Aprilia SR 50 R

[JacobLeSann]

On word of the power valve, I’m not sure. Maybe? As of current, I have a beginner’s understanding of this scooter’s mechanicals. Maybe a year from now I’ll have better knowledge to answer that. I’m new to motorized bikes of any sort.

A super helmet! That’s the future right there, like the Rocketeer or something! Haha, in seriousness though I have considered helmet mods. I designed an aero spoiler for a bicycle helmet and a similar spoiler for my backpack; pretty funny ideas.

Yes, the spoiler is not too effective, but I’d think it has some use. After seeing it being called useless I’m considering adding something to stabilize airflow behind my head. At the same time I kinda like the “shelf” and think it looks ugly with a turtle-deck there.




Bleh. Even uglier than current.

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Here’s some photos of the bike right now. I redesigned the rear into more of a tail.




On the left, there is a flared portion that fits over the swing arm. I’ve made a little intake duct to allow air to flow into my aftermarket air filter. This seems to work well and I’ve noticed it is clean in there. I put a little too much taper at the rear but I made sure to have a sharp edge all around for good flow separation.



On the right, I’ve flared out the panel to allow the exhaust to fit inside. There’s an upper intake (crude) behind the foot board and a lower intake (better) below. I designed these to allow airflow into the fairing to cool the exhaust as well as blow out the fumes coming out of the bottom. There’s a little white patch behind the duct, and that’s a fix for the original design, where I ended up blocking the exhaust’s down-spout. I noticed a cigarette smell while idling at a stop light. I added a patch with a slight flare and then cut out the bottom area of the fairing to fix that.



I tried to add what I could to the bottom and inside of this fairing, in an attempt to try and get some flow attachment there.



At the rear, I added a separation edge around the exhaust “box”. Whether this helps (by giving a bit more guidance between the air coming off the sides and the air dumping out the vents), or just looks cool, I’m not certain. I think it looks both like a toaster as well something out of Star Wars.




I actually just got home from my evening commute, this time on the bike. I rode the same route yesterday, and then went cruising around town and some country roads. Screwing around between 0-50 km/h to 75-90 km/h, I travelled 60 km and knocked one bar out of the gas gauge. If that’s to believed, I spent a good 1.12 litres. I think that’s great!


I plan to keep riding the bike while I remove the fairing sections and paint them. I think this can help give me better insight into the difference made.

[cRiPpLe_rOoStEr]

Originally Posted by JacobLeSann

On word of the power valve, I’m not sure. Maybe?

I don't remember having ever seen such a small engine fitted with one, actually. Some time ago I actually spotted a scooter similar to yours, but I'm not even sure if the one I saw also had the direct injection

[JacobLeSann]

Finished up the first proper tank fill. I am still proclaiming my figures as estimates (as this thing is hard to get mileage measurements from), but it looks like I went 248.9 km (154.65 miles) and burnt away 5.83-6 litres (1.54-1.58 gallons). Total looks to be 97.87 or 100 MPG. Reason for the difference in range is that I don’t know exactly how much is left in the tank.

That’s great! I spent the first part of the tank ripping around the streets testing out the bike, the second part of the tank rushing at 85 km/h (9500 RPM) to work, and the last third cruising the highways late at night. I wasn’t fully trying to hypermile the tank and didn’t have my bodywork for the last half.

As for the lack of aero-mods, I noticed the bike is louder without. There’s a good bit of whistling going on. It seems I couldn’t quite get over 86 km/h and the engine was really screaming.

The handling is just fine. The appeal of this seating position versus lower feet-forward bikes is that I can lean forward and stand up. Ive managed to hop over some potholes and ruts in the road, fully lifting the bike off the ground a bit. Shifting forward allows nimble handling; I’d say as nimble as the original seating position. I’ve noticed that sitting so low in a flat seat means I need to lean more to make the sharper turns. More input needed to make the same adjustment; it’s like balancing a broom handle versus balancing a hammer. This could be a problem if I was on a race track as the tread wants to run out in sharp high-speed turns, but it’s a 50cc scooter so no biggie.


Anyhow, those are my observations. I’ve revised some of the bodywork and I’ll update results on that soon.

[JacobLeSann]

Just realized I haven’t reported back for a while, whoops!









I’ve been riding it lots. Finished up the paint in a night and then threw on a bunch of stickers and profane graffiti. A guy at the gas pump told me I had a nice ride and I just laughed and thanked him; hope he wasn’t being serious.


I’m used to riding worse vehicles, so I find the riding position to be just fine. I have ridden over 150km straight on this bike more than once, with no issues. In fact, I got hopped up on an energy drink and went off the road. Rode through rough 8” deep ruts, mud, snow, and water. Dropped the bike once or twice, but it’s very easy to recover thanks to the low seating position. It never did hit the ground. Sketchy, though.


The strength of the fairing is impressive. It plowed through ruts in the mud at 50 km/h and only managed to pop out a screw or two. I can punch it, throw it, kick it…everything. On top of the strength, it is light! It floats to the ground if you drop it from above the shoulder. Very cool stuff.

As for mileage, I haven’t really been calculating professionally. I’m a very busy guy and simultaneously a terrible procrastinator. A lot of the time I end up riding 80-85 km/h to work, sometimes more. Nonetheless, I am getting 250-300km per tank. I have not yet gone to the pump with a tank below 200km. When the bike was stock, I could get around 190km at similar speeds. I see that as a victory!

Best of all, nothing is finicky. Exhaust temp is good. Engine temp is good. Nothing is catching fire or melting. No turbulent whistling or flexing under pressure. Very stable. There does seem to be a slight wobble in the drivetrain. That’s about it.


So, I’d call that a win! Feels great to fill up for $8 and drive a whole week! The prototype has met all my desires. Will update if I make anymore discoveries. Thanks to all for input and interest.

[freebeard]

Looks comfy.

[cRiPpLe_rOoStEr]

Sure it's an interesting setup, yet comfortable might be an understatement. Well, with my awful knees I wouldn't try it. BTW what have you used for the seat, and what seems to be a headrest integrated to the topcase?

[cRiPpLe_rOoStEr]

Quite similar to yours, but this one is most likely carburettor-fed. IIRC it has a reed-valve setup, which might not be actually needed for the ones fitted with the direct injection like yours.