Front end swap

S

ShaggyPit

Been Around the Block
looking into getting a modern front end for my 81 cb750 k. found a couple ads on local craigslist and checked the compatability on all balls racing fork conversions and they seem to match up. one of them is a 2003 sv650 complete front end.

my question is would this be a quality swap if the front end is in good condition? I ask this because it seems many people seem to go with GSXR front ends or from an R6 and more sport bikes rather than the sport tourers. The attraction to the sv650 is the price and it has dual discs.

any info would be appreciated thanks guys!
 
Keep in mind there is more to it than getting everything to bolt up. In the main, there are three areas to consider: The kinematics/geometry, the suspension (springing and dampening), and mechanics (bolt up).
The mechanics are straight forward enough, if not necessarily easy. The suspension does not matter for the most part until you drive it and start adjusting.
Unfortunately, changing the front end invariably means altering the geometry, usually not in a good way. People tend to think that the rake and trail are built into the frame so swapping forks and triples will just improve the suspension. The truth is that all the geometry elements interact with one another, and small changes can have important consequences.
Most "new" bikes have much stiffer chassis and can take advantage of a steeper rake angle. This creates a problem with the trail so the triples are invariably designed with a very small offset to make the bike reasonably stable. The upshot of which is that an old bike gets geometry it does not need or like despite getting better suspension. It's not usually a good trade off. If your bike handles poorly, writing a big check to Ohlins is not going to help.
There are quite a few suspension "calculators" on the web. Get one and plug in all the numbers from your stock bike and then with the changes you intend to make so you can see where you will be with the changes compared to stock. It will give you an idea of where your handling is headed.
 
I'm almost wrapped up on an 82 750K.

Running modern suspension is almost certainly going to drop your front end, a good bit on that bike.
 
Standard SV650 forks should actually work out pretty well on a 750. They're longer (iirc) than USD forks and the SV doesn't run as steep a head angle as a true sportbike.
 
Like anything though, do the research. Find the rake and fork length numbers from an SV and compare them to the 750. As far as fork dampening and whatnot, your CB is pretty close in weight to the SV (if not a hair heavier) so you should be ok there. Next big question is what to do about wheels though. Remember that the SV runs a 17" wheel so if you run that you've already altered the CBs rake and trail.
 
thanks von,jrod, and jp for all your inpput! super helpful and will continue to add this info to my research!
 
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