Guess Why?

Lets play little guess game with subject of Honda CB815 cafe-racer. Here is couple of photos to start.

Q: Why I draw some strange figures, mostly circles on 1mm graph paper?

A: I need to make electronic drawing of some part.

Sure, there is no need to guess why I make that 3D drawing. I need some part to be CNC machined from aluminum.

Q: What is this part for?

A: This part is a spacer that is to be put between clutch cover and engine case. That’s why part’s  outer shape meticulously repeats the contour of clutch cover.

Q: But really, why clutch cover needs be placed further than usually  from engine case?

A: Custom made clutch basket of new reinforced clutch protruding too far from engine case.

Q: Why do my Honda CB815 cafe-racer needs reinforced clutch?

This question I leave without answer for some time, but here is a small hint: the matter of this upgrade is related to what you may see on photo below…

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  1. Piotr

    What carb jet sizes did you use in your seven fifty?

    1. gazzz (Post author)

      Hi Piotr,

      Sorry for late answer.

      Th main jets currently are 130. I also used slightly larger pilot jets, but I don’t remember of what exactly size.

      Kind regards,

  2. Piotr Milcarz

    Thanks for your help Nazar. I will try to find somewhere which size od pilot jets should I use.

  3. Robert

    Does the sven fifty exhaust header fits the CBX cilinder head? Thx!! Robert

    1. gazzz (Post author)

      Hi Robert,

      Yes, headers are compatible, but there is difference. Both OEM header are of “pipe in pipe” type, see on this photo what i mean:

      Seven Fifty inner pipes are of smaller diameter than those of CBX.

      Yet one insignificant difference: exhaust studs of CBX750 is 8mm to 6mm while Seven Fifty studs are 8mm to 7mm.

  4. Travis

    Awesome build!

    What were the final dyno numbers on HP and TQ?


    1. gazzz (Post author)

      Hi Travis,

      We decided to keep this information unpublished until we’ll get a chance to participate in drag racing on some international cafe-racer event this year.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

      1. Travis

        Please keep me posted if you do that! What do you think it would run in the 1/4 mile? I have a 1992 Honda Nighthawk 750, my best pass was 12.73


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