ESE's works engine tuner

[SS90]

I don't think the idea that the copper expanding and tightening up the squish clearance sounds right but...

We know the copper absorbs and transfers heat better so could it be gettting really hot on the inside and acting as a bit of a glowplug?

There is debate over whether it is detonating or not but is the idea worth considering?

Yea, I'm "big enough" to admit when I'm wrong, it's just when you look at the picture of the "copper insert head", after the last meeting...... it looks like detonation damage to me....

In the area if approx. 8 O'clock, and about 11 O'clock

I could be wrong on the expansion concept, happy to admit it if so..... IF it is detonation, it could also be because it is so soft, and as such less detonation resistance (as has been pointed out by others)

Note, sorry about the low res, I use mac, and can magnify in hi res, but if I save it, I can't upload it here, the site doesn't allow TIFF files!

I had to take a picture of my screen with my phone!

[SS90]

Again, my screen has higher res, but that's my reason I say I can see detonation.....

[TZ350]

Again, my screen has higher res, but that's my reason I say I can see detonation.....

Looking at your pictures I can see what you mean. I will take a closer look tonight.

Ok, Its still daylight, Ive put my glasses on and using a good torch I am looking at the piston and head. I have found the marks you can see in the photo's and they turn out to be small impact craters from debris squished between the head and piston. Looking closely I can see the crater and the raised up edges which are polished from contact with the head/piston. Not surprising really as the motor was running nil or very little clearance.

The piston top is rough as it is not machined at all, it is still in its as cast state. The edges are lighter as they have been just touching the head. They have a greasy feel to them from cooked residual oil. The centre of the piston is a grey/light brown and dusty, I can rub it of with my finger leaving a hard brown surface on the piston.

The black areas at the top of the combustion chamber picture are over the exhaust port and looked real bad. At first I thought the copper had overheated as this is what copper looks like when its annealed. But then I found I could wipe it of and it was burnt but not charred oil. The oil stain looked like the (small) stain you like to see on the underside of the piston crown. Different oils they all behave and stain differently, I favour Motel T800 myself but the Team have chosen to use Castrol and I am not that familiar with what it should look like.

It was not detonating but probably was close and certainly has got very hot like you describe. Hot over the exhaust from the short working stroke and therefor hotter exhaust gas and a mixture that could usefully be a little richer.

Close one I reckon. But copper saved the day well maybe.................

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[TZ350]

This is a good read:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

Its about Jante patterns and Port Shape. Can be down loaded and printed.

Here is a little bit of a gold mine:- http://www.2stroke-tuning.nl/media/

Port maps etc, some of its in German.

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[Buckets4Me]

Looking at your pictures I can see what you mean. I will take a closer look tonight.

Ok, Its still daylight, Ive put my glasses on and using a good torch I am looking at the piston and head. I have found the marks you can see in the photo's and they turn out to be small impact craters from derbs squished between the head and piston. Not suprising realy as there the motor was running nill or very little clearance.


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it's lucky that you run a good air filter then isn't it

I found an answer to all your problems

first you hit it with a big hammer
if that dosent work hit it with a bigger hammer
if that dosent work it's got to be an electrical fault

any way back to it. Will ring John very soon

[TZ350]

it's lucky that you run a good air filter then isn't it

Air filter, whats that ?????????

I found an answer to all your problems

first you hit it with a big hammer
if that dosent work hit it with a bigger hammer
if that dosent work it's got to be an electrical fault

Thats right! it works for me every time.

any way back to it. Will ring John very soon

That would be great, as, maybe the weekend? I will bring all the team bikes so we can compair.

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[SS90]

Looking at your pictures I can see what you mean. I will take a closer look tonight.

Ok, Its still daylight, Ive put my glasses on and using a good torch I am looking at the piston and head. I have found the marks you can see in the photo's and they turn out to be small impact craters from debris squished between the head and piston. Looking closely I can see the crater and the raised up edges which are polished from contact with the head/piston. Not surprising really as the motor was running nil or very little clearance.

The piston top is rough as it is not machined at all, it is still in its as cast state. The edges are lighter as they have been just touching the head. They have a greasy feel to them from cooked residual oil. The centre of the piston is a grey/light brown and dusty, I can rub it of with my finger leaving a hard brown surface on the piston.

The black areas at the top of the combustion chamber picture are over the exhaust port and looked real bad. At first I thought the copper had overheated as this is what copper looks like when its annealed. But then I found I could wipe it of and it was burnt but not charred oil. The oil stain looked like the (small) stain you like to see on the underside of the piston crown. Different oils they all behave and stain differently, I favour Motel T800 myself but the Team have chosen to use Castrol and I am not that familiar with what it should look like.

It was not detonating but probably was close and certainly has got very hot like you describe. Hot over the exhaust from the short working stroke and therefor hotter exhaust gas and a mixture that could usefully be a little richer.

Close one I reckon. But copper saved the day well maybe.................

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O.K then,

Perhaps you need to look at hardening the copper (similar process to annealing)..... the Egyptians where hardening copper axes "back in the day" (not sure what their buckets where made of though)

You can get a cylinder head temp sensor unit that goes under your plug (like the det counter ones), and my experience is that they work well, Kart shops normally sell them.

Would be useful in future dyno tests.

[SS90]

Also, you wrote (quote).... "It was not detonating but probably was close and certainly has got very hot like you describe. Hot over the exhaust from the short working stroke and therefor hotter exhaust gas and a mixture that could usefully be a little richer."

The exhaust port area of the crown certainly looks hotter than previous pictures (same working stroke, same exhaust, same exhaust port areas)... what do you attribute that to?

I don't think a little richer would solve this particular problem.(although, just looking at the colour it could use a slightly bigger main jet) along those liknes, I am of the opinion that reducing your "static retard" would assist dramatically.

That would help, but certainly not eliminate the problem. I believe that would also have a flow on effect of reducing overall combustion chamber temperature as well.

Certainly only one piece of the puzzle.

[SS90]

Are the "holes" in the head from debris ingression as well?

[TZ350]

Are the "holes" in the head from debris ingression as well?

I didn't actually hold the head over the piston and match the marks up but I expect that a mark on the piston would have a matching mark on the head.

Also the piston has a small dish in it and the squish band flat area is only 4mm wide. You can see the flat outer edge which is lighter in colour and the dish is a darker grey.

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[TZ350]

Gordon Blair, "The Basic Design of Two Stroke Engines" 41MB PDF, it takes a while to load:-

http://sauvegarde.cerbernetic.com/Ma...1560910089.pdf

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[craisin]

sounds like the piston crown and head are taking on heat thru irregularities on their surfaces.
And I am sure back there ^^^^^ somebody has mentioned that polishing these surfaces is a good move

[SS90]

I didn't actually hold the head over the piston and match the marks up but I expect that a mark on the piston would have a matching mark on the head.

Also the piston has a small dish in it and the squish band flat area is only 4mm wide. You can see the flat outer edge which is lighter in colour and the dish is a darker grey.

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Sorry, didn't quite make my question clear!

What I meant to say, was there are TWO areas on the cylinder head with different looking conditions on them, and, best as I can see (and from what you write) there is only ONE area with Marks on the piston.

Where as, on the combustion chamber, there are TWO clear areas (It's logical to suggest that one is the exhaust port area!)

So, my experience would suggest IF this is the case, then while one area of damage can be attributed to "small hitch hikers",(the area with marks on the piston, and the head) then the area with only marks on the head (not corresponding with any marks on the piston), would indicated something quite different.

Especially considering the fact that copper has such low detonation induced damage resistance (somewhat lower than the hi-silicone piston)

Thanks to the Missus, I have learned how to convert the TIFF files to JPEG (just learning what everyone else knows there I guess)

And I hope they are as clear when I post them.

Teezee, I may be seeming to come off as pedantic, but I have a personal and professional interest here!

I'm just questioning the concept so I can learn about it's suitabilty!

IF it is as I suspect (going only by photo's), than there is a good chance that the copper is too soft (and as such, the detonation resistance is too low) for the job.

I respectfully suggest that detonation on a copper surface would look different to detonation on an aluminium (piston/aluminium head) surface.

This idea gains a little weight (in my eyes) when you add into the equation that "the piston is touching the head".... perfect environment for detonation I would suggest!

The first picture some of the marks could be attributed to "particles" being crushed (normally, in my experience showing a uneven "star" type shape, (much like a sandfly on your visor)

Not all the damage has the same appearance though, as some are "almost perfect craters"

I have seen a situation where a piston was used that was too low in detonation resistance (quite the opposite of this engine, as I believe the insert is now the "weak link"), and the detonation showed itself as "tiny little (almost) perfect "craters".

Exactly like what I see in some parts of pic 1, and all of pic 2

I surmise this type of detonation is indicative of contrasting detonation resistant materials.

If the "copper lined" head is indeed causing the cylinder head temperature to decrease, perhaps you could just lower the compression ratio (and stop the piston touching the head....ahem...) and this would stop the detonation, and still have the effect of keeping the combustion chamber cooler (even more so with the lower compression)

I am starting to think that if it is set up correctly (find the right compression ratio that is suitable for the situation)
then there is a chance that there is a tangible benefit to this concept.

Either that, or find a way to make the copper more detonation resistant.

Starting to like the idea though.....

Oh yea, the reason I surmised the copper was expanding at taking up squish clearance was I think it is safe to assume that Teezee would not assemble an engine that would have the piston touching the head!

[craisin]

smooth surfaces = less cling-ons or hitch hikers.

[TZ350]

Back to the shed tonight with glasses, torch and magnifying glass.

Wenever will I get time to read: Gordon Blair,

"The Basic Design of Two Stroke Engines" 41MB PDF, it takes a while to load:-

http://sauvegarde.cerbernetic.com/Ma...1560910089.pdf


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