I purchased a 1981 Honda C70 Passport motorcycle today. I purchased the motorcycle on Ebay and since the seller was located in the same city, I paid no shipping. I would have preferred buying one cheaper in worse condition, but the shipping charges are a high percentage of the price. I will drive this motorcycle as is while I plan the EV conversion. I have found a good DC motor candidate at a good price. The good news is that this motorcycle gets around 95 MPG as is. That is one of the ironies of this motorcycle and one of the reasons it has been so popular. However, based on preliminary data, this vehicle will be even more economical after the EV conversion, especially when the new lower maintenance charges are factored in. I will present regular updates on this project as well as other projects that will be tackled.
Honda C70 Passport
Specifications
| Dimensions | Overall Length | 71.1 in. | 1805 mm |
| Overall Width | 26.2 in. | 685 mm | |
| Overall Height | 39.2 in. | 995 mm | |
| Wheelbase | 46.5 in. | 1180 mm | |
| Seat Height | 29.9 in. | 760 mm | |
| Min. Ground Clearance | 5.1 in. | 130 mm | |
| Dry Weight | 184 lbs. | 83.5 kg | |
| Frame | Type | Pressed & tube steel type | |
| F suspension, travel | Leading link, travel 2.2 in. (55 mm) | ||
| R suspension, travel | Swing arm, travel 2.4 in. (60 mm) | ||
| F tire size, pressure | 2.25×17-4PR, 28 psi | 2.25×17-4PR, 2.0 kg/cm2 | |
| R tire size, pressure | 2.50×17-6PR, 28 psi (40 psi when laden) | 2.50×17-6PR, 2.0 kg/cm2 (2.8 when laden) | |
| F brake, lining area | Cable, Internal expanding shoes, area 13.4 sq-in. (86.4 sq-cm) | ||
| R brake, lining area | Rod, Internal expanding shoes, area 13.4 sq-in. (86.4 sq-cm) | ||
| Fuel capacity | 1.05 US gal./4.0 l. | ||
| Fuel reserve capacity | 0.21 US gal./0.8 l. | ||
| Caster angle | 64 deg. | ||
| Trail length | 2.8 in./ 70 mm | ||
| Engine | Type | Air cooled, 4 stroke OHC engine | |
| Cylinder arrangement | Single cylinder 80 deg inclined from vertical | ||
| Bore and stroke | 1.850 x 1.630 in. | 47.0 x 41.4 mm | |
| Displacement | 4.4 cu-in. | 72cc | |
| Compression Ratio | 8.8 : 1 | ||
| Valve train | Chain driven overhead camshaft | ||
| Maximum horsepower | 5.0 BHP at 7000 rpm | ||
| Maximum torque | 3.9 lb/ft at 5500 rpm | 0.56 kg-m at 5500 rpm | |
| Oil capacity | 0.74 US qt. | 0.7 l | |
| Lubrication system | Forced and wet sump | ||
| Cylinder head compression pressure | 178 +/-7 psi at 1000 rpm | 12.5 +/-0.5 kg/cm2 at 1000 rpm | |
| Intake valve opens | 0 deg BTDC | ||
| Intake valve closes | 20 deg ABDC | ||
| Exhaust valve opens | 25 deg BBDC | ||
| Exhaust valve closes | 5 deg ATDC | ||
| Valve tappet clearance | IN-EX 0.0002 in. | IN-EX 0.05mm | |
| Idle speed | 1500 +/-100 rpm | ||
| Carburation | Carburettor Type | Piston valve (slide), 14mm (0.55″) venturi bore | |
| ID. Number | 1980 model: PB32A | 1981 model: PB32C | |
| Float Level | 0.42″ | 10.7mm | |
| Drive Train | Clutch | Wet, multi plate, semi-auto centrifugal type | |
| Transmisson | 3 speed constant mesh | ||
| Primary reduction | 4.058 | ||
| Gear Ratio 1 | 3.272 | ||
| Gear Ratio 2 | 1.722 | ||
| Gear Ratio 3 | 1.190 | ||
| Final reduction | 2.571, drive sprocket XXT, driven sprocket XXT | ||
| Gear shift pattern | Left foot operated return system, N-1-2-3 | ||
| Electrical | Ignition | Flywheel magneto | |
| Points Gap | 0.012 – 0.016″ | 0.3 – 0.4 mm | |
| Ignition Timing “F” Mark | 15o BTDC, Static | ||
| Advance Start | 1875 rpm | ||
| Full Advance | 30o BTDC, at 2900 rpm | ||
| Starting System | Kick starter and/or starter motor | ||
| Generator | Flywheel AC generator, 57W at 5000 rpm | ||
| Battery Capacity | 6 V, 11 Ah | ||
| Spark plug (normal) | NGK C7HS or ND U22FS | ||
| Spark plug (cold climates) | NGK C6H or ND U20FS | ||
| Spark plug (high speeds) | NGK C9H or ND U24FB | ||
| Spark Plug Gap | 0.024 – 0.028″ / 0.6 – 0.7 mm | ||
| Fuse Capacity | 10 A | ||
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hey-what kind of motor is good for rhe conversion