First, this is just a fantasy. Now, let`s consider the specifications and details of the completed vehicle were aiming for, how to combine parts, and what needs to be newly created. As part of the groundwork, I am studying the basic information of not only the original CB1100R but also the CB1100(SC65) & CB1300SF(SC54). This includes brochures, maintenance documents (shop manuals and parts lists), & magazines. In particular, Im expanding my imagination by closely observing the actual CB1100 & CB1300SF models.

The original CB1100R came in three models: RB (1981), RC (1982), and RD (1983). The initial model had the non-cowl RB-I and the half-cowl RB-II, both featuring a single-seat setup. Starting with the RC, it adopted a full cowl design & incorporated a detachable seat cowl to accommodate two passengers. The final RD model saw significant updates including a pearl white paint and candy red accents, a shortened upper cowl to comply with racing regulations (the vertical line at the front end of the cowl must not extend beyond the front axle shaft), & a box-shaped swingarm. As such, I have chosen the CB1100RD as the homage model. The reason is that while the initial R series models were clearly homologation models, the final RD model was not only refined but also had an appealing elegance.

For the base frame of the RCB, I have selected the 2018 model year CB1100 (SC65), & for the engine, the 2012 model year CB1300SB (SC54). Using a recent model frame (CB1100 SC65) would complicate the custom vehicle inspection process due to stringent emission regulations, so I believe this combination is suitable. Honestly, if the budget allowed, I would have preferred to use the latest CB1300SF engine & other parts, but I had to make do. Finding a black-painted engine, which was a must-have, was quite a challenge even in the used market. Here are the specs for the three bikes and the anticipated specs for the RCB.

CB1100RB-Ⅱ(SC05)
NameCB1100R(D)CB1300SF(Donor)CB1100(Donor)RCB
ModelSC08EBL-SC54EBL-SC65SC65改
Year of manufacture1983201220182024？
Expectation
Overall length(mm)2,1152,2202,2052,210
Overall width(mm)770790835780
Overall height(mm)1,3401,1201,1301,280
Wheelbase(mm)1,4901,5151,4901,500
Ground clearance(mm)170135125125
Caster angle/Trail length(mm)28/11825/9927/11426.5/97
Seat heigt(mm)795790765780
Curb weight(kg)233264243260
Riding capacity(people)1(2)221(2)
Tank capacity(ℓ)26211820
Minimun turning radius(m)2.7
Type of EngineSC05ESC54ESC65ESC54E
Cylinder arrangement4 cylinders in-line, Air cooled4 cylinders in-line, Liquid cooled4 cylinders in-line, Air cooled4 cylinders in-line, Liquid cooled
Valve trainChain driven DOHC 4valvesChain driven DOHC 4valvesChain driven DOHC 4valvesChain driven DOHC 4valves
Displacement(cm3)1,062cc1,2841,140.51,284
Bore and Stroke(mm)70.0×69.078×67.273.5×67.278×67.2
Compression ratio10.0：19.6：19.5：19.6：1
Maximum Power(ｋW[PS]/rpm)120ps/9,000rpm101ps/7,000rpm88ps/7,500101+ ps/7,000rpm
Maximun Torque(N-m[kg･m/rpm]10.0kg-m/7,500rpm11.6kg-m/5,500rpm9.4/kg-m/5,000rpm11.6kg-m/5,500rpm
TransmissionConstant mesh, 5-speedsConstant mesh, 5-speedsConstant mesh, 5-speedsConstant mesh, 5-speeds
Fuel Delivery System TypeCarburetor VB53C Ø33(Keihin)PGM-FIPGM-FIPGM-FI
Starting systemElectric stater motorElectric stater motorElectric stater motorElectric stater motor
BrakesFrontØ296 Hydraulic doble discØ310 Hydraulic doble discØ296 Hydraulic doble discØ310 Hydraulic doble disc
RearØ296 Hydraulic doble discØ256 Hydraulic doble discØ256 Hydraulic doble discØ256 Hydraulic doble disc
TiresFront3.50-19120/70ZR17110/80R18120/70ZR17
Rear130/90-18180/55ZR17140/70R18180/55ZR17

So, organizing my fantasies and compiling the challenges and concepts,

To summarize my thoughts, challenges, and concepts:

The suspension components from the CB1300SF will be transplanted to both the front and rear. By installing the shorter front forks (with 17inch wheels) of the CB1300SF onto the CB1100 frame, the caster angle of the CB1100 will become steeper, and the trail will decrease. This will result in a more forward-leaning frame dimension, potentially giving the bike a more aggressive riding character. I decided that the final tuning will be done by adjusting the protrusion amount of the front forks. The rear swing-arm will be 10mm longer compared to the CB1100. How will this affect the ride? Using a CB1100RS (caster 26mm/trail 99mm/17inch tires) as the donor bike might be a shortcut, but…

The first step: painting the frame red (July 2022).

Original
Applying a White primer
Finished painting!

August 2022. Removed the head cover and oil pan, and mounted the engine to the frame…. To be continued in Project RCB Part 2.