ESE's works engine tuner

[TZ350]

More progress from Alex at Two Stroke Stuffing.

[TZ350]

Reading spark plugs. 2Stroke Stuffing. Alex.

[TZ350]

Reading Spark Plugs. Steve Tech.

[TZ350]

Reading Spark Plugs to understand general engine condition. Goss Garage.

[dtenney]

DT , the torlon caps I made ( Kentastic actually ) were held in by the clip and covered the pin hole completely.
But yours colour up , and dont fail ?
The tophat welded pins allow lube into the piston pin bearing surface - and show no heat issues at all , plus identical power.
No other difference , so I can only assume for some reason the TM Vertex piston does not have sufficient rear lube entry ( sounds rude , sorry ).
As I said I aborted the Torlon tests as destroying a customer engine isnt really an option - giant blouse I know.

We do see the heat issue referred to by Jan at the outer ends of the wrist pin. Having said that, we have not had any failures. We are running methanol in our motors so I do not know if runnning on gasoline would be ok.

[SwePatrick]

I suppose brake caliper pistons will get hotter than piston pins, so they should be able to take the heat, but taking the heat is no problem for Torlon either;
the problem seems to be with the pins themselves, and using a different synthetic plug material won't change that.

I was thinking it as an cheap easy to come by replacement for those who want´s to test the idea =)

[SwePatrick]

More progress from Alex at Two Stroke Stuffing.

Finally Alex has come to his senses
In my eyes the 100% port with no beam to support the ring is a enginedisaster you install.
Not waiting to happen, you install the problem and it is bound to happen very very soon.

And a hot tips for you Alex, do not turn around the engine directly with that drill after it stopped.
Just turn around by hand first and feel it.
Saves you money in the end, i promise!

[wobbly]

The 100% Exhaust port with the Savice patented reversed Dykes type L ring worked perfectly during hours of testing of pistons and rings made by Vertex.
I dont understand why Alex went off on a tangent with the pinned ring idea , all that was needed was attention to the clearance detail of trapping the ring , preventing any bulge out into the port.
This idea certainly isnt an automatic disaster , its been done , and proven.
Of course a point load on a highly stressed thin section retaining hole is going to cause instant issues.
The original reversed L ring had the bulging load spread out over near 1/2 the vertical legs circumference , and thus was no problem mechanically at all.
And the bore edges of the port need to be chamfered properly , before plating , and dressed afterward with cratex/cotton mops in a die grinder , exactly as is required with a normal 72% port - not just rubbed
by hand with a strip of sand paper.
As always , the devils in the detail.

[SwePatrick]

That L-ring test, Was it a highrevving small engine?
As i always will state that the piston rocks due to it´s tapered form.
And i will still belive that´s why the ring always catches the lower part of the port, as the piston is always prone to rock in tdc and bdc.

Due to rocking, the ring needs to have a bit of travel in and out of it´s groove and never be restricted before the piston rocking is halted by cylinderwall, otherwise it will not seal in upper part of cylinder as it should, and with that loose a lot of power.

A 'lowrevving' non highperformance engine can have less taper to the piston and it makes the piston rock less(less friction,less heat), and thereby have more control of the ring.

[TZ350]

That L-ring test, Was it a highrevving small engine?
As i always will state that the piston rocks due to it´s tapered form.

It is true that a piston is tapered, but the taper is calculated so that the piston become more parallel when it is at working temperature. Because the crown and the upper part of the piston has more mass and runs hotter. For both reasons it therefore expands more. Also the same reason pistons are oval and narrower on the sides to accommodate the expansion of the extra mass around the gudgen pin bosses.

Plenty of performance high revving Kart engines had L-ring or Dykes ring configuration.

[Frits Overmars]

More progress from Alex at Two Stroke Stuffing.

I love watching "Two Stroke Stuffing" on YouTube and seeing how Alex Degnes is enjoying his hobby and at the same time is doing a wonderful job at promoting the two-stroke engine. Of course I also enjoy the way he makes good use of information, like the transfer layout in his present cylinder which mirrors my scavenging concept, his plan to incorporate my 24/7 inlet timing, and now his new cylinder with symmetrical scavenging.The latter will give him a lot more blowdown angle.area than his unbridged exhaust port experiment, and a lot more transfer angle.area to go with the enhanced blowdown.
I can't wait to see his next videos. I don't mind admitting that from time to time it's not only a trip down memory lane for me, but also a shameless ego trip .

[Frits Overmars]

Reading Spark Plugs.

There is just one thing missing in those spark plug reading videos: reading the price tag on a spark plug. I have never in my life chopped a spark plug just to get a better look at its insulator, and to the best of my knowledge neither has Jan Thiel. A 20x-magnifying glass and some light is all you need.

[OopsClunkThud]

The bottom edge of the exhaust could get a huge radius as it has zero impact on the timing. On the sides and roof of the exhaust adding a radius comes at the expense of port area as it has to be done within the confines of the port width and timing. But the port floor is the only part of the exhaust where adding a radius can be outside of the port area at least down to ~BDC.

[jonny quest]

To make the FOS cylinder work, I really think a dished piston, and a downward transfer roof is the answer.

Too much short circuit issues with transfers directly under exhaust port.

[wobbly]

The reverse L ring tests were done on a Rotax 128 , that reved to 14500 , no failures were seen once the radial clearance holding the vertical leg trapped within the piston groove
was correct.
Too tight and it caused premature blowby , too loose and you could see scuffing beginning on the port corner radi.