I've got some 750 liners for my own project. As far as I can see, the top flange on the liner will need reducing a little and then the liner will need shortening. With that done the internal chamfer needs to be added back in at the bottom and the outer diameter will need reducing to cut down the machining of the crankcase mouths.
The barrels will need to be bored and then the recess for the top flange will need opening a little. Most of the mods I have seen take the top flange as far as the stud holes.
The holes in the crankcases will need opening up a little, otherwise the liners will be very thin at the bottom. I would prefer mine to be a bit thicker.
Providing you don't go mad with compression ratio, I think that this could be a very nice mod for either a Hawk or Dream.
I am going to use CB350 pistons (64mm) with the crowns machined. I have a solid copper head gasket and it should be possible to get those made in any bore size.
Have fun!
G
big bore kit pieced together
Almost sounds like for the trouble involved in modifying various parts to make it all fit, it might be worth the extra money to have Bore-Tech do the work and be done with it.
I had them do the 358 kit for my bike (CB77), and my mechanic was very glad they did! Saved him a bunch of work and trouble, and cost-wise probably didn't make a whole lot of difference.  [/quote]Vince
You are probably quite right. That's what a sensible person would do. For me it's all about therapy and the thrill of creating something myself. I know I could spend money with the pros, and that's exactly what I would do in my professional life. In my hobby though it's all about maximising (rather than minimising) my personal input. Sadly with the amount of crazy traffic on the roads around me, I get more pleasure from an afternoon in the workshop than I do sparring with the boy racers in their Audis and BMWs. I just 'burdened' myself with a very sorry looking XL250 Motosport........ G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
I would love to just have it all done that way, but my wallet hates the idea. The whole kit costs $390 plus $179 to have the liners installed, then shipping costs of course. If I can cut a few hundred out of the equation then it's worth the trouble. I'll have to run this info by my machinist and see if it is cost prohibitive with the cb750 liners before barking up the wrong tree. All of the info everyone has provided so far is great stuff, so thanks for your input. One way or another I am going to put a big bore kit in one of the motors I just got, I just need to start saving up some pennies.
CB750 liners are fine. They need to be shortened and the barrels have to be bored to fit them and then bored again to match the pistons. The liner will need a scallop taken out of the top flange to clear one of the studs, or reduce the flange OD.
Crankcase mouth should be opened out to clear your new liners. We used to use CB350 pistons when they are all that was available and then the crowns had to be machined and that's not a lot cheaper than Boretech or Vintage Advantage pistons. There's nothing complicated about the DIY approach but the costs soon start to add up.
Thanks for the info teazer. I figure the cb350 piston machining would be a bit costly versus just buying ones that should already fit. Hopefully I can get everything in one place soon to get things started.
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