The 50

[cotswold]

Yuck. Gears are the future. I can see the advantages. I have raced an auto scooter, its a different ball game as far as riding goes. My advice is look into rear bake systems that will give max control. Its all about the rear brake to tip in and keep mid corner stability. But after that its all a bit boring. Fast boring though.

It's just another project I fancy trying, not a replacement for the Honda

[F5 Dave]

So it it an AM6 engine Tim?

I have just started getting my 50 into engmod. A few lessons already. My reeds don't have enough area to make the power I want. Also pipe needs a small adjustment. But that timing of 192 / 130 is hard to beat.

31* blowdown is not much at all. You'd have to have mondo ex area above the transfers to make that work. I've been running 196\128 on the single Port, but even on the triple with same timing the symptoms are blowdown limited. (Though the auxs are way small, I did them 10 yes ago before I'd seen an RSA barrel).

Heck in the old days I ran 202 at 12000. But clueless then. As now.

[richban]

31* blowdown is not much at all. You'd have to have mondo ex area above the transfers to make that work. I've been running 196\128 on the single Port, but even on the triple with same timing the symptoms are blowdown limited. (Though the auxs are way small, I did them 10 yes ago before I'd seen an RSA barrel).

Heck in the old days I ran 202 at 12000. But clueless then. As now.

Engmod is saying 192 to 194 all Good. 196 loose power. 198 loose more power. Not messed with the transfer timing yet. This is all based on the pipe it is currently running. The Malossi pipe Frits so kindly supplied.

[F5 Dave]

At what peak revs? You're T port with barrel?

Most gp bikes were around 33 deg. But single port is what we had to play with until recently so needed much much more.

[richban]

At what peak revs? You're T port with barrel?

T port, 14K

[F5 Dave]

Gosh. Maybe Frits and engmod know more than me. Do ya think?

[richban]

Gosh. Maybe Frits and engmod know more than me. Do ya think?

Ha. Well I am going to re measure everything again soon. But looks like close to 20hp is not that far away.

[husaberg]

Google told me
http://www.mopedarmy.com/wiki/Moped_..._stud_spacings

he told me this too
http://www.apriliaforum.com/forums/a.../t-242814.html



http://www.mopedarmy.com/wiki/Moped_..._stud_spacings

Cheers Husa but this only tells me what wont fit , I already found that one. I was hoping that the Aprilia RS had the same spacings and one of our Euro friends confirmed it for me

Er....that second link half way down the page.

[cotswold]

My SR50 now has an RS50 cylinder, not too difficult to make fit, just a couple or three hours with a dremel, have been gifted an RG50 frame which I'll put my NF4 front into but the rear wheel is going to take some work

[sonic_v]

My SR50 now has an RS50 cylinder, not too difficult to make fit, just a couple or three hours with a dremel, have been gifted an RG50 frame which I'll put my NF4 front into but the rear wheel is going to take some work

What stroke are you running?

[cotswold]

What stroke are you running?

I'll stroke it to the stock Aprilia RS50 Bore x Stroke, 39,86 x 40 mm.
it has an after market crank in it but would want the big end upgraded so would stroke it at the same time to make things easier in the long term.

[dark art]

I'll stroke it to the stock Aprilia RS50 Bore x Stroke, 39,86 x 40 mm.
it has an after market crank in it but would want the big end upgraded so would stroke it at the same time to make things easier in the long term.

There are some AM6 engines that have the 40.3 bore x 39 stroke. Always thought the 40x40 is the piaggio engine on newer aprilias.

[Juho_]

I have just started getting my 50 into engmod. A few lessons already. My reeds don't have enough area to make the power I want. Also pipe needs a small adjustment. But that timing of 192 / 130 is hard to beat.

What reedvalve are you using?

Could you tell us, how much your cylinder has blowdown area?
Just curious, because I'd guess the cylinder must have a lot of blowdown area (very wide exhaust port) to be able to reach approx. 20bhp @ 14krpm.
Based on my tests.

And how much power does the engine lose with e.g 198 degrees duration exhaust port, compared to 192 degrees?
If I understood correctly, you meant peak power?

[richban]

What reedvalve are you using?

Could you tell us, how much your cylinder has blowdown area?
Just curious, because I'd guess the cylinder must have a lot of blowdown area (very wide exhaust port) to be able to reach approx. 20bhp @ 14krpm.
Based on my tests.

And how much power does the engine lose with e.g 198 degrees duration exhaust port, compared to 192 degrees?
If I understood correctly, you meant peak power?

Hi There.

Reeds are a Stage 6 setup. Not the vforce version.

I need to go over all the port measurements again to get everything more accurate. The first measure up was not that accurate. More time is needed. I have put the engine back together to go racing. The only change I made was adding lots of exhaust port side angle area. I will also order the Vforce reeds and then dyno it. I will let you know how I go. Re 198 V 192 timing. From memory ether way you went it lost 2 hp on top and 1 hp everywhere.


Thanks Rich.

[Juho_]

Yes, the 'regular' Stage 6 reedvalve is about the same size as stock Minarelli AM6 if I remember correctly.
VForce reedvalve (Stage 6 or Top Performances.. they are very similar, expect the stuffer is different shaped) will make a great difference.

I did some small and quick tests.. and with the VForce (Top Performances) reedvalve power improved everywhere.
Peak power improved +7,6%, running very lean WOT (with stock reedvalve it had been jetted for the best peak power, when hot engine).. ran out of main jets, so ended the testing 'till I get larger jets.


But very interesting results. Thanks for sharing them!
Especially the exhaust port timing. Got me more inspired on trying different exhaust port timings (transfer timing @ 130 degrees) on my engines.