[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked)

I have allways found between 38 and 52deg gave the best power on my dyno testing 125 to 250cc engines

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 17 771973

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 17 771973

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 17 980796

Howard Gifford a écrit:: I suspect the designer of Tubo-120 wanted a longer , more agressive reflected wave therefore he designed the baffle cone larger and the result was a slightly tapered mid section.

Good guess, I think 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 17 771973

Hi everyone 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 17 980796

On this RSA piston picture red arrows shows the material which is hardening piston around pin, does it affect mixture flow under the piston into the transfers when it goes down to BDC.
The same question is for blue colored piston edge, would it be better for the flow to transfers if that edge is lower to the same layer as the piston pin material, and is it better for mixture suction into crankcase that all transfer ports and boost port are opened when piston goes up to TDC.

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Second picture shows different piston design in that area which could be also weaker.

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The second picture shows a forged piston.
We had forged and cast pistons.
Cast pistons gave slightly more power.
So the interior design of he piston seems to have little influence on HP.

While we're on the subject of coolant systems could those of you that know a thing or two about coolant system design please critique mine? Anything I should do differently? I've tried to follow the RSA as closely as possible. Cylinder is 79.7mm bore to put things in perspective. Thanks for any help.

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Most cylinders have a small "box" of water just on the top of exhaust duct. Yours don't

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romeuh80 a écrit:: Most cylinders have a small "box" of water just on the top of exhaust duct. Yours don't

So I need to cool around the exhaust under the power valve too. Correct?

PVO a écrit:

romeuh80 a écrit:: Most cylinders have a small "box" of water just on the top of exhaust duct. Yours don't

So I need to cool around the exhaust under the power valve too. Correct?

It was said in the previous page that good cooling of the exhaust duck did not kill HP.

Soo, I think you are asking for the same answer a second time Wink

By the way, I would love to work on your work 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 17 771973

PVO a écrit:: While we're on the subject of coolant systems could those of you that know a thing or two about coolant system design please critique mine? Anything I should do differently? I've tried to follow the RSA as closely as possible. Cylinder is 79.7mm bore to put things in perspective. Thanks for any help.

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congratulations for the work!
The water box around the exhaust port is very little tikness... the sand mold may break...

romeuh80 a écrit:

PVO a écrit:

romeuh80 a écrit:: Most cylinders have a small "box" of water just on the top of exhaust duct. Yours don't

So I need to cool around the exhaust under the power valve too. Correct?

It was said in the previous page that good cooling of the exhaust duck did not kill HP.

Soo, I think you are asking for the same answer a second time Wink

By the way, I would love to work on your work 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 17 771973

Yes, I probably was. May have been trying to avoid doing more work too. Wink

Anyway is this better or I have I created a dead spot where it won't flow much over the top of the exhaust?

Thank you for your compliments.

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SB07 a écrit:

PVO a écrit:: While we're on the subject of coolant systems could those of you that know a thing or two about coolant system design please critique mine? Anything I should do differently? I've tried to follow the RSA as closely as possible. Cylinder is 79.7mm bore to put things in perspective. Thanks for any help.

congratulations for the work!
The water box around the exhaust port is very little tikness... the sand mold may break...

Thanks, and thanks for the tip. I will try to make my water box sufficiently thick.

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

hallo at all.

my name is Manuel Rainer and i am from italy. My whole life is 2 stokers and specially rotary valve engines. i drive kart 125 and scooter with a rotary valve.

at this point i want tanks at all those who share their knowledge with us and specially Jan and Frits.
you are helping me to make my engines faster.

now i had some questions for Jan or Frits:

can you post an image how was cutet the last version off the rotary valve in the RSA engine? and what were the opening end closing angles (starte openig, full opent, starte closing, full closed).

what was the balance factor of the RSA crankshaft and did you tried some different factors?

many thanks Manuel
[left]

Hi Everyone!

I have made some interesting observations on PVO's pictures, what I'd like to share with you. From above you can see clearly the auxiliary exhaust passage's angle and direction. PVO says that he wanted to have the best copy of the RSA and no doubt the shape of the passage is almost the same as the shape of the passage on the pictures published by Mr. Overmars and Mr. Thiel.

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As you can see I have marked with red on the two pics. But Mr. Overmars has also uploaded another RSA cylinder on which the auxiliary exhaust passage seems to be completly different as on the two pics above. What's more somebody else has uploaded a 3rd pic as well which looks like the same as Mr. Overmars's pic.
It is obvious that on these last two pictures the exhaust passages don't looks toward the center of the cylinder.

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These differences are not negligible so could you please give me some explanations?

Thanks a lot!
Forgi

Feedback on revised coolant design is appreciated! Thanks everyone for your help.

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

hello

PVO wich drawing program do you use?

thanks Manuel

Manuel Rainer a écrit:: hello

PVO wich drawing program do you use?

thanks Manuel

Hi Manuel,

Solidworks, but I'm not sure if I would recommend it. There may be better ones out there. If I had more time I would learn Catia V5 or V6.

Paul

@ PVO :
as you make your own cylinders, why don't you cool the A and B ports ? (inside part of the duct)
by this way you would cool down the mixture

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

Hi Manuel,

Solidworks, but I'm not sure if I would recommend it. There may be better ones out there. If I had more time I would learn Catia V5 or V6.

Paul[/quote]

hi Paul

i only had Inventor 2011, but for me it isn't very good to draw thing like a cylinder

manuel

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

to design a cylinder with complex geometry catia is probably the best program. V6 is hard to install on a single PC as it is using a highly integrated PDM system.

inventor is mainly for plant engineering, solidworks should do the job though.

Stephane a écrit:: @ PVO :
as you make your own cylinders, why don't you cool the A and B ports ? (inside part of the duct)
by this way you would cool down the mixture

The water comes from the exhaust side, soo that would probably heat more than cooled!?

romeuh80 a écrit:

Stephane a écrit:: @ PVO :
as you make your own cylinders, why don't you cool the A and B ports ? (inside part of the duct)
by this way you would cool down the mixture

The water comes from the exhaust side, soo that would probably heat more than cooled!?

That may be true if you draw the water from the exhaust area. To get around this I think you would have to run two more ducts up from the cylinder base separate from the exhaust ducts. This way cool water would be going up between the transfers. It would complicate the design of the crankcases a little bit more.

At this point I'm undecided if I want to pursue this.

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

The RSA crankcase seems to be water cooled, so maybe there is some advantages to cool the lower end of the cylinder, or at least have a more uniform temperature distribuition in the engine perhaps..

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the heat of the gear box don't come to the cranckcase

romeuh80 a écrit:

Stephane a écrit:: @ PVO :
as you make your own cylinders, why don't you cool the A and B ports ? (inside part of the duct)
by this way you would cool down the mixture

The water comes from the exhaust side, soo that would probably heat more than cooled!?

not if there is enough water flow

Nombre de messages : 62 Localisation : Denmark Date d'inscription : 12/02/2012

Forgi a écrit:: Hi Everyone!

I have made some interesting observations on PVO's pictures, what I'd like to share with you. From above you can see clearly the auxiliary exhaust passage's angle and direction. PVO says that he wanted to have the best copy of the RSA and no doubt the shape of the passage is almost the same as the shape of the passage on the pictures published by Mr. Overmars and Mr. Thiel.

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

As you can see I have marked with red on the two pics. But Mr. Overmars has also uploaded another RSA cylinder on which the auxiliary exhaust passage seems to be completly different as on the two pics above. What's more somebody else has uploaded a 3rd pic as well which looks like the same as Mr. Overmars's pic.
It is obvious that on these last two pictures the exhaust passages don't looks toward the center of the cylinder.

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

These differences are not negligible so could you please give me some explanations?

Thanks a lot!
Forgi

This is because the 2D drawing is from the old Aprilia APC cylinder, while the cylinder on the RSA is a APF cylinder. APE and APF have same ports/ducts but different cooling. You should try to get as close as possible to the RSA design.

lay out F-F (sezione F-F) aprilia drawing, is not true... is a projection, but indeed bosster porting are different...

» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)
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» [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 4)
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