Any performance CB650SC builds?

If it's broken or just needs tweaked

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daveyg
Posts: 10
Joined: Mon Sep 28, 2009 1:34 pm

Any performance CB650SC builds?

Postby daveyg » Fri Sep 14, 2018 8:29 am

Searching has been ineffective but I’m curious if anybody has built up a 83-85 650 Nighthawk. I got two of them for a song, one had a snapped rod, busted up both cases, really uglied up the crank, so I’m parting that one out, but after looking at the design from the inside it seems like the perfect candidate for modding, being that it has 4 valves per cylinder, ever so slightly oversquare bore/stroke, more or less flat top pistons, one piece crankshaft, etc. Seems like a pedigree that could build a good bit of power, but I can’t seem to even find aftermarket overbore pistons. Why does nobody capitalize on it? Just because it was the ugly duckling here in the US? Are the rods made of glass? I’ve got a set of cylinder sleeves that are 66mm bore (would go out to 68mm just to clean them up, and why not?) that would be a huge upgrade to almost 850cc whilst maintaining a short stroke, just like the modern sport bikes. Could upgrade the valves to stainless and go 1mm larger all around, coupled with some massaging of the ports should allow ample breathing for the increased displacement... I just don’t understand why nobody else has done it already.
DD:2008 EX650R
Project: 1985 CB650SC

cb650
Posts: 2953
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
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Re: Any performance CB650SC builds?

Postby cb650 » Fri Sep 14, 2018 2:49 pm

all it takes is money
Did you clean the tank out?!?!?!?!

daveyg
Posts: 10
Joined: Mon Sep 28, 2009 1:34 pm

Re: Any performance CB650SC builds?

Postby daveyg » Sat Sep 15, 2018 1:03 am

I have a milling machine and a lathe and access to a small foundry and 3d printer. All it takes is free time hahaha
DD:2008 EX650R
Project: 1985 CB650SC

daveyg
Posts: 10
Joined: Mon Sep 28, 2009 1:34 pm

Re: Any performance CB650SC builds?

Postby daveyg » Sat Sep 15, 2018 1:04 am

Just wondering why nobody else has done it yet (that I can find)
DD:2008 EX650R
Project: 1985 CB650SC


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