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2 Stroke E-chaser

Posted: Jul 22 2012 2:25pm
by SoSauty
August, time to vamp up our race bikes! The E-crowd is talking up Sept15 as ‘the world championship’ of motorized bikes. I even heard there was some crazy guy driving down from Michigan. So, a day to build, a day to post, here goes:

For me, running mid-pack with a tire just in front, someone else’s tire under my elbow, is more fun than leading a race if out in front alone. So I’m bumping this mid-size 9-Continental 2806 to its’ limit (maybe beyond); gonna chase me some peppy 2 strokers (and Etard).

Issues: Replaced the dead headset and bouncy pogo forks with CaneCreek and RockShox forks on sale, $25 & $110. The fork was still too springy so set the lockout halfway; works. Also upgraded the mechanical front disk brake with a sweet ballbearing activated Avid B5.

Day1 Intro & safety upgrades

Day3 Modding the rear drops

Day5 Gearing, trueing, protection, reroute shifter cable, spacing

Day7 Beefing up motor phase wires

Day9 Amped up controller & connectors

Day11 Electric calculations, fancy batt box, tucking lipo harness

Day13 Tire selection (hope to uncover a surprise)

Day15 Lap times/impressions at Adams Kart track

Day17 Speedometer (bye bye CA), lights/reflectors, squirrel tail

Re: 2 Stroke E-chaser

Posted: Jul 24 2012 8:45pm
by SoSauty
Day 3

There’s to be some robust power with 100% of the torque getting transmitting to the axle. A spinout can result in ripped out electrics and a discharged rear wheel, dangerous! Turns out the wide spacing of the Chinese 150mm dropout is perfect to build in torque arms (without arms!) as part of the rear drop outs. A long 5/8” black chainring bolt replaced a shorter ¼” chrome shifter hanger bolt. Both sides have 3 screws and ample 3M DP-460(no sag) epoxy securing the aluminum inside the dropout zone. There’s now an added ¾” to clamp the torque and achieve spacing.
3/16ths X 2
R-C9Mod11.jpg (237.05 KiB) Viewed 875 times
3M 460 Epoxy
R-C9Mod12.jpg (229.69 KiB) Viewed 875 times
3/4" more grip

Re: 2 Stroke E-chaser

Posted: Jul 26 2012 3:30pm
by SoSauty
Day 5

The 53T front ring and 13T rear sprocket enables pedaling out of turns. (29mph@100cadence)
To remedy sluggish shifting there’s trimming, shaping, and rerouting of the cable. Now it’s 5th gear off the line and quick click to 7th. Going from 6speed to 7speed freewheel helped center the wheel. After much obsessive tweaking, the interwoven 2cross Sapiem 13ga spokes yield a strong and <1mm true wheel. ¾” painted pvc with hose clamp provide protection for the motor wires exiting the axle.
6' of Covered Cable & 53T Chainring
Soldering Frayed End of 4' Cable
PVC Protector Left Axel End, 7Speed 13T Freewheel

Re: 2 Stroke E-chaser

Posted: Jul 26 2012 3:39pm
by docnjoj
Now that is a dropout! Wow!

Re: 2 Stroke E-chaser

Posted: Jul 26 2012 7:44pm
by Philistine
Where does the frame come from?

Re: 2 Stroke E-chaser

Posted: Jul 27 2012 4:51pm
by SoSauty
Philistine wrote:Where does the frame come from?
Keep in mind that components are pretty cheap; seat, seatstem, chainring, headset, controller ect. . . I probably ripped 'bout 20' of wiring out of it. Nice shifter, throttle OK, good spokes, itsy bytsy motor good for 16mph@15A.

Re: 2 Stroke E-chaser

Posted: Jul 28 2012 3:23pm
by SoSauty
Day 7 beefing up motor phase wires

In peak performance situations, one electric weakness is hot motor phase wires. Getting 12ga wires thru the axel was a challenge which I botched. In the struggle to fit 12ga I removed a clear layer of insulation. When trying to force the wire thru the inner insulation split exposing the copper.

Wimpy me opted for 14ga to replace the stock 16ga. At the time, I wasn’t sure there was a quality non-sensored controller around. So in hindsight, I could’ve pulled out the 5 tiny hall sensor wires and inserted the 3 beefier 12ga motor phase wires with the sensorless controller I've now decided to go with. I'll be noting the temp of wires at the track.

Once apart, the wires attach right out on top out in the open. Careful putting the side cover back, the magnets are powerful enough to decapitate a finger as it closes.

Two regrets: 1) modest 14ga rather than 12ga and 2) could've machined out the slit in axel from 1/2" to 1+" (eliminate the need to cap the axel with pvc, there is plenty of axel protruding on the left side where the motor wires exit)
Opening the 9 Continental
14ga upgrade

Re: 2 Stroke E-chaser

Posted: Jul 29 2012 7:12am
by dogman dan
Looks like a perfect build to run mid pack yet still smoke stock 50cc kit bikes easily.

Just don't lose your temper like I did a few years back. That duel with the guy in the white kawasaki shirt I got sucked into cost him the main event, when I got mad and made a move that crashed us both. I had him on the straight, but he kept outbraking me. Back and forth we went till I lost my brains and laid it down right into him.

Easy on the watts. I think I proved that a 9 c won't quite finish a long heat at 110v 40 amps. So save it for the main even if you have to run slow in the early heats. CO2 fire extinguisher to fast cool between heats? Dry ice?

I'm getting stronger, but dang it, September is prime time hot air balloon season. I hope to reappear on the track for one of the spring races, with the same ol bike but rear drive, running mid pack. Let's rub some elbows then eh?

Re: 2 Stroke E-chaser

Posted: Jul 29 2012 2:20pm
by The fingers
I don't fret over the occasional noisy stinker illegally using the river trail, once in a while the police/sherriff make a pass on a lazy afternoon and weed out the motorbikes, scooters, dip netters, and homeless. I just hold my breath when they go by till the fumes dissipate. What's really cool is to pass one doing the walk of shame/pedal of pain. 8) Go get 'em! :wink:

Re: 2 Stroke E-chaser

Posted: Jul 29 2012 3:57pm
by itchynackers
I've done a handful of phase wire upgrades, including 2 10awg upgrades. What I've found is this...drilling the axle out with a 5/16" bit (carefully with lube) and then filing the sharp edge on the inside of the axle (take a look in there) makes things easier. Also, while putting the new wires through, use some lube (chain wax, etc.)

Re: 2 Stroke E-chaser

Posted: Jul 29 2012 4:56pm
by SoSauty
A pleasure Dogmanz, We'll race as senior racers and both finish upright. One of the novice moped guys T-boned me at Grange. I was so surprised that I didn't try to put a foot out, just thought I'd slide a little and regain control. He caught me straight on right behind the BB so my elbow/hip contacted the asphalt 1st. It was just a heat.

Actually your front motor seems to have the cornerning advantage. I'd have to chase you. Yep, holding 'er down to 20S/40A/3K, also think the Adams race is a bit shorter, sub 15min as the track is only .6 mile so hope to not overheat. Even 'blue ice' might cool as we have 45min+ 'tween heats, 1hr+ to main. The real Adams race is under the lights and maybe it'll be cool by the October Grange event. Yeah, I just expect to run with the pack, but the fastest 2 stroker, here in CA, is dropping out and Etard(Dave) is still crashing or breaking. If you, Dave31 and Alex don't show up, I could land a top 5 :wink:

Kinda enjoy the smell of 2 strokes, it's their expansion chambers that ruin my serenity. Really love the reassurring whirl sound of our electrics. I usually sneak up on country dogs till they have to play catch up. Hate to mace a good guard dog. Ride 20-25mph, sub20mph on city bike path, pedal easy like, and wear a bike helmet, not a motorcycle helmet and have had no problems. Yeah, Bakersfield just built nice shelters for the homeless along their Kern River path. A sidewalk runs a 100' off the path to a covered shelter with picanic table and a nature billboard under Lexan glass. Pretty nice, gives me a place if my wife says, "Get out :P "

Itchyknackers, thought about milling the axel, but nervous about weakening it. Might mill the axel 19/64ths and redo with 10/12ga later. Gonna give the 14ga a try and check it's temp. I'm glad you've done it, gives me confidence to try.

Re: 2 Stroke E-chaser

Posted: Jul 29 2012 5:22pm
by dogman dan
My bikes gone rear now, so as to have a way to get at least one lame mechanical disk on the bike.

Likely to be run at 20s 40 amps, so as to avoid needing good brakes so much. :lol:
Race bike, halloween 2011.jpg
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Most likely won't show till next spring though. Love the sound and smell of the gassers. But love having electric on the start line, passing a few in the first 50 feet is fun.

Re: 2 Stroke E-chaser

Posted: Jul 30 2012 6:22pm
by SoSauty
I’ve pushed the lyen 6FET controlled to its’ limit, 30A up to 84V(20S), maybe as high as 2.5K off the line at the June16 Baird race. For 40Amps, Ed (Lyen) sent me his MarkII 12FET sensorless controller housed in a bigger box; can you say bigger ‘heatsink?’ Though I'm suspious above 35A for the modest 9C is getting into diminshing results.
Top 12FET sensorless MarkII set 40A; Lower 6FET senorless @30A
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Lyen has been a reliable person to do business with.
Tiny JST connectors for throttle
I’m fitting all my controllers with the same connectors: Andersons for the power as they are practical to plug/unplug 1,000s of times; tiny hard to see JSTs for the 3 wire throttles. The blue painters tape is to hold down the stout Radio Shack velcro 'till the 3M DP-460 epoxy sets.
Epoxy the velcro (Doc's 3M 460)
I'll be getting into the lipo, and simulator calculations later this week. Building the batt box might take a few days.

Re: 2 Stroke E-chaser

Posted: Aug 01 2012 11:34pm
by SoSauty
The 4 5S 8Ahr lipo bricks can power 12-15 racing laps but voltage would sag below 64V. Another 4 smaller 5Ahr bricks should keep the voltage up to 68volts to the checkered flag. The 4 5S 8Ahr lipos are in series for nominal 74V just as the smaller 4 5S 5Ahr lipo bricks are. The 2 series packs will be connected in parallel for 13AmpHr of power at 20S/74Voltage.

Though I'd see 3K+ spikes approaching 4K, a more stable and realistic power level would be:

Fresh charge 84Volts; under load 76Volts: motor power 2388/750W= 3.2 h.p.
After 12 laps 76Volts; under load 68Volts: motor power 2134/750W= 2.8 h.p.
Average = 3 electrical horsepower

I'd love to find out I could push a little more power (?45A) and not melt down in 15min :!:

Pic1 The batt box challenge:
4 lipo in center are 5S 8Ahr; the right-n-left pairs are 5S 5Ahr
Pic2 Not sure if this helps but these lipo bricks are paired up in series to double the voltage up to 45V. Then the pairs are connected to other pairs in parrellel to increase the Amperage. Hope to have this diagrammed this weekend.
Lipo pairs in Series; Pairs connected to other pairs in parrallel
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Re: 2 Stroke E-chaser

Posted: Aug 18 2012 4:27pm
by SoSauty
Drilling lexan takes time; it melts
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The batt box challenge is coming together;
1 soldered bullet connectors onto controller,
2 shortened lipo power wires as needed
3 padded lipo brick from box,
4 added shrink tubing to wires traveling between the lipo,
5 screwed and epoxied 3/16" lexan/1/16" 7075 aluminum,
5 cut/epoxied velcro strapping.
Just needs a little reinforcement
Still a mid-size lipo pack
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Weight is 16.4lbs close to 2lbs per brick & 0.4lb for light thin walled box. Dropped the box from 30" on its' corner several times. Note the red oval on bottom. The box wedges perfectly into the frame. With only 2 straps and 1 plastic tie, it'll remain solidly fixed and would be tough to dislodge when I crash.

Time spent building this box has taken almost half the time of entire bike. Don't know about you, but building a motored bicycle is pretty enjoyable.

Gonna look it over for safety, see if I can reinforce a bit.
Yep, takes time yet worth the safety
And the batt box is finished. This took a really long time, partly cause of our heat wave but more importantly, my remark about just a single plastic tie latching the world's highest energy density available to the public, in place, got me to thinking. After my big lipo pack flamed last October at Grange, figure my reputation can't take many more hits, and why not be safe?

Added 2 small reinforcers, tiny #2 screws 'an epoxied slivers of sheet aluminum. Several packs of velcro squares, mixed a bit of super glue with the adhesive backing, provided padding plus you could hold the bike upside down and the lipo bricks would stay put. Found a spot for another small plastic tie. A little electrical tape on corners, super glued, on some of the corners. It's been an honest effort to make the lipo safe.
Solid, sturdy, not to heavy
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The build is all downhill from here. Install tires, slap it together and ride. In pic below notice the big plastic tie top of center box wrapping around the seat tube, maybe a' hold 100+ pounds.
plastic tie rated 150 pounds

Re: 2 Stroke E-chaser

Posted: Aug 24 2012 4:55pm
by SoSauty
Settled on the Schwalbe Big Apples as they were closer to being slicks than the Kiniptions, though both look good. Both the stock tires and the BAs are stated to be 2.15". The stock ones measure 1 & 13/16" wide with a diameter of 24". The BAs measure 2 & 1/16" wide with a diameter of 24 & 3/8", good for an extra 1/2mph top end 8)
Sleek bike with Big Apple tires
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They have some flat protection and along with some pretty thick thorn resistant tubes, I can trust 'em.
Front View
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Didn't realize how sleek this build would turn out. The wheel, chain, and brakes aligned perfectly. But check out how close the tire comes to the battery support bar now. There's 1/16" (2mm) to spare :shock:
Tight Fit
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I've got a Century run coming up Sept 1st (other bike) but am charging right now. Should get time to take it for a spin 'round the neighborhood Sunday 8/27. Plenty of time to get out to Adams before Baird's 9/15 race event.