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Nuts & Volts
24 January 2011, 1420
Anyone ever had experience riding either of these an derbi gpr50 or aprilia rs50. I am out in Cali right for the next couple of months and all I have is my electric bicycle to cruise around on. So I saw some of these bikes on craigslist and was think they could let me explore a little farther and faster than my ebike. I've seen a derbi gpr 50cc stock at $1200 and a derbi gpr with a 75cc upgrade for $2000.

My thoughts were that I buy one of these and ride around on it while Im here and then use the little bike for my next conversion?

So any experience or know-how on these bikes? I know they only top out around 60-70, but they are crazy light and will be a good bike to learn on (ive only ridden my electric). Other concerns will they handle an added 50 lbs or some when converted and do you think they can handle the added power and higher speeds? Lets say about 250 Nm from a motor and 100mph top speed?

Thanks for any info
Kyle

Richard230
24 January 2011, 1505
You have come to the right place, Kyle. You may recall that I owned a 2003 RS50 until it blew up over a year ago. I then gave it to my son-in-law, who sold off the IC parts and kept the rest of the bike to use as a hub-motor electric build. He hasn't started the project yet and the poor running chassis just sits in his garage.

I had one of the last street-legal Aprlia RS50's imported into the US. When it was stock, it was a real dog. Top speed is an actual 55 mph (60 on the speedometer) and it was almost impossible to get moving from a stop when facing up hill. There was no power below 8000 rpm and it ran out of steam at 11,000 rpm. However, it ran fine on level ground - once you got the rpm up to 8000. The handling was just OK, due to its crummy rear shock and comfort was minimal. The seat was hard and the handlebars made you feel like you were doing push ups all the time. Fuel mileage was around 60 mpg. I had fun riding it, but it was the most work to ride of any motorcycle that I have ever owned.

I hopped the engine up to race specs, with an 80cc big bore kit, 24 mm carb (stock is 12mm), carbon fiber reeds (twice the area as stock), Arrow expansion chamber, K&N pod filter and on and on. Power doubled from 6 hp to 13 hp, and top speed increased to 70 mph. With a lot of revs and clutch slipping it would actually move uphill from a stop. The only problem was that the motor would blow up every 1000 miles, piston circlips would come loose, the rings would break and finally the piston stuck in the bore, breaking the connecting rod. So it is a great bike for electric conversion. Not much room in the chassis for batteries, though.

Let me know if you have any other questions.

Nuts & Volts
24 January 2011, 1536
So if I were to upgrade the the rear shock the handling would be better? Do you think the frame, swingarm and rear wheel are rigid enough to put 50-70 HP through? or that would be crazy and should I look for little bit bigger bike

Thanks for ICE review that lets me know how it may perform from that standpoint. Thanks for the pictures as well

Richard230
24 January 2011, 1626
The frame looks like it could handle a GSX-R engine. That thing is really strong and stiff. The swing arm though and the forks are not so great. The wheels and tires are kind of lightweight and the brakes are just so-so. The frame is really too small to install both an electric motor, as well as batteries. That is why my son-in-law was planning on using a hub motor in the rear wheel. In my opinion, the only part of the bike that would stay in alignment if you put in a motor that made 50-70 hp would be the frame. Everything else would get bent.

Nuts & Volts
24 January 2011, 1709
Thanks Richard. Then it looks like I will most likely hold off on one of those bikes. The ones I was looking at were the Derbi frames but they look pretty much identical.

jazclrint
25 January 2011, 1644
Ummm, just thinking out loud but . . .

Where Nuts is just looking to upgrade from an electric bicycle, wouldn't a single Agni and a 2 kwhr pack do nicely. It would make for a stupid light package, which would help range and acceleration. And maybe using headways or turnigys would help in creative battery placement? As far as forks and swing arm, if your chassis is still, then you can upgrade those other things. Maybe forks and swing arms from other Aprillia bikes might fit.

Nuts & Volts
25 January 2011, 1701
Ummm, just thinking out loud but . . .

Where Nuts is just looking to upgrade from an electric bicycle, wouldn't a single Agni and a 2 kwhr pack do nicely. It would make for a stupid light package, which would help range and acceleration. And maybe using headways or turnigys would help in creative battery placement? As far as forks and swing arm, if your chassis is still, then you can upgrade those other things. Maybe forks and swing arms from other Aprillia bikes might fit.

Agreed that would be one light beast.

But to clarify I wanted the aprilia in ICE form for the next 5 months. This would supplement extended range (ebike=15 mile max) so I can travel farther. Then when i return home (ohio) I would convert the aprilia to an electric ride. Basically this would give the best bang for the buck.

I think I have decided to pass on the aprilia rs50 due to its lower end suspension. A 125 or 250 would fit the bill better.
Something like this may be a good fun fit, any thoughts on a hyosung GT250R??
http://sfbay.craigslist.org/eby/mcy/2177697621.html

jazclrint
25 January 2011, 1744
Well, I haven't kept up with the current ICE bike market like I used to, but Hyosung's 650 was basically a cheap copy of the Suzuki SV650. I fear the parts on it would be even worse than on the RS50. But I cannot say for sure.

Nuts & Volts
25 January 2011, 1820
watched and read some reviews on the hyosung. good performance for a 250, but it is not built very well and thus wouldnt hold up very well. I have seen that the engine is good thou. I hold off on one of those most likely

Richard230
25 January 2011, 1857
I have only seen one Hyosung 250. It sure was heavy. Especially the wheels and frame. They appeared to be the same ones used for their 650. To me, $2000 seems too much for the bike. I think it sold new for around $3000.

I bought a 250 Ninja a few years ago and it only cost $2800 brand new. I gave it to my daughter and it is still running well. I think it has around 25,000 miles on it so far. I was able to get it up to an indicated 100 mph and I have been very impressed with the bike. My daughter loves it and even her husband will sometimes leave his VFR800 at home and ride the Ninja into SF to commute to work. Unfortunately, I get to maintain the bike and I really hate to adjust the valves as it is a lot of fiddly work. I would suggest looking for one of these. There are plenty around and the engines tend to wear out rapidly without constant and dedicated maintenance. You might be able to buy one with an engine on its last legs and then junk the engine and do your build. There is more than one electric 250 Ninja running around, I have heard.

Tony Coiro
25 January 2011, 2124
Yea, I really like the 250 ninjas if you can find one. Although the first bike I rode was my electric conversion, the first (and only) gas bike I have ridden was a 250 ninja and I had no problems with it.

Nuts & Volts
26 January 2011, 0917
Yea the ninja 250s are a viable option. I just dont like the styling of the older models. I would be happy with a newer model. I'm in no hurry so ill keep my eyes open for a deal on something.

Remotecontact
26 January 2011, 1222
Yea, I really like the 250 ninjas if you can find one. Although the first bike I rode was my electric conversion, the first (and only) gas bike I have ridden was a 250 ninja and I had no problems with it.


LOL I was there!!!!

Tony Coiro
26 January 2011, 1512
LOL I was there!!!!

Haha yup, it was pretty incredible. I got on the bike and I'm pretty sure I heard angels singing. I don't wanna say I am the greatest motorcycle rider of all time (but I am.) :D

Nuts & Volts
26 January 2011, 1533
Remote any idea what your ninja weighed naked (ie frame, suspensoin, wheels)? Just curious

Remotecontact
28 January 2011, 2224
Remote any idea what your ninja weighed naked (ie frame, suspensoin, wheels)? Just curious

Really have no idea but I'd guess a bit over 200lbs.

Richard230
29 January 2011, 0813
I can tell you that a stock pre-2009 250 Ninja, fully gassed, weighs about 350 pounds (the new model weighs more). I will guess that removing the engine, exhaust system and other miscellaneous IC stuff would cut about 100 pounds from the bike. My Aprilia RS50 weighed about 280 pounds stock. I was surprised how light the motor was when I removed it. I think it weighed about 35 pounds and the rest of the IC junk added maybe another 15 pounds. I don't think you are going to find a rolling motorcycle chassis, that can handle the weight of an electric build, that will weigh much less than 250 pounds.