Honda CB1 Specs and Information (1989 to 1990 – aka CB400F NC27)

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Honda CB-1 NC27
1990 Honda CB1 (NC27)

Honda CB-1 Specs…..

The Honda CB-1 was a short lived but surprisingly popular (in the UK) naked, 400cc bike that was released in Japan between 1989 and 1990.
The bike was also known by it’s official Honda model code (NC27) and as the CB400F in some countries it was marketed in.

The CB1 was originally released in Japan, but was later also released in the USA and Canada.
The CB1 was a fairly ‘sporty’ feeling bike, with a small and compact design and an engine based on the fully faired CBR400 NC23 (although the engine was de-tuned for the CB-1).

Need parts for your CB1? Honda CB-1 spares on Ebay…

A little bit about the Honda CB-1…..

Basic model info…

Manufacturer: Honda
Model: CB-1
Honda model code: NC27
AKA (also known as): CB1, CB400F
CC: 399cc
Engine type: Inline twin cylinder (4 stroke)
Countries officially released in: Japan, United States and Canada (grey import in the UK)
Years in production: 1989 to 1990
Style of bike: Naked bike
Insurance: Group 8 (of 17) – Get a cheap insurance quote from Carole Nash

Models and years (in the UK)

Note: The CB-1 was a ‘grey import’ in the UK, which means it was never officially released by Honda in this country.
The bike was available here, but not new from Honda (models available would have been registered in other countries where it was officially released and imported 2nd hand to the UK by importers, dealers and private individuals).

CB-1 (1989 to 1990)…..
Description: Unfaired 399cc bike with 17 inch front and rear wheels, Showa 41mm front forks, single front disc brake and a engine based on a de-tuned NC23 engine.
Available colours: Red, yellow and blue
CB-1 front view
Honda CB1 front view. Fitted with aftermarket headlights.

Engine and gearbox specs…..

Displacement: 399cc (24.3 cubic inches)
Engine type: Inline 4 cylinder
Engine weight: 57kg (126lbs)
Stroke: 4 stroke
Boreร—Stroke: 55.0 x 42.0mm (2.17 x 1.65 inch)
No. of cylinders: 4 (inline)
Firing order: 1 – 2 – 4 – 3
Cam shaft configuration: DOHC (double overhead cam – gear driven)
Compression ratio: 11.5:1
Cylinder compression pressure: 12.5 to 13 bar (182 to 188 psi)
Valves: 16 valve (4 per cylinder)
Spark plug: NGK CR8EH-9 (x4)

Note: Honda recommend using the NGK CR9EH-9 spark plug instead of the standard CR8EH-9 for extended, high speed riding…….and no, on the road you won’t be fast enough for this! ๐Ÿ˜€

Spark plug gap: 0.8 to 0.9mm
Engine oil system: Forced pressure from a wet sump in bottom of the engine
Oil pump: Trochoid type oil pump

Note: A Trochoid oil pump has an inner and outer rotor with different numbers of teeth (e.g. the outer rotor can have 5 teeth and the inner can have 4 teeth). The difference in teeth creates uneven spaces inside the pump which causes the oil to move to fill the gaps as the inner rotor rotates (example below, not from a Honda engine).
Trochoid pump
Unfortunately, these pumps do suffer from pitting if the incorrect oil has been used in the engine (e.g. car oil).

Engine oil: 10w40 API SG or higher

Note: You can use any grade oil in the CB1 engine (mineral, semi synthetic or full synthetic). Although fully synthetic is the best and will offer the best protection for your engine, we normally recommend a semi synth as it’s a good balance between engine protection and price. More info…

Engine oil capacity (with filter change): 3.1 litres
Engine oil capacity (without filter change): 2.9 litres
After engine rebuild/disassembly: 3.5 litres
Engine oil drain bolt location: Bottom/right of the engine oil sump (right as your sitting on the bike)
Oil filter type: Canister type
Oil filter: Hiflo HF303 / Filtrex OIF006
Oil filter torque: 10nm
Oil pressure: 4.9 bar / 71psi (at oil pressure switch)
Clutch: Wet (oil immersed) multiplate clutch
Clutch operation: Mechanical / cable
Clutch lever free play: 10 to 20mm
Gearbox: 6 Speed manual
Gearbox configuration: 1st Gear down, 2nd to 6th gears up, neutral between 1st and 2nd gears (1 – N – 2 – 3 – 4 – 5 – 6)
Gear change operation: Pedal operated by left foot
BHP (claimed!): 55 bhp (@ 10,000 rpm)
Torque (claimed!): 29 ft/lb (@ 9,500 rpm)
Top speed (claimed): 118mph

Note: BHP, torque and top speed figures are ‘claimed!’ based on Honda marketing stuff (it’s not uncommon for manufacturers to inflate these figures as it helps sell more bikes!).

Piston ring to cylinder bore clearance: 0.10mm (max service limit)
Valve clearance (inlet): 0.12 – 0.18mm (when cold)
Valve clearance (exhaust): 0.17 – 0.23mm (when cold)
Idle speed: 1,300rpm (1,400rpm for California models – +/- 100)
CB-1 engine - right
CB-1 engine - left
Honda CB1 399cc, inline 4 cylinder engine

Cooling system stuff…..

Cooling system: Liquid cooled
Cooling system capacity (complete system – radiator, engine and reservoir): 1.8 litres
Cooling system capacity (engine and radiator): 1.5 litres
Cooling system capacity (reservoir only): 300ml
Water pump location: Bottom/left of engine (just infront of the front sprocket cover)
Coolant reservoir location: Front/right, underneath the seat (between the back of the tank and the battery)
Water pump drain bolt location: Bottom of the water pump (lowest short bolt on the pump)
Thermostat begins to open at: 80 to 84 degrees C
Thermostat fully open at: 95 degrees C
Fan motor switch turns on at: 98 to 102 degrees C
Fan motor switch turns off at: 93 to 97 degrees C
CB1 NC27 side view
Left side view of a 1990 Honda CB1

Final drive stuff…..

Final drive: Chain
Front sprocket: 15 teeth
Front sprocket nut tightening torque: 55mm
Rear sprocket: 37 teeth
Rear sprocket nut tightening torque: 65mm
Chain pitch/length: 525 pitch / 104 links
Chain free play: 15 to 25mm
CB-1 HF303 oil filter
Honda CB1 (NC27) canister type oil filter (Hiflo HF303)

Carb, fuel and oil stuff…..

Fuel system: Carburetor
MPG (average): 44 miles per gallon (very approx)

There are variations in MPG between users, mainly due to different riding styles and areas (e.g. city riding vs open road)

Fuel tank capacity: 11.5 litres
Fuel tank reserve capacity: 3.5 litres
Fuel type: Unleaded petrol (91 octane grade – aka standard petrol from your local garage)
Carb make: Keihin CV32 (4x)
Carb type: VG06B (VG06C in California)
Pilot screw opening: 1 turn
Throttle grip free play: 2 to 6mm
Engine oil: 10w40 API SG or higher

Note: You can use any grade oil in the CB1 engine (mineral, semi synthetic or full synthetic). Although fully synthetic is the best and will offer the best protection for your engine, we normally recommend a semi synth as it’s a good balance between engine protection and price. More info…

Engine oil capacity (with filter change): 3.1 litres
Engine oil capacity (without filter change): 2.9 litres
After engine rebuild/disassembly: 3.5 litres
Engine oil drain bolt location: Bottom/right of the engine oil sump (right as your sitting on the bike)
Engine oil drain bolt tightening torque: 35nm
Oil filter type: Canister type
Oil filter: Hiflo HF303 / Filtrex OIF006
Oil filter torque: 10nm
Oil pressure: 4.9 bar / 71psi (at oil pressure switch)
CB-1 Cockpit layout
CB1 clocks
Layout of the clocks and handlebars on a CB-1 (NC27)

Electric stuff…..

Ignition type: Electronic CDI
Starter: Electric start
Electrical system voltage: 12 volts
Battery voltage (fully charged): 12.8 volts
Battery amps per hour: 8 a/h
Battery will need charging if below: 12.5 volts
Battery charging current (normal): 0.9 amps on a 5 to 10 hour charge
Regulated voltage: 14 to 16 volts (@ 5000 rpm)
Spark plug: NGK CR8EH-9 (x4)

Note: Honda recommend using the NGK CR9EH-9 spark plug instead of the standard CR8EH-9 for extended, high speed riding…….and no, on the road you won’t be fast enough for this! ๐Ÿ˜€

Spark plug gap: 0.8 to 0.9mm
Spark plug tightening torque: 11nm
Spark plug ignition: 2 x coil
Battery: CTX9-BS / YTX9-BS / CBTX9-BS

Notes:

  • The YTX9-BS battery is a 12 volt, 8 amp/hour battery and is length: 151mm width: 87mm height: 106mm in size (more info…).
  • The 1st letter(s) of the battery reference code are a manufacturers reference mark and may vary between different battery makes (different battery manufacturers use different 1st letters), so CTX9-BS, YTX9-BS and CBTX9-BS are all the same battery just from different manufacturers (more info…).
  • Also…… Avoid buying the cheapest of the cheap type batteries online as they have a horrendous failure rate (and they can be a bug!er to post back when it fails.
CB-1 battery
Honda CB-1 battery (YTX9-BS)

Shocks, brakes and wheel specs…..

Front wheel type: 3 spoke cast wheel
Front tyre size: 110/70-17
Front tyre pressure: 33psi (2.3 bar)
Front wheel spindle torque: 60nm
Front wheel spindle clamp bolt torque: 22nm
Rear wheel type: 3 spoke cast wheel
Rear tyre size: 140/70-17
Rear tyre pressure: 36psi (2.5 bar)
Rear wheel spindle torque: 90nm
Front brake: Single hydraulic disc brake with 2 piston caliper
Front brake disc: 310mm single disc. Part no: EBC MD1038RS (1x)
Front brake pad: EBC FA142 (1x)
Rear brake: Single hydraulic disc brake with 1 piston caliper
Rear brake pad: EBC FA140 (1x)
Rear brake disc: Single 240mm disc. Part no: EBC MD1020 (1x)
Brake fluid (front and rear): DOT 4 brake fluid
Front suspension: Telescopic forks (Showa)
Front fork stanchion diameter: 41mm
Recommended fork oil: 10w (medium weight) fork oil
Fork oil volume: 510 ml (per fork)
Front wheel travel (up/down):
Rear suspension: Single rear monoshock
Rear shock type: Gas filled (nitrogen) with preload adjustment
Rear shock top mounting bolt torque: 45nm
Rear shock bottom mounting bolt torque: 45nm
Rear shock lower joint bolt torque: 68nm
Rear wheel travel (up/down): 110mm
CB-1 front wheel
110/70-17 Front wheel with single front disc on a Honda CB-1

Weights, measures ‘n stuff…..

Overall length: 2,035mm
Overall width: 705mm
Overall height: 1,025mm
Wheelbase: 1,370mm
Seat height: 775mm
Footpeg height: 335mm
Ground clearance: 130mm
Dry weight (no oils, fluids etc): 170kg
Kerb weight (with oil, coolant etc – approx): 183kg
Max weight capacity: 157kg
CB1 top
Top view of a 1990 Honda CB400F NC27

Useful torque settings…..

General nuts, bolts, screws and fastners…
5mm bolt and nut: 5nm
6mm bolt and nut: 10nm
8mm bolt and nut: 22nm
10mm bolt and nut: 35nm
12mm bolt and nut: 55nm
5mm screw: 4nm
6mm screw: 9nm
6mm flange bolt (with 8mm head): 9nm
6mm flange bolt (with 8mm head): 12nm
8mm flange bolt and nut: 27nm
10 mm flange bolt and nut: 40nm
Specific/important nuts, bolts and fastners…
Oil pressure switch: 12nm
Oil drain bolt: 35nm
Oil filter: 10nm
Spark plugs: 11nm
Front sprocket nut: 55mm
Rear sprocket nuts: 65mm
Front wheel spindle torque: 60nm
Front wheel spindle clamp bolt torque: 22nm
Rear wheel spindle torque: 90nm
Front brake caliper bolt: 30nm
Rear brake caliper bolt: 30nm
Cylinder head cover bolt: 10nm
Camshaft holder bolt: 12nm
Alternator flywheel bolt: 85nm
Engine mount nut (front): 40nm
Engine mount nut (rear/upper): 50nm
Engine mount nut (rear/lower): 50nm
Front brake disc bolt: 30nm
Front caliper bracket bolt: 27nm
Front caliper bolt: 23nm
Rear brake disc bolt: 40nm
Rear caliper bolt: 23nm
Rear shock top mounting bolt: 45nm
Rear shock bottom mounting bolt: 45nm
Rear shock lower joint bolt: 68nm
Front NC27
Front view of a Honda CB1 (NC27) with aftermarket ‘streetfighter’ headlights

Service stuff…..

Servicing your bike? You’ll need tools and CB-1 parts…
Engine oil
Engine oil change frequency: Every 12,800km (approx 7,900 miles) or 12 months
Engine oil: 10w40 API SG or higher

Note: You can use any grade oil in the CB-1 engine (mineral, semi synthetic or full synthetic). Although fully synthetic is the best and will offer the best protection for your engine, we normally recommend a semi synth as it’s a good balance between engine protection and price. More info…

Engine oil capacity: 3.1 litres
Engine oil drain bolt location: Bottom/underneath of the engine
Oil filter: Hiflo HF303 / Filtrex OIF006
Oil filter torque: 10nm
Chain drive
Final drive chain check frequency: Now repeat after me… ‘I MUST LUBE MY CHAIN LITTLE AND OFTEN!!’
At least once a week…
Chain and sprocket size: 104 link / 525 pitch Chain, 15 tooth front and 37 tooth rear sprocket
Hydraulic brake system (front and rear)
Brake fluid check frequency: Check every 12 months or 6,400km (approx 3,900 miles)
Brake fluid change frequency: Change every 24 months or 19,200km (approx 11,900 miles)
Brake fluid: DOT 4 brake fluid
Fork oil
Front fork oil check frequency: Check every 12,000km (approx 7,456 miles) or 12 months
Recommended fork oil: 10w (medium weight) fork oil
Fork oil volume: 510ml (per fork)
Cooling system
Coolant check frequency: Check every 12,800km (approx 7,900 miles) or 12 months
Change every: 38,400 km (approx 23900 miles) or 24 months
Cooling system: Liquid cooled
Cooling system capacity: 1.8 litres
CB-1 back view
Back view of a 1990 CB-1 NC27

Frame number location…..

The frame number is stamped onto the right side of the headstock (the front part of the frame just below the handle bars).
There is also a information plate on the right of the bike, on the frame just behind the headstock and just below the tank.

Engine number location…..

On the right side of the engine crankcase, just behind where the clutch cable joins the clutch arm (the engine number usually starts ‘NC23….’.

Useless stuff…..

Although the CB-1 wasn’t a popular bike for Honda, it has proved popular in other countries where it was officially released and in countries, like the UK, where it was imported as a ‘grey import’.
The CB1 was released at a time when the market was changing and people weren’t looking for sporty. unfaired bikes and were looking for sportier, fully faired bikes (e.g. CBR400, CBR600 etc). This meant the CB1 was a hard sell for Honda. Officially, the bike was sold between 1989 and 1990, but it was available new up until 1992 in some countries at a discounted price to clear stock (the bike was known as the CB400F in the US).
The CB1 has proved popular with newer, 1st ‘big bike’ riders, couriers and, due to it’s smallish size and low seat height, shorter riders.
The sporty ride of the bike is achieved, it part, by the frame design and clip on handle bars (as opposed to more traditional handle bars used on many ‘naked’ bikes) and the use of an engine based on the CBR400RR NC23 engine. The CBR400 engine was de-tuned for the CB-1, with changes to the port lengths as well as smaller valves and lower compression ratio. Other changes were in the primary and secondary gear ratios which meant the 1st gear speed was reduced from 60 mph (in the CBR400) down to around 30 mph (although this meant the CB1 was quicker off the mark then the CBR400!).
Although never official in the UK, there have been many CB1’s with upgrades and extras over the years. Many have been modified with a CBR400 forks and front brake system, which converts the single front disc brake to a twin front disc brake, as well as braided brake hoses, performance and home made exhaust systems and other parts.

Buying advice…..

Firstly, if your thinking of buying one always HPI check it (there’s still loads about so no point risking getting stuck with a lemon!).
These are good, solid bikes and are ideal for 1st time ‘big bike’ riders as well as shorter (lady) riders. Mileage isn’t really anything to worry about (within reason!), but obviously a bike that’s had frequent oil changes is likely to be better.
As the bike was a naked/unfaired bike there’s wasn’t alot of fairing to damage and indicators, headlights etc could be easily replaced, if damaged, with aftermarket parts.

Obviously, the youngest of these bikes will be 27 years old now so if your buying you’ll need to check any metal parts, especially exhausts, forks and similar (also check the availability of parts as grey import bike aren’t always the easiest to get parts for!).
Although the CB-1 is fairly reliable (gear driven cams etc), there are a fair few ex courier and winter bike hacks around, which aren’t always a bad buy, but will invariably always need something doing to them.
Common part’s like reg/recs, brake pads, clutches, chain and sprocket kits, caliper pistons where shared between a few Honda models to these parts aren’t difficult or expensive to source.

Happy biking ๐Ÿ™‚

Sources / Thanks to / Useful CB1 sites:

CB-1 article on Wikipedia
www.hondacb1.org Loads of helpful owners and info
Honda CB1 service manual (pdf)

If you’ve got any questions, comments or suggestions please feel free to leave them below ๐Ÿ™‚

Disclaimer: The information on this page is correct to the best of our knowledge. But the info should NOT be taken as 100% accurate as we can, occasionally make mistakes!

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