[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4)

Nombre de messages : 56 Localisation : Austria Date d'inscription : 02/03/2014

Yes basically I am.
Though it would be a more 'high performance' version.

Nombre de messages : 98 Localisation : Italy Date d'inscription : 30/10/2012

hi

has someone ever let recoating a Alu Cylinder by [Vous devez être inscrit et connecté pour voir ce lien]

did they make a good work?

thanks Manuel

I think that the 24/7 could only work if some kind of progressive exhaust frequency control is used in closed loop with engine rpm, otherwise my 1st guess is the load on the engine will disengage the precarious balance

Nombre de messages : 151 Localisation : usa Date d'inscription : 29/09/2013

hi frits i been looking at the rsw drawing and on the front side wall (nearest the main exh) of the A port there doesnt appear to be a kicker like most other cylinders use. is it safe to say the rsa doesnt have a kicker either ?

brokedown a écrit:: hi frits i been looking at the rsw drawing and on the front side wall (nearest the main exh) of the A port there doesnt appear to be a kicker like most other cylinders use. is it safe to say the rsa doesnt have a kicker either ?

I'm old-school, Brokedown; you'll need to define kicker for me.

I have a few questions about the components, can someone give me the impedance values of the HT coil (CO8412020) RSA 125 ?
I am looking for a ht coil with a high transformation ratio aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4) - Page 14 727249

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4) - Page 14 727249

brokedown a écrit:: hi frits i been looking at the rsw drawing and on the front side wall (nearest the main exh) of the A port there doesnt appear to be a kicker like most other cylinders use. is it safe to say the rsa doesnt have a kicker either ?

The RSA cylinder is the standard, that is the cylinder that made the most HP ever for a 2T engine, the one everyone is trying to emulate. The drawings show you how it is achieved, why worry about all those other cylinders?

Manuel Rainer a écrit:: hi

has someone ever let recoating a Alu Cylinder by [Vous devez être inscrit et connecté pour voir ce lien]

did they make a good work?

thanks Manuel

Hi Manuel,
From what i've read and heared they seem to be able to do good plating.
The problem seems to be in finishing the cilinder. Chamfers in the wrong place that kind off stuff.
A dutch Guy has excellent results but he does his own finishing.
He is called JTMX Rion Janssen on fb

The other option is to contact emot (Martijn) he has some good contacts that can do the trick at decent price levels.

Fact remains that finishing is utterly important and should be done right.
Transfers razor sharp. Exhaust likes to eat rings so there you will need a little adjustment from the razor edge.

Its what i know hope it helps a little

S

Nombre de messages : 151 Localisation : usa Date d'inscription : 29/09/2013

Frits Overmars a écrit:

brokedown a écrit:: hi frits i been looking at the rsw drawing and on the front side wall (nearest the main exh) of the A port there doesnt appear to be a kicker like most other cylinders use. is it safe to say the rsa doesnt have a kicker either ?

I'm old-school, Brokedown; you'll need to define kicker for me.

sometimes its called a hook also. im sure youve seen them. alot of times theyre in the front of the A port and rear of the B port. the green circle is what im refering to where it makes a sharp turn like a hook. i was just wondering if the rsa uses any sort of hook in the front of the A port ?

[Vous devez être inscrit et connecté pour voir cette image]

brokedown a écrit:: hi frits i been looking at the rsw drawing and on the front side wall (nearest the main exh) of the A port there doesnt appear to be a kicker like most other cylinders use. is it safe to say the rsa doesnt have a kicker either ?

Frits Overmars a écrit:: I'm old-school, Brokedown; you'll need to define kicker for me.

brokedown a écrit:: sometimes its called a hook also. im sure youve seen them. alot of times theyre in the front of the A port and rear of the B port. the green circle is what im refering to where it makes a sharp turn like a hook. i was just wondering if the rsa uses any sort of hook in the front of the A port ?

Yes, I suspected that this was what you meant. I have seen them a lot on the trailing flank (the sidewall furthest away from the exhaust) of B-ports, but never on the leading flank of A-ports. Those leading A-port flanks should be aimed away from the exhaust port alright, but not with a hook.
Hooks came into being because B-ports needed to be widened but the cylinder studs were in the way. Hooks create pressure loss through turbulence and you don't want a turbulent incoming charge; it would cause undesirable mixing with the spent gases. And of course you don't want the pressure loss either; it spoils the mass flow.

Nombre de messages : 151 Localisation : usa Date d'inscription : 29/09/2013

thnx for the help frits. let me ask something else. on the A port leading flank of the rsw, if you look at its entrance angle into the cylinder and draw a imaginary line to where its destination is, it appears to be somehwere near the bore center.

on the 50cc concept scavenge diagram you posted a while back, it shows the A port leading flanks destination much farther to the rear of the cylinder than the rsw. has there been some new progress since the rsw and thats why the 50cc concept drawing shows the A port leading flanks direction much farther to the cylinder rear ?

brokedown a écrit:: thnx for the help frits. let me ask something else. on the A port leading flank of the rsw, if you look at its entrance angle into the cylinder and draw a imaginary line to where its destination is, it appears to be somehwere near the bore center.

on the 50cc concept scavenge diagram you posted a while back, it shows the A port leading flanks destination much farther to the rear of the cylinder than the rsw. has there been some new progress since the rsw and thats why the 50cc concept drawing shows the A port leading flanks direction much farther to the cylinder rear ?

the A-ports in my scavenging concept point just a tiny bit farther to the rear of the cylinder than the RSW-ports.
Looking at the base of the RSW cylinder gives you the wrong impression: the angle you see there is not as much backward as the radial exit angle of the A-port's leading flank.
By the way: this is the case for most two-stroke cylinders.

Nombre de messages : 98 Localisation : Italy Date d'inscription : 30/10/2012

Sanderhoutman a écrit:

Manuel Rainer a écrit:: hi

has someone ever let recoating a Alu Cylinder by [Vous devez être inscrit et connecté pour voir ce lien]

did they make a good work?

thanks Manuel

Hi Manuel,
From what i've read and heared they seem to be able to do good plating.
The problem seems to be in finishing the cilinder. Chamfers in the wrong place that kind off stuff.
A dutch Guy has excellent results but he does his own finishing.
He is called JTMX Rion Janssen on fb

The other option is to contact emot (Martijn) he has some good contacts that can do the trick at decent price levels.

Fact remains that finishing is utterly important and should be done right.
Transfers razor sharp. Exhaust likes to eat rings so there you will need a little adjustment from the razor edge.

Its what i know hope it helps a little

S

thanks Sanderhoutman

i want to do my one finish anyway. so if i am saying this it can works.

Frits where did you let your cylinders pating?

thanks Manuel

Manuel,

Just make verry clear how you want it done and let them confirm that they agree.

You might want to contact emot first he has iff i recall correctly a spanish company doing it also and that is much closer to home.

Maybe try it with a less important cillinder first.

Nombre de messages : 112 Localisation : Germany Date d'inscription : 07/02/2012

Airsal will also do it...

[Vous devez être inscrit et connecté pour voir ce lien]

They are doing a lot of cylinders anyway (Barikit, Conti,...) and I have good experiences with them. If you have a bridged exhaust port they'll grind it back, just small rework is needed.

Nombre de messages : 14 Localisation : portugal Date d'inscription : 24/09/2013

hi, frits or jan, can you tell if exists any methode to calculate Target rpm from time.area like to calculate the rpm for maximum torque? thanks.
best Regards!

Nombre de messages : 14 Localisation : portugal Date d'inscription : 24/09/2013

another question, which area you use to determinate effective diameter of exhaust port, exhaust port area between blowdown? RSA have 814mm^2 between blowdown aproximated diameter = 32.19mm
and in tubo the efective diameter is 39.2 mm.
thanks

m4grity a écrit:: hi, frits or jan, can you tell if exists any methode to calculate Target rpm from time.area like to calculate the rpm for maximum torque?

I wrote something about that on 24 january 2013; did you find it?

m4grity a écrit:: another question, which area you use to determinate effective diameter of exhaust port, exhaust port area between blowdown? RSA have 814mm^2 between blowdown aproximated diameter = 32.19mm
and in tubo the efective diameter is 39.2 mm.

Comparing the blowdown area to the initial pipe diameter may be somewhat confusing because the exhaust duct is conical; the 39,2 mm is the pipe diameter at a distance of 63 mm from the piston.
The exhaust diameters are based on the blowdown area like you suppose, but calculating the optimum diameters is rather complicated. That is why I posted the simple FOS exhaust concept, so you can get an impression of those values without too much arithmatics.

Now, could you give a short indroduction of yourself? That would be nice.

Nombre de messages : 14 Localisation : portugal Date d'inscription : 24/09/2013

I'm From a little island (Madeira - Portugal) nearest "Canarias" Islands (Spain),
I'm just a curious of 2 strokes engines :)
I'm a student of mechanical engineering in Portugal Main Land, and a like a lot to learn! Very Happy

hum, I understand, but you have any coefficient to apply for the angle of exhaust duct?

Thank you :)
Best Regards Frits!

Ps. Sorry about the english!

Nombre de messages : 14 Localisation : portugal Date d'inscription : 24/09/2013

Frits Overmars a écrit:

m4grity a écrit:: hi, frits or jan, can you tell if exists any methode to calculate Target rpm from time.area like to calculate the rpm for maximum torque?

I wrote something about that on 24 january 2013; did you find it?

Yes I read this, but this formula is for the torque maximum, and I'm asking if exists also to the peak of the engine power. (Maximum HP) or it just trying?

Nombre de messages : 44 Localisation : Portugal Date d'inscription : 08/11/2011

You can work backward from the BMEP formula to get rpm from torque and horse power, keep the number sensible and it will give you a sensible output, garbage in = garbage out.

Nombre de messages : 14 Localisation : portugal Date d'inscription : 24/09/2013

senso a écrit:: You can work backward from the BMEP formula to get rpm from torque and horse power, keep the number sensible and it will give you a sensible output, garbage in = garbage out.

I just thin, that could be exist an formula like the duple integral to calculate the rpm like torque, using Time.area.
I will try it, thanks :)

Nombre de messages : 44 Localisation : Portugal Date d'inscription : 08/11/2011

Remember that any value calculated from time area will be totally theoric,with no real world mean, because its just something form an area times degrees, there is no flow influence on that, angles, effect of exhaust, ignition timing, carburation, pipe resonance, and a lot more details..

I assume you are curious about the numbers that I posted on facebook and how did I arrived at them.

Nombre de messages : 14 Localisation : portugal Date d'inscription : 24/09/2013

senso a écrit:: Remember that any value calculated from time area will be totally theoric,with no real world mean, because its just something form an area times degrees, there is no flow influence on that, angles, effect of exhaust, ignition timing, carburation, pipe resonance, and a lot more details..

I assume you are curious about the numbers that I posted on facebook and how did I arrived at them.

It's totally theory, but, if you don't understand the theory, you will never understand the real world, I think..

in propose, who are you? aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4) - Page 14 771973

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4) - Page 14 771973

I had an idea. What if there was a tube connected to the pipe and on this pipe was a reedvalve that allowed fresh mixture into the pipe. It would be connected to a tube to the carburettor before the reedvalve or rotary valve. It would bypass the transfer port/ crankcase route to allow fresh charge to be directly put into the pipe during the scavenge cycle. Then it would be available to put back into the cylinder.

» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 3) (Locked)
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