Topic: Increased Capacity for CB750 MOTOR

[chris]

Are you able to use pistons from another model Honda to increase the capacity without going to the expense of a big bore kit. I realise that you have to consider compression ratios etc .If this is possible what size can you go to without having to resleeve and if you have to resleeve what can anyone suggest

[kos]

If you can find them, the Yoshimura 812cc kit worked well with no liners required. the many 836cc kits also work well with no liners required. Going much larger than that... usually requires liners or you will get distortion from liner walls being too thin.

KOS

[MCRider]

Are you able to use pistons from another model Honda to increase the capacity without going to the expense of a big bore kit. I realise that you have to consider compression ratios etc .If this is possible what size can you go to without having to resleeve and if you have to resleeve what can anyone suggest

My understanding is that certain pistons will "fit" like CB350 twin. But the amount of machining you'd do to the crowns and skirts to really make them fit offset any (if any) savings from buying the pistons.

[754]

Go for it
 Std 350 twin is 812

4th over 350 twin is 836

 I think with sleeves maybe goldwing pistons.

 I have had one with 350 pistons, you at minimum must cut the skirts...if you leave the tops compression will be high..
 NOTE,
 the  350 pistoned 836 Mystery cam stock carb motor went good at topend, no joy in the middle.. I hated that thing. Hated it even more when I tore it down to find it was 836cc, not the 900cc I had been sold..
 Then I had an 836 (off the shelf kit) RC cammed  Weber carbed motor.. BIG difference.. Midrange like four should not possess.. great topend power.. great street fun..

 Do I think you will save money..?? IF you can mod your pistons yourself, then maybe..

[chris]

Thanks for the info might investigate a little further

[Big Jay]

The 350 piston also need valve pockets machined.