ESE's works engine tuner

[TZ350]

page 1770 ........

[Jannem]

Thanks for this explanation. So do you think this is a direct result of the fuel not being atomised enough by the time it has gone through the transfer ports? If there was more turbulence, or more happening to smash up the air fuel mix, do you think this will still be happening?
Thanks again,
Neil

I think several things have an impact. As you'd expect, better atomisation leaves less residue. Carburetion, higher pressure differential across T-port can help or hinder atomisation. Transfer port shape has an impact how well the fuel stays in suspension, direction where it's likely to wet, if that's going to happen.
As Wobbly stated (if I understood correctly), the good squish action cleans up the perimeters from wet fuel and keeps it cooler preventing (or reducing) burn there. Fuel on piston top will burn, but less cleanly than atomised mixture and leaves soot.
Carbon formation on top of the piston, under the chamber, may also improve combustion as it forms an insulating layer retaining more heat in the combustion.

you can substitute " cooler area " with "fuel washed " as the combustion process only burns on a black surface on the piston where it gets hot enough to do so.
I have seen countless engines where the piston is clean alloy directly in line with a port divider - ie no cooling flow to prevent oil deposits burning on a coating.

There is a contradiction in how you state this if you'd expect burning fuel on the surface to leave a carbon residue. -> Fuel burns where its hot enough. -> Clean in line with divider where there is no cooling flow to prevent burning.

So I take it your thinking is that burn on wetted surface does not leave a residue?

[Greg85]

Here is the inlet of a KZ10C ,this starts to resonate with the reed petal frequency and the case volume at around 12500, with peak Hp at 13500.
In EngMod you can see this happen as the case depression drops below atmospheric at the same time as the positive return wave in the inlet goes positive.
This creates a huge + and - pressure ratio effect on the reeds between BDC and TPO and opens them very quickly and early.
The same situation exists in the Aprilia RSA in that it is mechanically very hard to get the inlet short enough to work correctly at those rpm.

Hello wobbly here is the admission reed box modena mkz new homologation 2016 engine tested on the dyno not very good 43.44hp original carton by testing a standard reed box we made a good a 44.93hp what do you think a problem of resonance or the Direction of flow? thanks

[Greg85]

331736[/ATTACH]

this is result of dyno test

[Frits Overmars]

A 7 thou plastic shim at 45 deg is very close to 0.25mm and works very well on model engines. ..Other times I use a 4 thou shim and sit it on the piston crown and poke it to the side of the ports.

If you use shims as thin as that, there is a risk that they will get pinched between the cylinder bore and the top land of the piston if you force the piston upward with some effort. That is why I chose a 1 mm shim Neil. It also gives me better control over that 45° angle.

[Lightbulb]

I figured that would be the case for full sized engines. But with 2.5cc engines and only a 14mm stroke, 1 mm shim is a lot.
You going to the F3D world champs?
Neil

[Frits Overmars]

I figured that would be the case for full sized engines. But with 2.5cc engines and only a 14mm stroke, 1 mm shim is a lot. You going to the F3D world champs?

Yes, 1 mm is a lot in an engine that small, but that won't matter. Of course with so small a bore I would use a 1 mm bicycle wheel spoke instead of a shim, so that the exhaust port's top curvature (if any) won't influence the height reading. Well alright, it might also be a 0,5 mm spoke .
I'm afraid I won't be able to make it to the F3D races in Sweden Neil. But if you are coming over anyway, Germany is just around the corner...

[Frits Overmars]

hey guys im making the swingarm longer by 5". im not much experience in structure design but heres my idea...

Peewee, in addition to every advice that has already been given, and to which I fully subscribe, I'd like add two points.
1: Make the cut as close to the rear axle as can be combined with inserting internal strengthening profiles of the correct length.
2: Can't you add some form of triangulation? That would kill two birds with one stone: much less stress on the welds and a much stiffer fork.

[Frits Overmars]

I think I could learn something from hearing about the design intent of this FOS Malossi pipe and/or the matching cylinder. I'm unsure why there is no stagger on the transfers, noted on the design as all being 130 degrees. Wouldn't it be better to maximise the exhaust aux port size for more blow down and open the A ports later to prevent the short circuiting?

Chris, the reason could not be any simpler: the A-ports were already that high when the cylinder left the factory.

The pipe seems to have a long tuned length at 714mm and the ignition was noted at 16 degrees at 13,000rpm. Maybe I'm being presumptuous but the engine seems to be designed to make peak power somewhere around the 13,000rpm mark. Isn't that a bit low for a 50?

Design rpm was 13300 and that would indeed be pathetically low for a 50 cc racer. But my intention was not to build a 50 cc world beater; I merely wanted to modify a mass-produced engine so it could be used in moped races by guys and girls who had to finance their hobby with newspaper delivery. That Malossi cylinder fitted various moped and scooter engines and it did not require much work to turn it into a winner back then.
The mods, in case you are interested, were:
Raising all transfers to 130° and widening the B-ports to 14 mm.
Raising the main exhaust to 194°.
Raising the auxiliary exhausts to 188° and squaring the windows.

Was this Malossi engine runing on unleaded fuel?

Yep.

[Greg85]

this is result of dyno test

Here is the result for the modena the other result was a tmkz10b

[SwePatrick]

Enjoy! (videoclip)
(trying to sort out fuelstarvation)





One of the pulls is 72.9hp calculated crank hp at 13150rpm.

I got this problem with starvation with softer reedpetals, i got a mikuni 70l/h pump driven by crankhousepressure.
I figure the pulses are weaker at high rpm, reed is almost constant open.

Rgds.

[wobbly]

The reed block in the Modena seems like a good idea to split the flow and direct it toward the transfer entry area.
But the problem as I see it is that bending the flow sideways like that will immediately cause a flow reduction in total.
And this ignores the fact that a large amount of the flow in a normal " square " reed block, flows over the outer sides, not just thru the curtain area at the tip.
I have a picture of a reed with the opposite idea, this gives the side spill over flow room down the sides to flow along the reed box side walls toward the transfer entries.
Two other things, it appears to make good mid power, but falls over in the top end.
Does that reed have a soft petal on top and a stiff petal on the bottom - TM use the same petals now ( soft ) but use two stiffeners on the bottom.
The other thing to look at would be a spacer between the stiffeners and the main petals, some reed makers use this idea along with cutting away the to reed
near the clamp to soften it.

PS - now do you know why not one fast Modena is being used in the 1st 3 rounds of the Euro Champs - all TM KZ10C , maybe two Vortex.

[guyhockley]

I think several things have an impact. As you'd expect, better atomisation leaves less residue. Carburetion, higher pressure differential across T-port can help or hinder atomisation. Transfer port shape has an impact how well the fuel stays in suspension, direction where it's likely to wet, if that's going to happen.
As Wobbly stated (if I understood correctly), the good squish action cleans up the perimeters from wet fuel and keeps it cooler preventing (or reducing) burn there. Fuel on piston top will burn, but less cleanly than atomised mixture and leaves soot.
Carbon formation on top of the piston, under the chamber, may also improve combustion as it forms an insulating layer retaining more heat in the combustion.



There is a contradiction in how you state this if you'd expect burning fuel on the surface to leave a carbon residue. -> Fuel burns where its hot enough. -> Clean in line with divider where there is no cooling flow to prevent burning.

So I take it your thinking is that burn on wetted surface does not leave a residue?

Couple of examples:

[guyhockley]

Wonder if this stuff would be of any use for our purposes?
http://www.greenstuffworld.com/en/re...ld-4-bars.html

[SwePatrick]

The reed block in the Modena .....

Answering me?

Yes, i got soft petals at top and stiffer at bottom.
Actually i dont have any stiffeners at all.
I can´t really say it falls over, at 13300rpm i got 27ms pistonspeed.
It still produces 68hp to the crank at ~13600rpm, after that i aren´t man enough the keep the throttle open
I also got 40.6Nm at ~12600rpm

A screenshot of top of the register, i havent got rest of register in front of me now, but it starts pulle quite hard already at 8500-9000 rpm, i remember averagehp though, between 9500 to 13100rpm, this is almost 59hp