Aprilia SR 50 R

[JacobLeSann]

Hey all,

I have been thinking about modifying my 2007 Aprilia SR 50 R. It’s a 2-stroke 50cc with an EFi system that gets 90-120 MPG as I commute with 50-80 km/h speeds. It’s already very clapped out so I don’t feel bad about chopping it.

My original big plan was to chop it into a recumbent bike, inspired by Akira. I’ve been so busy with cars that I don’t want to do that right now. I figure a better idea is to use coroplast and aero mod the existing frame. I have lots of coroplast already so it should just cost me for pop rivets and paint. Doesn’t have to look good as it already brings laughter lmao.


So what do you think?

[cRiPpLe_rOoStEr]

Is that engine fitted with the direct-injection system originally developed by Orbital?

[JacobLeSann]

I’m not sure. Mine has the Morini engine with Ditech injection. I believe it works off some sort of crazy air compressor setup.

[JacobLeSann]

I stripped the fairing pieces of the bike to get a good look at the frame. I figured I have enough time to do some modest changes on the bike.

Right away, I noticed that the helmet storage area (under the seat) could be used as a spot to sit.



I think this will work perfect for the first stage of modifying this bike. It seems like it won’t take much effort to make a seat and move the feet down a bit. It’s not much for drag reduction but it will absolutely cut the frontal area down. I’m curious to see if handling will improve.

[cRiPpLe_rOoStEr]

Originally Posted by JacobLeSann

I believe it works off some sort of crazy air compressor setup.

That air-assisted injection was developed by Orbital, as a guide to the fuel spraying pattern.

[JacobLeSann]

So far so good!

Haven’t had to make all that many changes to get the seat in. Just careful marking and cutting with handheld jigsaw. I realized fast that I couldn’t fit into the helmet bucket so I cut most of it out and made a custom seat. I used a piece of flat 1/4” plexiglas and cut a blank out. Tried to use a heat gun to bend it but it just snapped. I put it in the oven at 300 degrees until it became malleable and then I notched it on top of the desk chair in my shop and sat down. Very hot but it’s nicely molded to my rear.

Mechanically, all I needed to do was reroute the fuel filter. You can see in my photos that I’ve carved out the right side of the seat bucket, and stitched in some plastic. That’s to make room for the new routing. I’ve also removed the stock air box and will be replacing it with a washable cone filter and an air box of my design. The stock one is good from a dust perspective but very restrictive and way too bespoke to find replacement filter otherwise.


Anyhow, I feel like Kaneda. More scrunched up, though. Almost like riding a BMX. I don’t mind; it’s much better than how I rode it before.



Here’s what’s on my mind for tomorrow. I plan to mount the storage pod right behind my back and use some plastic to streamline it into a nice kammback tail. I also want to use some scrap plastic to clean up little open areas and try and smooth flow. Wheel discs too, if I can. Most importantly, a dustbin fairing for the front. The radiator is mounted above the front wheel, so a dustbin will work perfect. It even has exit ducts on the stock fairing behind the front wheel opening!


Excited to see what kind of numbers I get. Wonder how fast it’ll go.

[Cd]

Look up Craig Vetter. He has been aermodding scooters for years. It sounds like what he has been doing is exactly what you are trying to do.



So, have you considered laying back, instead of crouching forward ?

[Cd]

Something that Craig learned, was that crosswinds are brutal when you have a long tail like that.
Window screen allows some of the crosswind air to pass through, while directing the rest of the air in the path you want.

Edit : I was only slightly familiar with the bike.
After looking at it again, I have to say, I would love to see you come close to the look.
The main thing I worry about is safety. You would be so low to the ground that people would not see you - and those that do wouldn't be able to judge at what distance you were because it's so foreign to people. https://commons.m.wikimedia.org/wiki...Akira_moto.jpg

I see you just posted the lay back design. Love it.
Most definitely has the Akira vibes.
I wonder if there is a way to lay back the entire front end without too much work . ( future designs )
I like the angular look too of your sketch.
BTW, You have skills with your art !

[Grant-53]

Some states have a minimum seat height laws. A 15% reduction of body shell to a Kamm effect tail would help with the crosswinds. Make sure the center of mass is ahead of the center of pressure.

[cRiPpLe_rOoStEr]

Originally Posted by Cd

This position doesn't seem so comfortable.