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Discussion Starter · #1 ·
Anyone happen to know what the largest oversize you can safely bore out a set of CB450 jugs to? The stock bore is 70mm and I just measured the the cylinder wall to be around 3mm.
Googling around the V8 crowd seems to think 3mm is the minimum cylinder wall thickness you would want to get away with but their engines run hotter and have A more aggressive stroke.
Any insight appreciated!
-G
 

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12'th over (3mm) is commonly considered to be the max on stock sleeves- at least that's as big as you'll be able to find parts for.
 

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Discussion Starter · #3 ·
Wow, I guess motorcycle sleeves can run thinner than the big American V8s out there.
I actually found some 74mm pistons, I'll give them a go and see what happens.
-G
 

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Suzuki GS500 is 74mm, I've put a set into XS400 DOHC and, CB360. (makes a 426 I think, maybe 436?) CB360 is 392cc with 70mm pistons
Yamaha XS650 is 75mm. (or bigger, depends what your trying to do, I've got an 86mm one :lol: )
I forget pin size and crown height offhand though. (17~20mm)
I'll measure them when I get time.
You need minimum 3mm wall thickness, slightly more at top flange.
Honda's have advantage of fully supported base gaskets so they don't leak like XS Yamaha does
PJ
 

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crazypj said:
Suzuki GS500 is 74mm, I've put a set into XS400 DOHC and, CB360. (makes a 426 I think, maybe 436?) CB360 is 392cc with 70mm pistons
Yamaha XS650 is 75mm. (or bigger, depends what your trying to do, I've got an 86mm one :lol: )
I forget pin size and crown height offhand though. (17~20mm)
I'll measure them when I get time.
You need minimum 3mm wall thickness, slightly more at top flange.
Honda's have advantage of fully supported base gaskets so they don't leak like XS Yamaha does
PJ
Did you measure the piston pin centerline to piston deck height? I've tried swapping piston brands in the past and that was always the problem. I could get the small end of the rod sleeved if necessary but the pin-deck height was always a hassle usually requiring more base gaskets or milling of the cylinder deck.

Thanks for the information.
 

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GS500, 17mm pin, 26mm center to top, domed about 6mm with squish band about 5~6mm wide
CB/CM 400 T, 17mm pin, 25.5mm center to top.
The late (3 valve) 450 has larger bore, think its 74mm flat top
Couldn't get to XS650 piston easily, but it is substantially taller for late model as the rod was shortened 10mm (probably around 35mm)
PJ
 
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