ESE's works engine tuner

[katinas]

This is what I managed to do.

Very nice job, but would be interesting to rise up exhaust bottom, like Jan done.

[Jannem]

Piston, with low cutouts, at BDC masked big part of cylinder bottom cutout and maybe this again work in good way.
Maybe with low cutout piston runs cooler and more masked trans duct help maintain higher density mix in ducts, before trans windows opens. And at very high revs at BDC, more isolated ducts better resist to exhaust gas. But this is only considerations.
Interesting how many times gas fluctuated in trans ducts at different revs, before transfer windows opens: 1/2, 3/2, 5/2.......

Another consideration is that it effectively makes t-port short and long walls more even in length reducing turbulence in addition to changing tuned length.

[Frits Overmars]

Another consideration is that it effectively makes t-port short and long walls more even in length...

Jannem, abbreviations can easily lead to misunderstandings. When you mention a T-port, most people think of something like the yellow port below.

[Muhr]

Very nice job, but would be interesting to rise up exhaust bottom, like Jan done.

I thought I'd read that it came up but then went down again?

Interesting, if 125 cc rotary engine with 30 mm carb can reach 47hp like TM.

I would say no. but I calculate by hand, maybe the guys with programs say different.

[Jannem]

Jannem, abbreviations can easily lead to misunderstandings. When you mention a T-port, most people think of something like the yellow port below.

Oops. In that context it must sound like gibberish...
I meant transfer port of course, good catch.

[katinas]

Another consideration is that it effectively makes t-port short and long walls more even in length reducing turbulence in addition to changing tuned length.

Yes, a lot of gradually changing areas: intake window, intake to transfer ducts, transfer windows, exhaust windows plus power valve.

[katinas]

Would be also interesting to know where the cutout is located when the transfer begins to open and when it's fully open vs. the cutout in the cylinder.

You need to know the crank web dia., con rod length ( 115 or 120 mm) on this picture, distance from trans windows upper edge to the top of the cylinder and you can easy calculate it. Measure aprox dimension of this piston.

Quick search through pictures and if crank web dia is around 82 mm, then:
With 115 mm con rod, at TDC, from piston cutaway to crankcase - around 74 mm. so at BDC - around 20 mm.
If transfer windows height 14 mm, then 34 mm before trans opens. But this could be not very accurate.

[Muhr]

This is what I managed to do.

better view

[Frits Overmars]

.........

[katinas]

O-
.....but what I tried to do is imitate the rsa as far as I could.

If try continue from where Jan stopped, why not to try exhaust bottom at transfers upper edge level, and then grinding in small steps.
Interesting how bottom exhaust duct shape should look like with this configuration, parallel with upper and oval cross-section or something different,
of course with ......G, H,.......

[Muhr]

If try continue from where Jan stopped, why not to try exhaust bottom at transfers upper edge level, and then grinding in small steps.
Interesting how bottom exhaust duct shape should look like with this configuration, parallel with upper and oval cross-section or something different,
of course with ......G, H,.......

Yes, interesting, is not that a bit of 1/2 what Frits did with FOS cylinder? Or what do you say Frits?
In general, it seems interesting to do more of the processually larger surface area you have in a 50cc. And especially with regard to blowdown.
Tried to find some more info about RSA's blowdown area, without success.

[2T Institute]

Details of the spec Lozza cylinder carb pipe etc.

nf4 cylinder kit hrc spec pipe made from 1.1mm mild steel, zeeltronic ignition total loss. Rest standard nf4.

[Frits Overmars]

Tried to find some more info about RSA's blowdown area, without success.

I wrote about it on http://www.pit-lane.biz/ and I think I also posted a couple of links here to that French thread, some time ago, but I don't remember where exactly, so here are those links once again:
http://www.pit-lane.biz/t117p318-gp1...-part-1-locked
http://www.pit-lane.biz/t117p333-gp1...-part-1-locked

[peewee]

hey guys heres a couple updates as the methanol nitro bike is almost ready to run again or fail miserably . but don't laugh to much since im not a expert welder . this is the changes I made during the winter since the last time riding it about four months ago.

lowered com ratio from 16 to 12.5. I didn't install a com release valve in this head because the last one kept blowing up from the nitro. likely a engineering design mistake on my part. I may try a hand held starter on the crankshaft if I have trouble kick starting it

installed a fourth fuel jet

installed a larger float valve

increased float bowl capacity

grinded the needle richer at idle position

made a new fuel tank of much smaller capacity (2.8L vs 13L with original tank). this now allows easy access to the spark plug and relocated the fuel valve so I could eliminate the fuel pump.

next week im going to a local machinist and making a new reducing exh spigot but unfortunately it wont be water cooled.

I still need to determine if the fuel flow is ok but I think it will be since the bowl capacity is quit alot. with just the fuel valve its 2.8L per 45sec. with the inline fuel filter it slows a bit to 2.8L per 75sec. I haven't yet checked the flow rate of the float valve in the carb or what the approximate engine consumption might be

[wobbly]

This is a favorite hobby horse of Ken Seeber and mine.
Why does everyone leave the transfer duct outer walls uncooled.
I have measured the temp of a race engine at the case deck line on the outside with a press in probe, and its over 80*C when the water temp is at 45*C.
Seems so obvious, especially when it is such a mission to cool the inner duct radius.
Here is crude idea to add enclosing covers down to the the split line.
The other thing that is monkey see monkey do is the insert spigot down into the bore.
This means the squish has no cooling from the side,and is miles away from the water above.
Delete the spigot , and allow water in close to this critical area to help prevent spontaneous detonation of the trapped end gases, simply due to the material behind the
inserts squish band maintaining boundary layer coolness.
This is an extension of having the cold water regime flow over the transfers first,next the Exhaust then up into the head and across and out.
My latest dyno result on here show this is superior to any other scenario.