ESE's works engine tuner

[pete376403]

This one runs a surface fire plug, out of a Rotary, 10 heat range, E85 fuel.

Surface gap plug was standard on my '72 F9, supposedly not as suceptible to fouling as a regular plug. It still did though.

[Gradella23]

Originally surface discharge plugs were used commercially in outboards when first CDI became available.
They needed a high discharge voltage as the effective spark gap was large from the center electrode out to the body.
Plug technology has advanced hugely since then with rare earth center and ground fine wire electrodes , that require less voltage than "ordinary " plugs and now we have no issues with fouling.
I can see no logic in using these nowdays in any specific application where they might be an advantage.

Surface gap plugs were of course OE on the Kawasaki Mach 3. Which had I think one of the first CDI systems. Word at the time was that the higher discharge voltage eroded conventional plugs and shortened their service life. Surface gap plugs don't change the gap with age and use.

As Wob says, no reason to use them now. Technology has moved on.

thanks.
so no advantage at all coming from the design itself, say a cleaner combustion chamber with no "shadow" from the electrode.

[lohring]

I had an idea to reform the combustion chamber of our 26 cc restricted engine class to lower the chamber volume. We were only allowed to remove material for modifications, but there were no restrictions on spark plug design. I suggested a plug with a large base that created a toroidal combustion chamber. My design used a surface discharge end. My friend, the late Jim Allen, liked the surface discharge idea and modified some conventional plugs. He was already running a toroidal head button in his unrestricted design 26 cc engine. I don't believe he found any advantage over conventional plugs in his toroidal chamber. Below are pictures of my idea and Jim's actual plug.

Lohring Miller

[wobbly]

Regarding the spark gap " shadow " produced with a ground strap. I did dyno tests to prove or disprove the idea of indexing the plug , that rumour had it was an advantage.
In a box of 4 I by chance found two R 7376 -10.5 plugs that indexed 180* opposite each other.
One had the gap facing the Exhaust port the other facing the boost port.
The one with the unmasked gap facing the Exhaust I convinced myself after multiple back to backs was better , by maybe a 1/10 or 2/10 Hp - the width of the graph lines , probably not within the limits of the dyno read accuracy.
I still do it today , just because I did the test and it makes me feel clever , even though Frits has proved otherwise more than once.

[skako]

Here I slightly improved the previous version of the calculation for the suction flow into the crankcase of the 2T engine. The calculation is carried out according to the work of Dr. Hoffman. The calculation method is multiple iterative, conservative and preserves the flow of mass and energy through the orefice. I studying for further.

[Frits Overmars]

Regarding the spark gap " shadow " produced with a ground strap...The one with the unmasked gap facing the Exhaust I convinced myself after multiple back to backs was better... I still do it today , just because I did the test and it makes me feel clever , even though Frits has proved otherwise more than once.

That was never my intention mate. Anyway, two-strokes can make all of us look stupid.

[philou]

a French ignition manufacturer cuts or drill the ground electrode of its spark plugs.

it indicates that by testing the spark plug under pressure of 10 bars. the sparks go from the electrode to the base.

it indicates having a better revving without the ground electrode.

its ignitions are at fixed advance. according to him, the variable is useless. Turbulence velocity with rpm has the same effect

[skako]

Here are some more interesting diagrams for analyzing waves and the charging effect. I was looking for the length of the suction pipe that gives the maximum filling of the crankcase. Everything else is unchanged. Crankcase temperature 358K, intake pipe temperature 280K, ambient temperature 293K, atmospheric pressure 1 bar.

[wobbly]

Skako , I see a ref to the inlet as 118* what does this mean ie on your analysis where does the port open and close in relation to TDC .
Is that the pink line shown as IC around 59* before and after .

[skako]

Skako , I see a ref to the inlet as 118* what does this mean ie on your analysis where does the port open and close in relation to TDC .
Is that the pink line shown as IC around 59* before and after .

Yes, it's a pink line. It is a symmetrical intake. The intake port opens 59 degrees before TDC and closes 59 degrees after TDC. The total open time is thus 59° + 59° = 118°. This is the classic suction method for many older mopeds such as the Tomos.

[TZ350]

I'll be real interested to hear how that goes, even using a laser the melting temp difference is huge...

Ok. Welded Tungsten slugs.

The heat shrink on the rod was to protect the rod from being an accidental earth and causing a welding flash over and pitting of the bigend.

Next step, check the crank is still straight then re assembly.

[husaberg]

Ok. Welded Tungsten slugs.

The heat shrink on the rod was to protect the rod from being an accidental earth and causing a welding flash over and pitting of the bigend.

Next step, check the crank is still straight then re assembly.

Does that have a speedy sleeve on the seal surface ?

[TZ350]

No speedy sleeve. This is the drive side. The drive gear has the seal surface for the rotary valve covers oil seal to run on.

[RomeuPT]

Hello again

Long time no posting.

I was having a conversation the other day with a friend and he came in conversation that low torque engines like bigger front sproket, this is not about the transmission ratio. He says that bigger cc bikes with high torque like smaller sproket, but low cc with high rpm big front sproket. He showed me a file where it talks about this, but its in Portuguese.

Then I research around some fast 125cc bikes and the sprokets tend to be from 17 to 20 so I got a bit curious about it.

Cheers

[F5 Dave]

Sounds like he is all torque.