2 Stroke E-chaser

Respect of Lipo
To begin, electric is rather clean, just ride and plug in afterwards. Later when you walk by, unplug and disconnect the charger. Ride, repeat . . . If you know what you're doing, life is good.

Know what you're doing concerning lipo. So here are the basics of lipo;
1) cells charge to 4.2volts; a 5S batt has 5 cells and charges to 21volts,
2) nominal is 3.7volts per cell, a 5S batt (lipo brick) is said to be 18.5volts,
3) full discharge is 3.2volt per cell, shouldn't run below 16volts, never run below 15volts or 3.0volt per cell.

The lipo runs well from 4.2V down to 3.7V or perhaps 3.5V. It "sags" to 3.7V and is said to "go over the cliff" a little below that. Around 3.5V the voltage level dives when throttle/load is applied and will deplete itself rapidly to 3.2V per cell. For this bike, the controller LowVoltageCutoff (LVC) is set at 64volts. All power shuts down whenever the batt pack drops to 64V(20S) thus safely letting you know it's time to recharge.

Charging: 3 chargers optimal; 1) 6amp fast bulk, 2)3amp medium bulk, & 3)low wattage lipo balance. (plus a small batt tester) See foto3 below.
At the track, 1)fast charging is needed when there's only 1 batt pack. The downside is that relying on fast charging will result in shorter batt life and eventual lipo swelling. Other times 2)taking a few hours to charge is best. And 3)balance charging is necessary whenever cells, within a lipo brick, vary 0.25volts from each other; every other charge to every half dozen charges, depends. Less than 0.1volt variance is ideal. As there's not much time for charging trackside, balance charge the day before raceday. See small lipo batt tester in fotos.

The lipo bricks can get further out balance from each other, I've allowed 0.5V for this. Foto1 is at 20.36V (again cells are well within 0.1V; 4.05V to 4.08V). Foto2 the lipo is at 19.95V (though the 5cells are nicely balaced at 3.96V to 4.03V) Yet the low and high lipos are 0.4V apart. This is typical and OK to ride. Use the small (green Venom) balace charger to boost the low lipos when they are 0.5V apart and the day before a race.

Standard Operating Procedures SOP
1)If you're not experienced with Lipo, charge outdoors only, not in your house.
2)Disconnect only 1 pair of power wires at a time and only if necessary, such as when balance charging. Reconnect those before disconnecting the next pair.
3)If you are working with or changing connectors, keep any bare leads electrical taped.
4)Keep a fire extinguisher on hand.

Foto1 19.96V lipo Foto2 20.36Vlipo Foto3 Lg black 6amp, med black 3amp, & green balance chargers.

Not fast enough. 41mph topend is good, but can't stand seeing others pull 10-20feet on me coming out of turns.

With 45amps, there's a motor stutter accelerating out of corners, (likely the sensorless controller struggles to provide 40+amps@74V), and motor temp(coil) is cool enough to bump amps up to 50A. Lyen is working his magic as I type. If done before Thanksgiving, I'll give it a test run, maybe get a 2nd rider to verify.

Here is a shot of inside the controller mid-job. Small copper wire is laid along the traces then soldered over so the unit can handle the higher amp/current. Also a larger resistor shunt is going in plus larger capacitors. As of now, when I plug in controller to batt pack, there's a pop 'an arc from the 84volts. Not a big problem, yet 1 pair of connectors tend to get sooty/blackish from the arc. The pre-charge Lyen is laying in will tame down the 'arc' so the connectors can keep a clean connection.
http://lyen.com/

Conclusion Summary of Electric Bikes in MotorBike Racing

With a big 'nough hunk of copper/iron, over powering the competition is a given (Our Pioneer builders have overcome formidable challenges; Congratulations LFP & Farfle) Same for Hubzillas/CroMo's ect. . . A properly set up Crystal HS3548 in 20" might have potential to podium. The oversized 28 & 40horsepower e-motorcycle guys impressed a following of e-bike builders, yet some of the core gas racers hold an opposite view.

PaulD's winning was the combination of a true and equitable build combined with refined riding skill; with a tiny boost from weighing <150lbs. His RC 6K dazzled the crowd at TucsonDR and repeated at Grange 4/7, demonstrating that 6K input suffices to compete against 11hp gas bikes. The RC electric build is not a slam dunk for the average builder/racer. Most folks DNF in this somewhat sophisticated build category. (Congrats to Stevil Knevil 2nd mid-class/Grange & Etard for winning heat1 Adams) If I were to build this type racer again, I'd use the Turnigy130 and attempt 1 stage gearing, an itsy bitsy 8-10T #25 drive sprocket with a tensioner sprocket that helps wrap around extra teeth: #25 chain back to 60T bicycle chainring modified to 120T.

Front/rear dual hub could be the ticket. 2X's Mac's 25Arear/20Afront, that's only 2.5K@15S would be competitive with most low power bikes excepting 'shuttlebuddies' and 'nuvinci' driven builds. Of course dual 3+3K(3.5+2.5K) hubbies could challenge the 11hp racers IMO.

At Adams, this 3K 9Cont fell in no man's land. Not lapped by modded ChinaGirls, but able to lap stock ChinaGirl setups. Bumped the controller up to 45amps (3.4K), found my self running in the mid-4strokes at Grange, pedalling all 12 laps squeaking 3rd out of 11 racers!

If there's has to a number to hammer down, 2 gas horsepower equates to 1 electrical (nominal) horsepower due to a graciously broad power band applied to single speed racers. Yell at me if you want. If electric wants to earn the respect of competing with gas, <=6K is a realistic pragmatic power limit to compete with the 11hp class.

In 20/20 hindsite: Would've put energy into air cooling the modest 9Cont2805 wind in 20" and adapted rear dropouts so a 26" wheeled bike could run the 20" wheel. With the 20" 9Cont; an adapter to move the rear drop out downward would be needed, or the bike becomes a uni-task racer, not suitable for fun/transportation riding. [Or, strapped a mid-size Crystal HS2440 up front (dual motors). Then the acceleration would've been pretty potent with mid-40s topend; still <5K and good to go in the 2stroke class: 4.65hp X 2 = to 9.3gas hp (@18S/65A)]

**Though at 1st, the pricey 'Green Cruiser' was selected because of a roomy area for the batts. I now can see ways to build the batt box onto a Target Dept Store Schwinn 26". For 1) to keep the total cost down around $1250. And for 2), I like to pedal, comfortably. http://www.target.com/p/schwinn-men-s-ranger-26-mountain-bike-red/-/A-13241029#prodSlot=medium_1_2

Regrets: only that they're weren't others sticking it out to get the e-racing sport viable. I can see affordable $1200 to $1400 e-racers that can fairly contest the slightly pricier ($1,500+) though fiercely competitive 2 strokes. E-race bike builds are doable by most do-it-yourselfer types. Additionally, they'll run reliable, race1, race2, giving years of service.

Motored bike racing is a free man's(women's) game. No corporation or government micromanaging the scene. You can dream it, put your sweat, blood, and gears into it, and test/prove yourself on race day. It's an exciting pursuit. I just hope it hasn't come to: We (electrics) came, we sqabbled, we fizzled.