PACE Kalo Grant
UH Mānoa's Pacific Asian Center for Entrepreneurship backed the build with a Kalo Grant. Mahalo, PACE.
University of Hawaiʻi at Mānoa · Mechanical Engineering senior design
JIK
YeshuaBikes
Four ME seniors are converting a 1991 Suzuki RM250 to electric. On it we're building the Boost Tank, a gauge that shows the rider how many seconds of full power are left before the motor or controller gets too hot.
Executive summary
The project in one page
$2,268spent so far
$956of parts still to buy
Nov 30rideable, instrumented bike
70%+of surveyed riders have hit thermal limits
- Who
- Team JIK: four mechanical engineering seniors in ME 482 at UH Mānoa, advised by Dr. John Allen.Riley LauBoyd HagiharaAdrian RaveloCameron Austin
- The problem
- An electric motor can make far more power in a short burst than its cooling can carry away. The hottest parts heat up in seconds while the sensors lag, so controllers either cut power early or drop the rider into limp mode with no warning.
- Our solution
- The Boost Tank. An ESP32 reads motor current and temperatures, predicts how many seconds of full power are left, shows it like a fuel gauge, and only allows boost while the tank has room. It talks to the controller over its standard CAN port, so no custom controller firmware.
- The bike
- A 1991 Suzuki RM250 with a liquid cooled QS138 motor, a VESC controller, one coolant loop and a donated 72 V battery we're upcycling with a new BMS.
- Where we are
- Motor, controller, cooling loop, telemetry hub and a new BMS and charger bought. A local powersports shop donated a 72 V battery. Won a $500 PACE Kalo Grant. Bench tests start Nov 16.
- What we need
- $956.04 in parts to finish (full list on the BOM tab), plus testing and a spring 2027 phase. Department and college funds cover part of it. Sponsors fill the rest.
- Also looking for
- Time on a local dyno to test the bike. See the Donate tab.
- How to help
- Give through The 1112 Initiative Foundation (our preferred, tax deductible route), buy a part outright, or give through UH. See the Donate tab.
- Long term
- Rider trials at Kahuku over the winter, then the UH Venture Competition in spring 2027 with real ride data.
Where we are
Timeline
- DoneDonor bike, coolant loop, motor and telemetry hub in hand. A local powersports shop donated a 72 V battery. Won a $500 PACE Kalo Grant. Switched to a VESC controller (on its way) and bought a new BMS and charger for the battery.Done
- Nov 16 to 30Motor and controller bench tests on a loaned programmable DC supply, then battery tests.Up next
- Nov 30Rideable bike with the telemetry hub on board.Goal
- Dec to JanRider trials at Kahuku Motocross Park. Stock fixed-timer boost against our Boost Tank: cutouts, peak temperatures and boost delivered.Planned
- Spring 2027UH Venture Competition with real ride data.Planned
Already helping us
- Our department and college fund the core build parts.
- A local powersports shop donated a 72 V battery pack that wouldn't charge. We're bringing it back with a new BMS.
- A local engineering firm is loaning us a programmable DC supply.
- UH Electrical and Computer Engineering is lending an oscilloscope.
- A licensed power electronics engineer is mentoring our test setup.
Supporters
Who's backing the build
Your company here
Sponsors get their logo on the bike, our poster and our final report, plus updates on how the money was used.
The build
What's on the bike
- Donor
- 1991 Suzuki RM250Two stroke motocross bike, engine coming out
- Motor
- QS138 90H, liquid cooled4 kW rated, built-in reduction, chain drive
- Controller
- VESC Labs Classic+ 100VOpen source, current set live by the ESP32 over CAN
- Battery
- 72 V pack, upcycled from a failed batteryOn loan, testing in November
- Cooling
- Motor and controller on one coolant loopPump, radiator and fans from Golden Motor
- Brain
- ESP32 telemetry hubLogs temperatures, coolant flow, current and power to SD
- Display
- 3.5 in handlebar screenShows the Boost Tank and part temperatures
- Throttle
- Kickdown boostTwist past a click to ask for boost
How the Boost Tank works
Three steps, many times a second
Measure
Motor current, motor and controller temperatures, and coolant temperature and flow go into the ESP32.
Predict
A small heat model of the windings and the case turns current into the seconds of full power left before any part reaches its limit.
Gate boost
When the rider clicks for boost, the ESP32 raises the controller's current limit over CAN only while the tank has room, and shows the number on the dash.
Safety
How we test safely
The pack runs up to 84 V and well over 100 A, so every test follows the same rules.
Before any high voltage test
- A written risk assessment, reviewed by our department
- An approved test location
- Nobody works alone, ever
- A licensed power electronics engineer reviews our setup
In the power path
- 200 A Class T main fuse
- Anti-spark connectors and a precharge step
- A contactor on a key switch
- A lanyard kill switch that cuts power when pulled
Battery and bench
- Charged to 82 V max for testing, supervised
- ABC extinguisher and fire blanket on hand
- Regen off on the bench supply, motor clamped, chain guarded
- 1000 V insulated tools and an IR camera to watch temperatures
Photos
From the shop
Bill of materials · updated Nov 9, 2026
Every part, what it cost, what's left
Spent so far$2,267.80
Still to buy$956.04
Only if a check calls for it$449
Next phase, spring 2027~$250
Prices are list prices before Hawaiʻi tax and shipping. Department and college funds cover part of the list. "If needed" parts are only bought if a test or fit check calls for them. TBD means not priced yet.
Want to buy a part outright? Email us first so we don't double up, and we'll send the shipping address. See the Donate tab.
Spent so far $2,267.80
| Item | Cost | Status |
|---|---|---|
| 1991 Suzuki RM250 donor bikeWith stock radiator | $350.00 | Bought |
| QS138 90H liquid cooled motor4 kW rated, built-in reduction, incl. shipping and tax | $731.70 | Bought |
| VESC Labs Classic+ 100V controllerOpen source, 300 A, talks to the ESP32 over CAN. Replaces the FarDriver (returned, refunded). Incl. FedEx from Sweden | $375.28 | Bought |
| Telemetry hub partsESP32 x2, SD logging, clock, coolant probes, ADCs, flow meter, current sensing, energy meter, 3.5 in display, switches, encoder, harness connectors | $289.09 | Bought |
| Golden Motor liquid cooling systemPump, radiator, fans and converter, incl. shipping | $168.82 | Bought |
| Bench loop fittings and heaterTees, barbs, clamps, PTFE tape, 300 W immersion heater, reference thermometer | $76.61 | Bought |
| JK smart BMS (JK-BD6A20S20P)New BMS for the upcycled 72 V pack, 200 A, active balancing, Bluetooth. Incl. tax | $109.94 | Bought |
| 84 V 5 A battery chargerYZPOWER, for the upcycled pack. Incl. tax | $72.24 | Bought |
| Pack charge plugM23 2+1+5 waterproof plug set for the pack's charge port | $11.40 | Bought |
| CAN boardsSN65HVD230 transceivers, 2 pk (ESP32 to VESC, battery CAN). Incl. tax | $17.79 | Bought |
| Raspberry Pi Pico boards2 pk, CAN logger for diagnosing the battery. Incl. tax | $14.51 | Bought |
| Torx security bit setTo open the battery pack case. Incl. tax | $10.46 | Bought |
| FarDriver USB programming cableNot needed after the switch to VESC, being returned | $39.96 | Returning |
| Total | $2,267.80 |
Loaned, borrowed and on hand
- Traction battery72 V, 35 Ah pack that wouldn't charge. Donated by a local powersports shop; we're upcycling it with a new BMS and chargerDonated
- Programmable DC supplyBench power for motor and controller bring-up, Nov 16 to 30Loaned by a local engineering firm
- OscilloscopeThrottle, hall and noise checksLoaned by UH ECE
- IR cameraThermal images during testsOn hand
- Machine shop and 3D printerMotor plates, throttle collar, sensor and dash housingsUH shop
Drivetrain and high voltage $167.60 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| Red port mating plug (Gridpower)Connects the pack's red discharge port to the bike's 6 AWG run. Backup charge plug for step 7. | 1 | $25.00 | If needed | |
| Class T main fuse, about 110 to 125 AMain fuse on pack +. Protects the 6 AWG run. | 1 | TBD | If needed | |
| VOZINMOST Class T holderHolder for the main fuse. | 1 | $22.99 | If needed | View part |
| QS8-S anti-spark plugs, 5 pairsOn pack + and pack −. Unplugged means the bike is off. Swap point between the pack and the bench supply. | 1 | $29.99 | Needed | View part |
| BNTECHGO 6 AWG red + black, 3 ft eachPack + to fuse, fuse to QS8, QS8 to contactor, and the negative run. | 1 | $21.98 | Needed | View part |
| TKDMR 6 AWG 5/16 in lugs, 10Ends for the 6 AWG runs, VESC leads and the M8 0 V bolt. | 1 | $7.98 | Needed | View part |
| TKDMR 4 AWG 5/16 in lugs, 10QS138 phase lead ends. | 1 | $7.99 | Needed | View part |
| TEMCo hammer lug crimperCrimps the 6 and 4 AWG lugs. | 1 | $13.50 | Needed | View part |
| Hongfa HFE82V-300C contactor, 300 A, 12 V coilMain switch on pack +. The coil runs through the key and the lanyard. | 1 | $58.80 | Needed | View part |
| Qjaiune 100 ohm 25 W resistor, 2 pkPrecharge. Fills the VESC capacitors so the contactor and the BMS never see inrush. | 1 | $5.49 | Needed | View part |
| Ulincos 16 mm momentary buttonPrecharge button, in series with the resistor. | 1 | $7.88 | Needed | View part |
| Witproton 10 A PV fuse holderFuses the DC-001 input off the contactor input stud. | 1 | $13.99 | Needed | View part |
| 72 to 12 V 10 A buckFallback 12 V source. | 1 | $16.99 | If needed | View part |
12 V system $151.91 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| Blue Sea 5025 fuse blockSix 12 V circuits off the DC-001. Rated 32 V, so 12 V side only. | 1 | $31.16 | Needed | View part |
| ATO blade fuse kit, 60 pcs5 A coil, 3 A pump, fans and hub. | 1 | $6.59 | Needed | View part |
| Ignition key switch, 2 wireKey in the contactor coil line. | 1 | $8.99 | Needed | View part |
| Dual circuit kill lanyardCircuit 1 opens the contactor coil. Circuit 2 tells the ESP32. | 1 | $22.19 | Needed | View part |
| 1N5819 diodes, 100Flyback diode across the contactor coil, unless it has built-in suppression. | 1 | $7.99 | Needed | View part |
| DROK 12 to 5 V buck, 6 A5 V for the hub, TFT, SD and flow meter. | 1 | $17.99 | Needed | View part |
| 14 AWG red + black primary wireDC-001 yellow to the fuse block, and the 0 V bus to the junction. | 1 | $12.00 | Needed | |
| 18 AWG red + black primary wire12 V circuits and the precharge loop. | 1 | $10.00 | Needed | |
| Insulated ring terminal kit + ratchet crimper5/16 in rings for 18 to 14 AWG and #8 rings for the fuse block. | 1 | $25.00 | Needed | |
| 1 in 3:1 adhesive heat shrinkCovers the bolted phase splices and the 0 V junction. | 1 | $10.00 | Needed |
Signals and telemetry $172.11 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| Axiniu dual hall throttleTwist throttle into VESC AD1. 5 V hall, about 0.8 V closed to 3.8 V open. | 1 | $42.99 | Needed | View part |
| Weasch IP67 roller switch, 2 pkKickdown click at full throttle (boost request to the ESP32). | 1 | $12.99 | Needed | View part |
| HARFINGTON M6 ball plunger, 5 pkKickdown detent. | 1 | $6.19 | Needed | View part |
| Hydraulic brake switches x2Brake signal into VESC AD2 and the ESP32. | 1 | $15.34 | If needed | View part |
| DOT 4 brake fluidBleed after fitting the brake switches. | 1 | $10.00 | If needed | |
| Ceramic capacitor kit (100 nF)Kickdown debounce, ADC and CAN decoupling. | 1 | $14.99 | Needed | View part |
| 22 AWG 4C shielded cable, 25 ftCAN pair and probe runs. | 1 | $16.99 | Needed | View part |
| Ceedmon clip-on ferrites, 20On the throttle, hall and CAN leads near the VESC. | 1 | $8.99 | Needed | View part |
| Deutsch DT kit, 2 to 12 pin, with crimperBreak points so the hub, dash and motor come off without cutting. | 1 | $38.99 | Needed | View part |
| ADuM3160 USB isolatorLaptop to VESC Tool or the hub while 72 V is live. | 1 | $16.99 | Needed | View part |
| Arctic MX-4 pasteSurface probes on the motor case and pack. Tape them on, no glue. | 1 | $4.99 | Needed | View part |
| ESP32 lead for the JK data port (4 pin, 1.25 mm)JK BMS data into the ESP32 at 115200 baud. | 1 | $8.00 | Needed | |
| UGREEN SD card readerRead the SD logs on a laptop. | 1 | $8.49 | If needed | View part |
| CR2032 coin cellRTC backup. | 1 | $2.00 | If needed | View part |
Battery: BMS swap and charging $51.97 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| Kuject solder seal connectors, 120Splice the JK balance harness one wire at a time. | 1 | $9.99 | Needed | View part |
| Pangda fish paper, adhesiveInsulation under the BMS and over exposed busbars. | 1 | $11.99 | Needed | View part |
| MYJOR Kapton tapeTape exposed metal inside the pack. | 1 | $9.99 | Needed | View part |
| 2 cam straps + rubber padHold the pack in the cradle and keep it removable. | 1 | $20.00 | Needed | |
| M6 ring lugs for the JK BMS terminalsPack's internal B− and P− cable onto the JK's M6 studs. | 1 | $8.00 | If needed | View part |
| Second NTC 10k probeSecond JK temp probe on the middle cells. | 1 | $7.00 | If needed | |
| 15 A PV fuse + inline holderFuse on the charge lead. | 1 | $14.00 | If needed | |
| Neutral cure RTVReseal the case. | 1 | $10.00 | If needed |
Cooling loop $41.27 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| PATIKIL 40 x 120 mm cold plates, 2 pkSide by side under the VESC (107 x 72 mm), in series. | 1 | $14.29 | Needed | View part |
| Aairhut thermal pad 13 W/mK, 120 x 120 x 1 mmVESC base to the cold plates. | 1 | $11.98 | Needed | View part |
| 3/8 in ID silicone hose, 10 ftMore hose for the loop. | 1 | $19.99 | If needed | View part |
| Coolant, distilled + aluminum safeLoop fill. | 1 | $15.00 | Needed |
Mechanical $92.79 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| M8 x 30 grade 8.8 bolt kitPhase splices, 0 V junction, brackets. | 1 | $10.99 | Needed | View part |
| M10 x 40 grade 8.8 bolt kitMotor plates to the stock engine bosses (match sheet C1 to C3). | 1 | $13.69 | Needed | View part |
| M8 rubber isolators, 4Battery cradle mounts. | 1 | $9.99 | Needed | View part |
| 6061 plate, 1/4 in, 12 x 12 inMotor side plates. | 1 | $45.39 | Needed | View part |
| 6061 angle, 1.5 x 1.5 x 1/8 inBattery cradle. | 1 | $12.73 | Needed | View part |
| 520 13T sprocket for the QS138Front sprocket. | 1 | $49.99 | If needed | View part |
| 520 chainDrive chain. | 1 | $76.81 | If needed |
Tools and safety $89.39 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| Gunpla 1000 V insulated toolsInsulated screwdrivers and pliers. The SOP requires them. | 1 | $29.99 | Needed | View part |
| UNI-T UT210e clamp meterDC current checks: load steps, precharge, charger, VESC current. | 1 | $65.99 | If needed | View part |
| Wagner HT1000 heat gunLug heat shrink and solder seals. | 1 | $33.49 | Needed | View part |
| Kester 44 solderHub and harness solder joints. | 1 | $15.93 | Needed | View part |
| Pinecil V2 soldering ironSoldering iron. | 1 | $42.00 | If needed | View part |
| iCrimp SN-28B crimperDupont and JST crimper for small connectors. | 1 | $22.29 | If needed | View part |
| Wire stripper + flush cuttersPrep for every run. | 1 | $31.96 | If needed | View part |
| Fire blanketOn hand for every live battery step. | 1 | $9.98 | Needed | View part |
| ABC extinguisherOn hand for every live step. | 1 | TBD | Needed |
Testing and later $189.00 needed
| Item | Qty | Cost | Status | |
|---|---|---|---|---|
| Rider trials at KahukuTrack day fees and thank yous for test riders. | 1 | $189.00 | Needed | |
| PCM boost bufferWax block in the coolant loop. Spring 2027. | 1 | $250.00 | Spring 2027 |
Hand tools the team already owns (sockets, wrenches, drill, calipers) aren't listed.
Donate
Three ways to help
Every gift goes to parts, testing and the next phase of the bike. Mention "Yeshua Bikes" with your gift.
Give through The 1112 Initiative Foundation
The 1112 Initiative Foundation is a 501(c)(3) nonprofit, so gifts are tax deductible. Anything we don't spend this semester stays with the foundation for the next phase of the bike and future student builds.
- Online: email us and we'll send the giving link.
- By check: payable to The 1112 Initiative Foundation, memo "Yeshua Bikes." Email us for the mailing address.
- Receipt: we'll send our EIN and a receipt for your records.
Buy a part outright
Pick any item marked Needed on the BOM tab. Email us first so we don't double up, and we'll send the shipping address.
A part counts toward a sponsor level at its price.
Give through the University of Hawaiʻi Foundation
Prefer to give through the university? We're setting up a UH Foundation option for our project. Email us and we'll send the details once it's confirmed.
About The 1112 Initiative Foundation
The 1112 Initiative Foundation is a 501(c)(3) nonprofit and our preferred home for project gifts. Gifts marked "Yeshua Bikes" go to this build, and anything left over funds the next phase and future student engineering builds. We'll send our EIN with your receipt.
Have a dyno on Oʻahu?
We're looking for a local dyno to test our bike. A motorcycle chassis dyno (like a Dynojet) for a few pulls once the bike runs, or a motor dyno or DC load bank for our bench tests. It would show the real torque and power the Boost Tank is managing. We'd credit you on the bike, our poster and our final report.
Email us or call 808 308 5514.
Logo placement
Where your logo goes
Motocross bikes carry three number plates. That's where sponsors go. We'll confirm the spot and size with you before anything is printed.
- 1Front number plate · Factory $1,000+The biggest logo, facing forward in every photo of the bike.
- 2Side number plates · Podium $500+Both sides, under the seat.
- 3Fenders and shrouds · Holeshot $250+A smaller logo on the bodywork.
- PPoster and final report · Pit Crew $100+Your name on our sponsor list.
Sponsor levels
Get your name on the bike
Each level includes everything in the levels before it.
- Your name on our poster and final report
- A thank you in our build updates
- Your logo on the bike, poster and final report
- Build update emails as we test
- Your logo on a side number plate
- A shout out in our final presentation
- An invite to a bench test or ride day
- Your logo on the front number plate
- Featured in our final presentation and build posts
- We'll present the project to your team if you'd like
- Meet our team, resumes on request
After you give
What you'll hear from us
- Within a weekA thank you, plus a receipt if you gave through the foundation.
- Nov 16 to 30Build updates and photos from the motor bench tests.
- After Nov 30Results from the first rides, and where the money went.
- After Kahuku trialsThe A/B test results: stock boost against our Boost Tank.
Questions
FAQ
- Is my gift tax deductible?
- Gifts to The 1112 Initiative Foundation are, since it's a 501(c)(3). We'll send a receipt with our EIN. Buying a part and shipping it to us is a purchase, not a gift to the foundation. Check with your tax advisor for your own situation.
- What happens to money you don't spend?
- Gifts through the foundation stay there for the next phase of the bike and future student builds. Gifts through UH stay in that UH fund.
- Can I give a part instead of money?
- Yes. Pick any item marked Needed on the BOM tab and email us first so we don't double up. We'll send the shipping address.
- Can I see the bike?
- Yes. Email or call and we'll set up a time at the shop, a bench test, or a ride day.
- How do you use my logo?
- Only in the spots your level includes, and only after you send a logo file and OK the placement.
- Is this safe?
- Every high voltage test has a written risk assessment, an approved location, two people present and a kill switch. See the safety section on The build tab.
Contact
Let's talk
Email or call for giving details, the shipping address, photos, or a time to come see the bike. Mahalo for considering us.
Sponsor contactRiley Lau
Emailrileylau@hawaii.edu
Phone808 308 5514
Faculty advisorDr. John Allen, Mechanical Engineering, UH Mānoa