
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 Amazon…
A little bit about the Honda CB-1…..
Basic model info… |
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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) – Need bike insurance? Get a quote at Confused.com |
Models and years (in the UK) |
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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 |

Honda CB1 front view. Fitted with aftermarket headlights.
Engine and gearbox specs….. |
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Displacement: | 399cc (24.3 cubic inches) |
Engine type: | Inline 4 cylinder |
Engine weight: | 57kg (126lbs) |
Stroke: | 4 stroke |
Bore×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) |
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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 |
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Engine oil: | 10w40 API SG or higher
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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 |
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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) |


Honda CB1 399cc, inline 4 cylinder engine
Cooling system stuff….. |
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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 |

Left side view of a 1990 Honda CB1
Final drive stuff….. |
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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 |

Honda CB1 (NC27) canister type oil filter (Hiflo HF303)
Carb, fuel and oil stuff….. |
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Fuel system: | Carburetor |
MPG (average): | 44 miles per gallon (very approx)
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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
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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) |


Layout of the clocks and handlebars on a CB-1 (NC27)
Electric stuff….. |
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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) |
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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
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Honda CB-1 battery (YTX9-BS)
Shocks, brakes and wheel specs….. |
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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 |

110/70-17 Front wheel with single front disc on a Honda CB-1
Weights, measures ‘n stuff….. |
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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 |

Top view of a 1990 Honda CB400F NC27
Useful torque settings….. |
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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 view of a Honda CB1 (NC27) with aftermarket ‘streetfighter’ headlights
Service stuff….. |
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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
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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 |

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 🙂
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 🙂
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!
I got a 1990 with 13k miles – love the bike. Great info! What were your reference sources for the specs?
Reference sources are…..
-Me (I’ve owned a few of these over the years)
-Collection of old service and spec books
-And there is a service manual available online for this bike (there’s a link to at at the bottom of the above article) 🙂
I was 16 when I saw this at the dealership. I still want it and have been getting kinda serious about. Being 5’10” I wonder if it would be a good fit. Comfortable enough for longer rides. Any opinion?
I have one. Im 5’11”. Im ok on the bike, but its more a fun bike than nice touring bike. My previous bike was a Vstrom 650 2014 that was very good bike for long traveling. Ilove my CB1 for short run…1h30 max. I can use all the power at full throtle and the feedback of the screaming 400cc 4 cylinder is like my older GSX750r when I was young! But not dangerous or fear to lost licences.
I keep my CB1 for what it is….a litle very funny bike that can surprise many biker. I owned many sport and touring bike…but I can sold my CB1. Its like a toy, easy to ride, and there is nothing that sreaming like a 4 banger carburated a 13 500 tr/min lol.
I am 5′ 10′ and have owned these bikes for years . Never a problem in fact , it’s an advantage -You’re tucked in more like being part of the bike and the with smaller height it’s quite wonderful with town use and being able to put your feet flat to the ground. The handling on these bikes is second to none , they are so well balanced- Even these days with modern bikes I have never felt the ability of the bike to be out classed by new machinery . Long rides , well this summer with almost every day being a biking day my long rides they were very long indeed . How about an average of 200 miles every day and never ever feeling the effects of any type of back ache or wrist ache … I have owned 100 plus motorcles since 1969 and will say in all honesty that there have only been very few bikes that have been able to outclass them in any way . Yep they aren’t the fastest bike out there but in all reality you don’t need that massive top end . I’ve owned bikes that can do 170 mph plus and always got frustrated that I couldn’t ever use that power ( only when I lived in Germany was I able to open the bikes up) but really after you do that a few times , that novelty wares off )…No the real rush is between 50 and 80 which is just perfect for these UK roads …One thing be wary of getting one of the old dispatch riders bikes , they were very popular in the early 90’s with the London boys who would thrash them around the city …Top tip . When on tick over that engine should sound sweet , because they don’t have a cam chain ( Direct drive Cam GearDrive ) so no rattles . Try if you can to get one of the MK1’s , they were built for the JDM and are of much higher quality re- alloy’s with a full factory made stainless steel system . The DVLA have confirmed to me that there are only 57 in total in the UK . Many of these being the USA/ Canadian model that were produced in 1991 . All bikes that came into the UK get reg as on a 1989 plate for convienience . They had a production run of only 22.000 and that was split into three batches . 10.000 -1989- 8.000 -1990 and the final year of production 1991 with only 4.000 made and these were for the USA/ Canada. These are the MK2 versions with a steel exhaust system , steel passenger foot rails. Black headlight surround , reflector strips on the forks and their clocks will be in MPH. As of summer 2022 there are only 7 MK1’s reg for the UK roads of which I own 3. They are rare and going up in value quickly , you will be hard pressed to find the MK1 . Back in Novemeber 2021 Classic Motorcycle Magazine did a main page review of the bike, with cover photo and up to that point you could get one in superb condition( original ) not restored for £1.500 because I did and was pleasantly surprised to find a few months later that the value of the bike had gone up by more than 100%. They are now worth on the classic scene a min of £3000 plus . They have to be original nothing changed ,no resto 100% factory spec . I have been lucky enough to find another one for my collection only last week – I now own 3 of the current 7MK1’s on UK roads so I can sell for what I like . There is no actual market value and they will only go up in value . I could sell my collection of all 3 for at least £9000 min . So good luck in finding one they are getting rarer and rarer as each year passes . Remember you will have to be able to fork out £3000 for a good one or you could get a MK 2 for less . The MK 2 just doesn’t cut itin the looks dept , in fact it looks like a different bike altogether . All the best Simon .
cb1 400cc 1990 can you tell me how to check engine oil level exactly dip stick screwed in or screwed out
best regard
Screwed out, 100%
I got problem with my valves,I just replaced new engine head .but how to set the timing gears
I own two CB1’s both manufactured in 1989 . these are the MK 1 models which were also produced for 1990. The MK2 series was produced for the USA / Canadian market . Subtle differences for the two bikes . The alloy billet for the MK1 , pillion footrests not steel like the MK 2 . Stainless steel exhaust system for the MK1 was replaced by a mild steel all black system, black plastic headlight , reflectors on the front forks MK2 …Total production 22.000 world wide . 1989 -10.000-1990-8.000 – (MK2 -1991 -4.000- for the USA/ Canadian market) I have been in contact with Honda Japan Hammatsu via their messenger service and talked with a very helpful Japanese lady who spoke English . She confirmed the details and she sent me ( In Japanese ) the total production figures for every Honda CB1 -400 made in Japan and I have had the info translated into English . Bikes with the KM clocks were made for JDM and some other Pacific rim countries. ( JDM =Japanese Domestic Market). Some found their way to Australia and a few went to Hong Kong the Hong Kong bikes will have mph clocks like one of mine . I have two bikes from the same monthly production run in 1989. Rumour has it that in 1989 Honda tested the waters in Japan with 500 CB1’s with the CBRR 400 engine prior to changes they made with the gearing …For reference the 3rd gear on the CB1 is the Ist gear on the CBRR 400 . They are very sought after , I have contacted the DVLA and as of summer 2022 there are only 57 CB1’s reg for the road – 7 are the MK1 1989 JDM models and the remainder are the MK2 version …That doesn’t mean there aren’t more, possibly on sorn waiting for rebuilds . resto’s or just sitting around in garages… Hope people find this useful ?
Max power of 57bhp reached at 10.000 rpm – warning don’t bury that needle into the red for any length of time , it could overload the cams and you might get into a situation with valve bounce , meaning it will be reving so high that they hover and can’t actually close because the engine is spining so quickly …These engines were race derivedd so are needing to be used , they perform better when above 6.000 rpm and can easily reach 80mph pretty damn quick . For reference the 3rd gear if used properly can do 0-to 75 in one gear , That was the 400 R’s first gear . all Honda did was a re- gear configeration for road use , so you have a short shift to get to 30 pus in 1st- 2nd all the way up to 50 , then if used like a race bike full on until 75-80 -I’ve done it many times , then with the 4th gear it’s just extra until you reach 5th around that mark you will be hitting max power of 10.000 rpm . 6th gear will be stable at top speed of a max around 118-120 Wrongly stated in the blog as being a different engine as the CB400R , the engines are exactly the same and will have a stamp on the right side of the engine , where the clutch cable sits , pull back the cable and you find NC23E.( all CB1 400 ‘s will have a classifiaction of NC27 that is for the frame and running gear, handle bars etc. The NC23 E denotes the same engine as the CB400R the difference between the engines on both bikes is the gearing , with the R having that very tall 1st gear . Made for racing in Japan’s race series at the time . If you need any more information please feel free to contact me ok .I am in contact with Honda’s headquarters in Hamamastsu in Japan . I have in my possesion the listings. codes, production runs , the amount of bikes made , details of years of production and the list gives me every single Japanese bike manufactured from 1966 until the present day . This for the JDM only ( Japanese Domestic Market) doesn’t include bikes made under the Honda name built in other coutnries .Ths list doesn’t even include the CB1-MK2 variants because all Honda did was ship over the engines from Japan and the rest of the M2 was built in Honda’s USA plant …It was the American arm of the Honda company that decided on not supplying the MK2 with steel exhausts , steel footrest hangers and other bits . mainly to do with cost , they were testing the waters with the US model to see if it would sell and it didn’t do well ( there were only 4000 models built in the US . One reason was the bike cost more to manufacture than the then current ‘Jelly Mould CB600 F’ sales seemed to go to the 600 and not to the 400 as was expected . The world wasn’t ready for a naked ‘cafe racer styled bike at that point , all people wanted was the race look which was all popular in the late 80’s early 90’s …Many despatch riders bought these bike that were either shipped over from Japan or the US by container , I know because I was one of the importers ..haha.