Honda CB815 Eight Fifteen summary.

Frame: modified Honda CB750 RC42 Seven Fifty

Engine: high performance custom mix of CB750 RC42 and CBX750 RC17 with 815ccm barrels.  Ported and polished cylinder head channels.  Engine also was glass blasted, painted and all its covers polished. CBX750 six speed gearbox and clutch.

Clutch drive: hydraulic, Kawasaki  Vulcan 1500 master cylinder with Kawasaki Zephyr lever, CBX750 slave cylinder. Hel braided hose.

Intake: custom made stainless steel pipes, Kijima pod filters. Rejetted CBX750 carburettors.

Exhaust: 4in4, custom made ceramic coated downpipes, old school MC offset flange mufflers.

Electrical System: CBX750 modified wiring, CBX750 ignition unit, CB750 Seven Fifty  relay rectifier and starter relay,  Aliant 7Ah LIFePO4 battery (hidden under swingarm), custom made components’ mounts and housings.

Front suspension: original CB750 Seven Fifty 41mm front fork with preload adjusters, original lower triple tree and Nighthawk 750 upper triple tree. Kijima fork gaiters.

Rear suspension: Kayaba fully adjustable rear shocks with custom made adjusters, Kawasaki Zephyr 750 aluminum rear swingarm.

Rear wheel:  Honda Translap 650 rear hub, Warp9 17″ 4.25″ wide rim, custom made spokes. 160/70-17 Bridgestone G528 tire.

Front wheel:  custom front hub, Warp9 17″ 2.5″ wide rim, custom made spokes. 120/80-17 Dunlop K375 tire.

Front brakes:  two 300mm discs with Nissin dual piston calipers. Kawasaki  Vulcan 1500 master cylinder with Kawasaki Zephyr lever.  Hel braided brake hoses.

Rear brakes:  240mm brake disc with Tokiko single piston caliper. Hel braided brake hose.

Fuel tank: Honda CX500 tank modified for Moto Guzzi  fuel petcock , cap with modified lock. Custom paint.

Seat: custom made, aluminum base.

Fenders: custom made steel front fender, custom made aluminum hugger. Custom paint.

Lighting:  8” British style headlight, custom made LED turn lights, custom made LED tail light in aluminium housing.

Gauges: T&T “all-in-one” dashboard, custom made side stand indicator, T&T oil temperature gauge, T&T analogue clocks.

Handlebar: Kawasaki ZX6R clip-ons. CBX750 handlebar switches.

Misc,  custom made:  stainless steel passenger and rider footpegs, aluminium rider footpegs’ platforms, aluminium license plate holder, aluminium chain guard.

Weight, without fuel and engine oil: 195kg, for 20kg less then dry weight of original CB750 Seven Fifty .


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  1. rick bradner

    so much to like here to comment on everything, but I love that the seat has shape and not just a skateboard with foam. I see the tank is from a CX500 but with the paint it reminds me of a Bultaco Metralla. Sweet bike!

  2. asakura akio

    hi, how much power does it make ?

    1. gazzz (Post author)

      Hi Asakura,

      We decided to keep this information unpublished until we’ll get a chance to participate in drag racing on some international cafe-racer event this year.

      Kine regards,

  3. Steven

    Very nice.

    Can you give a walk through of what you did to the tank to make it fit? Ty

    1. gazzz (Post author)
  4. John

    Hi lovely bike I’m just about to start a cafe racer out of my CB750 with my 13 year old son we have been looking round for ideas and have had some different ideas but both looked at your exhaust and both loved it. I assume you made it did you use any drawings or sizes that you could pass on or could you make another that you would sell ? Once again love this bike many thanks John and Robert.

    1. gazzz (Post author)

      Hi John,

      Initially it was a 4in1 exhaust, made in Japan. I found it on the local market, cut, modified downpipes and got them ceramic coated. Here is the story:

      So, alas, I have no drawings for it.

      Wishing the great kick-start of the very best New Year! May your project bring your and your son a lot of joy!

      Kind regards,

  5. Jason F Birch

    Wow! I found this trying to find the differences between a cb750 nighthawk and a cbx750 engine as far as the significant power increase/decrease. The nighthawk engine is the same as the cb seven fifty as far as I can tell. I’m assuming it’s heads and cam since bore and stroke are the same. Are they a direct swap? I’m looking to put a nighthawk motor in a cross kart ish build with a turbo and fuel injection. Just want to get the na power up first.


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