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Not Really a Mechanical Issue, More Of A Question

1460 Views 5 Replies 4 Participants Last post by  bill440cars
While browsing 350 stuff on Ebay, I noticed a pair of 350 Honda sleeves and I remembered the 350 Powroll kits for the 305 Super Hawks. My question is, would it be possible to have a CB77 cylinder bored out to accept a set of 350 sleeves and would you be able to use the 350 pistons without having a problem as far as valve clearance and such? I'm probably just wasting time, but you never know. I DID see, over on the forums where there was discussion about building a 500cc engine out of the 305, that involved using the 450DOHC head and cylinder, but I don't have a clue what all is involved in doing that. Sure would like to see some deatails and photos on that! :cool:
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Bill -

Comparing specs on the two bikes, the 305 is listed as 60mm bore, 54 mm stroke.
The 350 is listed at 64mm bore, 50.6 mm stroke.

So it sort of feels like a bit af machine work might be required to allow the fatter sleeves to fit in to the lower crankcase. As I recall the old 350 overbore to the 305 was about 3mm or so, and didn't leave a lot of meat left.
But the stroke isn't all that much different - you might need to cut a bit off the bottom of the 350 sleeves so the 305 crank doen't whack them, but there's probably plenty of cylinder there to make up for the slightly (3.4mm) longer stroke.
Plus all the stuff that Mike mentioned......
I guess it depends on how bad you want to do it.

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