch. This is why Teflon is better, sorry.

For non shattering circles, no, you should not cut 1mmAluminium with sheers. I can cut rough piece with bolt cutters and then grind the piece on a grinder to make the circle with the necessary radius. Then, I would put on the rim, take out, file by a manual file then measure again, then file again, etcetera.

Just say you want and I will do.

However, I will continue to use Teflon for protection. Even thinned or punched Teflon gasket in the middle works with the counter piston on top.

so you think if i were to place a solid metal disk under the head without a sub piston i can still adjust the compreeion


the screw only goes halfway and the rest of the room is filled with the sub piston

the disk must be thin and flexiable
so that it can be adjusted
if it were thick yea it would snap into tiny peaces

but a thin sheet just tears like the teflon does


this is not ment to sound harsh

but i am kind of confused with how you think tings work

robot797 wrote:

so you think if i were to place a solid metal disk under the head without a sub piston i can still adjust the compreeion


the screw only goes halfway and the rest of the room is filled with the sub piston

the disk must be thin and flexiable
so that it can be adjusted
if it were thick yea it would snap into tiny peaces

but a thin sheet just tears like the teflon does


this is not ment to sound harsh

but i am kind of confused with how you think tings work

Thick circle has only one disadvantage and will work : when the compression screw is untightened, there is no much room for the compression to escape. No other problem.

Because the counter piston is with a lower radius, the compression can escape between the cylinder walls and the counterpiston. This is the only advantage paid for with strength and stability.

Thick and thin will work. Choose what you want and I will make you some.

All you need to do is to think what happens. The more you think from different angles the more things you will find on what happens.

And no, counter piston is not necessary but is better for a better compression control.

you know the counter piston does not touch the fluel

the disk (be it teflon or metal)

seals the counter piston from the combustion chamber

the counter piston ic critical in this design
it presses the disk down to create a smaller combustion chamber

if it were just a screw it would punsh the teflon and the engine would stop running

sorry to say but only the rjl does not need a sisk becaus there the sub piston has a O ring to make compression

robot797 wrote:you know the counter piston does not touch the fluel

the disk (be it teflon or metal)

seals the counter piston from the combustion chamber

the counter piston ic critical in this design
it presses the disk down to create a smaller combustion chamber

if it were just a screw it would punsh the teflon and the engine would stop running

Compression and thus fuel go around the Teflon disk.

Thick or thic circle, compression will go between the circle and the walls.

You do not need to drill holes in the circle.

Can work without the counter piston. Thin circle with a counter piston gives higher sensitivity of compression screw controo.

IT CANT WORK WITHOUT THE COUNTER PISTON

every bit of fuel is topped by the disk be it teflon or metal

the counter piston just applies an even pressure to the disk so that it does not get punctured

if there is no counter piston you cant set the ignition timing
and if you cant set that it wont run

the counter piston is not ment to seal
it needs to bounce and flop with every stroke

you know what
i am gonna ruin my last teflon disk for you
i am gonna start my generator without the counter piston
and you will see it cant start
and if i can find some i will even cut a few cans to make thick disks
and it would still prove my point

robot797 wrote:IT CANT WORK WITHOUT THE COUNTER PISTON

every bit of fuel is topped by the disk be it teflon or metal

the counter piston just applies an even pressure to the disk so that it does not get punctured

if there is no counter piston you cant set the ignition timing
and if you cant set that it wont run

the counter piston is not ment to seal
it needs to bounce and flop with every stroke

Can. Metal cannot be used as a membrane to reduce or enlarge the chamber. Metal can only be used to allow compression to move around the piece or not or what amount.

Reduction of the chamber means also reduction of the amount of fuel and air and this defies the purpose of higher compression.

Membrane effect is not welcome but parasitic.

Dome down position is preferred for strength not for membraning.

Thick circle without a hole directly controlled by the compression screw will work. The control sensitivity may be lower. More has to be undone to reduce compression.

No, counter piston is not necessary. Counter piston, because of lower radius and loose fit, does not stop the compression while thick circle does. Hence, thin circle and counter piston will allow more compression to leak through when the screw is untightenned to the same position.

Again, counter piston is for convenience and not for principle.

i am gonna pull myself away from this

becaus you have the operation of these diesel engines all wrong

i will be back tomorrow
and try to explain it in a easery way

robot797 wrote:you know what
i am gonna ruin my last teflon disk for you
i am gonna start my generator without the counter piston
and you will see it cant start
and if i can find some i will even cut a few cans to make thick disks
and it would still prove my point

Teflon disk cannot be controlled well without the counter piston and this is the only reason why may not work. Also, the hot screw would punch the Teflon. Better save your Teflon gasket.

Putting a few thin circles instead of one thick will not give you precision. However, you may try. Will no hurt and will start, maybe at different settings. You need to cut a lot of circles because cans are very thin. You need thickness roughly equal to the thickness of the piston and the thickness of the Teflon gasked combined. They have to be very accurate and strong.

I nternet cites people replace the Teflon gasket with Brass. I am not aware of any Brass spring effect, i. e. I think Brass has memory as well as Copper. Once bent, does not go back.

I will be happy to see the result with thick Aluminium and no counter piston. Make sure some of the leafs of Aluminium do not penetrate lower than the rim.

Best do not do.