View Full Version : 2008 GPR-S Review

31 August 2010, 1512
It is time to fatten up the GPR-S forum on the new version of El Moto. Here is my previous article about the 2008 GPR-S that I owned for three months. It was a nice bike - until the BMS suffered a melt-down.

I have always been interested in old motorcycles. Over the past 50 years I have managed to accumulate four storage boxes of motorcycle road tests and factory brochures covering production motorcycles built since 1930. I believe that we are living in the beginning of the electric vehicle era and in an effort to assist future historians I have prepared the following owner’s review of the first practical freeway-legal production DOT-approved electric motorcycle manufactured in the United States. I have updated my comments with the help of hindsight and what I have learned over the past few months on the El Moto forum. The following comments represent my experience and best recollection regarding the 2008-model Electric Motorsport GPR-S that I purchased last year and have since replaced with a 2009 GPR-S 72V sepex version of this motorcycle.

In August 2009 I purchased an electric motorcycle. It was a 2008 model production Electric Motorsport GPR-S, manufactured in March 2009. I bought it from the Electric Green Showroom in San Carlos, California, a block north of the Best Buy store which now sells the Brammo Enertia in the Bay Area. The store had been open for about 6 months and I was told that my bike was the third GPR-S they had sold to date. The 2008 model is powered by a Briggs and Stratton Etek-RT permanent magnet motor, according to the EMS web site, with a claimed momentary peak power rating of 19 hp, but actual continuous maximum power was around 8 hp, based upon the bike’s real world performance on the street. My bike had a 60V (nominal) system, powered by 20 Hi Power LiFePo4 prismatic batteries, installed in 5 open-topped metal boxes, grouped four 3.2V cells to a box. The battery cells were connected in series and this model had a “spaghetti” type battery management system (BMS) where each cell was connected directly to the BMS computer that attempted to keep all of the cells balanced to an identical voltage as they were charged and discharged. The brain of the outfit was a 72 Volt, 300 Amp Alltrax Controller.

An announcement from Electric Motorsport in the fall of 2008 regarding the start of their firm’s production of electric motorcycles was described as follows: “The Electric Motorsport GPR-S is the first DOT compliant, street legal electric motorcycle capable of doing Freeway speeds. The Electric GPR-S is a Joint venture between Electric Motorsport and Tiger Motors. Tiger Motors builds the Electric GPR-S chassis exclusively for EMS. Final assembly is at the EMS facility in Oakland California”. Tiger Motors is a small motorcycle manufacturer in Thailand that builds a range of 50cc to 250cc motorcycles and an Asian version of the GPR-S called the e-Boxer.

During the first month I rode the bike some 200 miles, mostly back and forth to work. I was quite satisfied with the bike’s performance. A top speed run on the local freeway netted me a speed of 62. The bike ran right up to this speed and just would not go any faster. I believe that motor was limited by its maximum rated rpm and the gearing of the final drive. The maximum draw that I saw on the Cycle Analyst screen was almost 200 amps at around 50 mph, which seemed to be very good performance from the bike’s 20 Hi Power 50Ah batteries. The bike accelerated slowly upon starting from a stop when going uphill, probably due to the controller’s programming. But once you got moving, it would climb any hill and could keep up with expressway traffic – at least up to 60 mph. The throttle response was a little spastic, with noticeable surging on level ground (sort of like my old 2000 R1100R), but I got used to it after a while. The standard model GPR-S does not have regenerative braking, so going down the many hills in my area meant that my brakes got a workout, but they performed quite well. The Tiger brakes, which appear to be a copy of 1980’s era Brembos, seemed to be up to the task though. Going downhill uses no battery power, which is helpful. I liked the very low running noise and lack of vibration.

The quality of the GPR-S chassis is only fair, compared with the other modern Japanese and European motorcycles that I own. Everything is made in Thailand, of course, even the 90/80-17 front and 100/80-17 rear tires. The rear shocks appear to be stylized copies of Ohlins piggybacks, but of course they don’t work as well. The springs were way too stiff for my weight and the stiff springs overwhelmed the rebound damping of the shocks. Everything on the bike is made of either aluminum or plastic, except for the main frame, motor and battery boxes. The front suspension is sort of cute. It is an Ohlins upside-down fork look-a-like, not exactly something needed on this bike and the travel is quite short, maybe about 4”. However, the suspension and tires work just fine within the performance envelope of the bike and support my 145 pound weight with no problems. But again, the forks were over sprung and under damped, which made for a bouncy ride on a rough road. The heavily-braced aluminum rear swing arm was particularly impressive. The bike has a rated carrying capacity of 560 pounds! (This is more carrying capacity than even my BMW R1200R is designed for.) Although I imagine that this carrying capacity is tested every day in South East Asia where Tiger motorcycles are normally sold and are used by their owners to carry huge loads and sometimes entire families every day.

The Electric Motorsport GPR-S is a lot of fun to ride in light traffic. Its light weight of 280 pounds and low center of gravity (due the low placement of the motor and batteries) makes the bike very easy to ride, although the seat is a bit narrow and legroom on the bike is tight for a typical American male. It is slightly smaller than a Kawasaki 250 Ninja and has almost exactly the same performance as a current-model Vespa 150 motor scooter, but the GPR-S handles and rides much better than the scooter and goes up hills without slowing down.

A full recharge, using the bike’s EMS-brand 72 volt, 8 Ah on-board charger, took about 4½ hours. My ride to work was 10 miles and I had to go up and down three long hills to get there and back at expressway speeds. I typically used about 15 AH in each direction while keeping up with traffic at around 50 mph. The manufacturer recommends not using more than 80% of the 50 Ah battery capacity, or 40 Ah before recharging, in order to get maximum life out of the batteries. The batteries are rated by the manufacturer as being able to accept up to 2500 charges before needing replacement. That is a lot of riding when you are pretty much chained to a 15 or 20-mile radius.

I had no problems insuring my bike, other than I was told that this was the first electric motorcycle that my insurance company had insured. Because I own so many motorcycles, have a clean driving record, am over 62 and only have them insured for liability (being self-insured really saves me a lot of money each year on the other 6 motorcycles that I own), the GPR-S only cost me an extra $5 (!!!) per year to insure. What a bargain!

This is the perfect vehicle for commuting to work, if your work place is not more than about 15 or 20 miles away. At my workplace I can park my bike next to my office window and run a 25 foot extension cord, connected to my desk outlet, out the window to “refuel” the bike for a worry-free full throttle trip home.

Unfortunately, my GPR-S met an untimely “death” after only 300 miles of riding. I decided to try for a maximum performance run to the local shopping mall. This involved a full-throttle run on a freeway for 10 miles and back, which included a 3-mile long 6% hill. The GPR-S performed really well on this ride. It was able to go up the freeway hill at 55 mph, which was exactly the same speed that my 1969 Yamaha 350cc YR2-C would climb that same hill in top gear at full throttle. By the time I returned home, I had used 37 Ah and the batteries were starting to sag a bit. I plugged in the on-board 8 amp charger and recharged the batteries. During charging I noticed the smell of burning insulation, although charging proceeded normally. However, after my next ride the charger would no longer work. The problem was ultimately found to be a toasted BMS and was apparently not something easy to repair. Eventually, I sold this bike back to EMC for a new 72-volt, 50 Ah Sepex model GPR-S, which I purchased in January 2010. This version of the GPR-S has a new design BMS and has been functioning well over the past nine months and over 1200 miles of riding around town and commuting to work.

31 August 2010, 1841
Here are photos of my 60 V 50 Ah 2008 Electric Motorsport GPR-S: