ESE's works engine tuner

[wobbly]

Using the pumping pressure for diagnosis is fine.
Saying - its got 220psi, so is perfect for Avgas is bullshit.
I have seen a variation of 30 psi in 200 depending upon how wet the bore is.
Try varying the com up or down by 15%,thats instant blowup Vs a piece of shit.
Then factor in the issue of varying pressure depending upon the length/dia of hose between different gauges - a flawed test device of the first order.

[TZ350]

Saying - its got 220psi, so is perfect for Avgas is bullshit.

Do people say that? .... where? ... not here surely.

[TZ350]

A measuring tool is just a tool.

And one has to apply some intelligence in how you use it and what you infer from it.

- a flawed test device of the first order.

There is no way of making the perfect measurement, every test and measurement device ever known to man is flawed in its own way. Its just a question of how useful the measurement that you can make with it is.

I have seen a variation of 30 psi in 200 depending upon how wet the bore is.

You can probably expect a "Hot" test to reflect the wetness (sealing) of a running motor.

On a four stroke, oil is added to a cylinder that is down on compression as an aid to determining if the compression leak is in the rings or valves, the oil helps seal worn rings. And that probably adds weight to the notion that more oil makes more power in a 2-Stroke.

Then factor in the issue of varying pressure depending upon the length/dia of hose between different gauges

There is a valve in the spark plug adapter fitting so the length of the hose does not matter as the hoses internal pressure is pumped up. And after a few cranking cycles the pressure inside the hose approaches the peak cranking pressure inside the cylinder.



The errors here are the accuracy of the gauge itself and the pressure required to open the valve.



There is another valve here to release the pressure from the hose.



The biggest problem I can see with making good measurements, is the difference in volume between the pressure gauges adaptor and the spark plug.

On a big V8 that might not be a significant problem but a 1/2" adaptor on a 50cc 2-stroke engine that uses a 3/4" reach plug like an RG50 now that would make a big change to the measured pumping pressure.

The first picture shows a gauge with different adaptors for this problem.

Try varying the com up or down by 15% ...

So ... yes on our little bikes using a pressure gauge for setting the com ratio would be a disaster.

CCing the assembled engine is the correct way to vary the com ratio, a compression tester is a diagnostic tool. Used properly it can give you some re assurance that everything is OK, and that you havn't made some gross mistake CCing the cylinder/head.

[F5 Dave]

I've had retarded conversations with people about using gauges for tuning, but they want to cling onto the measuring tool in their hand because they get numbers. Who cares if its wrong or right? There's Numbers!!



for Giggles a few years ago having rebuilt my dirtbike I thought I'd do a before & after rebuild. Then I skimmed the head to correct crazy squish, got the compression ratio too high (as I'd expected) then took some out of the chamber till I was happy. - Obviously measured with a Burette

the Gauge numbers were all around 199, 198 etc near the end, but actually went up a number when I had measured that I'd taken metal enough to lower the compression about 2 full ratio numbers. Clearly the gauge was bollocks (despite being German) as a tuning tool & overly influenced by oil kicked out of the cases or whatever. To even measure wear over time (which was my only interest) might be distorted.

A leakdown test may (I've never used one except my low pressure - piston at bottom for case leak) be better for checking wear, but why not just pull the top & measure the ring? I spoke to a kart tuner the other day who was all into 'ring seal'. Seemed a bit elusive, I've only just measured ring gap & that seems consistent with power loss, but what do I know, maybe I'm missing something.

[bucketracer]

Old style dropper Burette, we have several, the taps tend to get stuck if left and they are broken easily.



An easier to use Burette for jobs like CC ing combustion chambers, ESE has one. TeeZee swears its the ultimate.



Then there is the quick and dirty 3 - 5 - 10 CC plastic syringes which are pretty cheap from your local Chemist.

Then top it off with a compression test.

Compression testers seem to generate as much emotion as discussing the right type of oil to use did.

I've had retarded conversations with people about using gauges for tuning, but they want to cling onto the measuring tool in their hand because they get numbers. Who cares if its wrong or right? There's Numbers!!

Yes, comfort in numbers, a bit like copying down all the digits from a calculator in the mistaken belief that makes the result more accurate.

[husaberg]

Compression testers seem to generate as much emotion as discussing the right type of oil to use did.

Tooo Right I am still in Therapy from that one myself.
But somehow i are starting to suspect my psychiatrist must fancy my Mum?
because he always goes on and on about banging her
Gee what what Freud say about that? And whats up with this guys Cigar?
gee what would he say about that, Plus why do i like two strokes

[SwePatrick]

Attachment 268228 Attachment 268223

I am taking another look at the plenum, tonight I Devcon puttied up the inside of the chamber so that any fuel dropout runs to a collection point and can be pumped away by the pulse pump. Hopefully this will get over the unstable fuel mixture issues with the puddling problem we had before.

At the moment the chamber is 1L and EngMod suggests 2L would be better so a bit of work to be done there. For anyone interested in the math, 2L makes the plenum 16 times the size of the engine.

Cool.. but why not just build a pipe like rodeltrack from carb to inlet tract?
It lets almost all fuel that falls out to be sucked in into the engine, then you can tune the plenum pulse with different opening at top of the 'tube'.

it dampens out the pulses and letting the carb work with more even flow but still almost all fuel into engine.
More easily to tune.

Rgds
Patrick

[RAW]

This ones for Frits
On the pit lane forum you discussed the joining of the intakes upon a twin cylinder reed valve engine, the conection being between the 2 carbs and the reeds of each cylinder, how would this in your opinion function in a twin with rotary discs, would you explain the pros and cons of such a set up for each engine please

[TZ350]

... but why not just build a pipe like rodeltrack from carb to inlet tract? It lets almost all fuel that falls out to be sucked in into the engine, then you can tune the plenum pulse with different opening at top of the 'tube'. It dampens out the pulses and letting the carb work with more even flow but still almost all fuel into engine.

Hi Patrick sounds good but I don't understand what a "rodeltrack" is or looks like.

I guess its like an inlet tract from carb to crankcase inside the plenum with the top of the inlet tract cut open so it vents to the plenum but guides the fuel and oil into the engine.

Do you have a picture of what you mean?

[husaberg]

Maybe Trombone Exhaust? or Rod and Track in Google translate?

[teriks]

Rodel and bobsleigh use the same tracks/runs, see video below.
Looks like you can have fun even without two-strokes

[F5 Dave]

This ones for Frits
On the pit lane forum you discussed the joining of the intakes upon a twin cylinder reed valve engine, the conection being between the 2 carbs and the reeds of each cylinder, how would this in your opinion function in a twin with rotary discs, would you explain the pros and cons of such a set up for each engine please

I think you'll find hes on holiday mate. These Europeans & thier smug opposite hemisphere climates. Oh well at least its not raining here today.

[2T Institute]

I think you'll find hes on holiday mate. These Europeans & thier smug opposite hemisphere climates. Oh well at least its not raining here today.

Maybe Vrouw Overmars carried out her threat ! (but we all get those threats don't we )

[F5 Dave]

Its the middle of summer. "Shall we go on holiday?" Doesn't sound like a threat, - sounds like a treat!


Probably going to be raining at the track sunday when I try my new engine. Dumb winter.
[sigh]

[RAW]

Maybe Vrouw Overmars carried out her threat ! (but we all get those threats don't we )

Yeh thats rite, good luck to him ( Frits & partner ) hope your enjoying yourself, I'm sure he is trying to sneak a peek at the forum world given half a chance

Just think of the hundreds of forum questions about the world he now has a chance to answer, this is the first time I don't wish to be in your shoes Frits