GS673 VS Tuned CB750 Thoughts please?

[Flyboy]

Or you could save yourself all the trouble and go and borrow Allie's box stock 750 and blow him into the weeds with that, and Allie's bike sure is a damn site prettier than any CB I have ever seen.

[Suzuki_Don]

Swap the cylinders and head form a 650 onto the 550 block resulting in 673cc's mated to a 6 speed transmission. This will start me at ~78hp (very close to a stock CB) prior to tuning

At that hp figure you are already way up on what the CB750 produces in stock form. The original CB put out 67hp, which is already 11hp down on what you have planned and you are on a much lighter bike which redlines at 9,500rpm as compared to the CB750s 8,000rpm. Then there is the better handling with you having a half decent frame.

IT IS A NO CONTEST -- take it from me.

[ashdricky]

At that hp figure you are already way up on what the CB750 produces in stock form. The original CB put out 67hp, which is already 11hp down on what you have planned and you are on a much lighter bike which redlines at 9,500rpm as compared to the CB750s 8,000rpm. Then there is the better handling with you having a half decent frame.

IT IS A NO CONTEST -- take it from me.

Don I am certain you are right, as my competition has cut many corners as far as design goes. It seems that this rivalry is more of a clash of personalities than a competition of machines. on an unrelated not is there any advantage to using 11K as a shift point? or dose this just over stress the motor?

second, now that I have the head off and valves out, is it possible to use valve springs from an 1100?

Third frankie fish(the competition) apearently has an xs1100, which he is doing up in a 'cafe' style. I am curious to know what kind of performance these bike carry? Is it out of the realm of reality to think i could build a 5/650 to beat it?

[TheCafeKid]

Don I am certain you are right, as my competition has cut many corners as far as design goes. It seems that this rivalry is more of a clash of personalities than a competition of machines. on an unrelated not is there any advantage to using 11K as a shift point? or dose this just over stress the motor?

second, now that I have the head off and valves out, is it possible to use valve springs from an 1100?

Third frankie fish(the competition) apearently has an xs1100, which he is doing up in a 'cafe' style. I am curious to know what kind of performance these bike carry? Is it out of the realm of reality to think i could build a 5/650 to beat it?

Those XSive 1100s are power monsters. But they shift like crap, they're heavier than a Sherman tank, and they don't handle all that well.
In a straight line, not a chance you'll beat it, unless he really sucks. But on a road course, you have the handling advantage clearly. With a big bike you have to sort of square the corners off. Point and squirt. It's harder to be smooth and clean and consistent. It's easier to overpower out of the corner as well. So if you can remain smooth and keep the throttle clean you should have him easily in the corners, and just have to hustle to fend him off in thenstraight.

[koolaid_kid]

As TCK stated, there is no way you could take it in the straights. However, there is a quirk with them which will allow you to blow it away in the twisties. It "comes on the cam" somewhere around 5-6k and takes off dramatically. (I ran one with my then new 78 750E.) So, if he stays low in the rpm range he won't have much power, if he stays on the cam he will have too much power, and if he passes through that band while leaned over it will go sideways on him.

[koolaid_kid]

As long as you do not pass redline, rev it up. Those smaller motors were designed to supply maximum power at high rpm.

[ashdricky]

so basically I need to focus on over all dynamics with my bike and ill have the potential to out ride him in the corners regardless weather he is on a 750 or xs1100. Ive been reading racetech's suspension tuning bible, hopefully this will send me in the right direction as far as suspension goes.

[850 Combat]

67 horse in a single cam Honda 750 is rated at the brochure. They were only 540 lb at first, and I have only ever located one old road test where one of them managed to get out of the 13's and into the twelves. I can find tests where it was outrun at the drag strip by a Sportster. (Cycle Guide 1972 Superbike Showdown) In fact, here is a link to it in my Albums:
http://www.thegsresources.com/_forum...pictureid=4372 The H2 was, of course, quickest in this comparison.

13.7 something in the quarter is a bunch slower than any test of a GS650 you will find.

In '69, they were not as slow, but still slower than the Norton 750, Trident, and H1.

http://www.thegsresources.com/_forum/album.php?albumid=727&pictureid=4370