kz550 frame compared to a kz750 dimensions. please

I just got a kz550, and got it mint for 500 bucks. I got gsxr forks 600-750 year 06-07 for 250. Im looking at a kz750 stem conversion kit for the gsxr forks. Im trying to figure out the dimensions between the kz550 neck and the kz750s neck sizes. So if I got the conversion stem and pressed it into my gxsr forks, im hoping it would slide into my kz550s neck the same as it would a 750s. Im really trying not to buy the wrong piece, so if anyone could help me get this information I would be greatly pleased. I know kz550 is hard to work with but Im not giving up on my first build, iv already made it this far. Also if there is any suggestions I willing to listen. Thanks

What KZ750 is it? year & model type or letter designation.

Look up the taper roller bearing kits for both bikes and see if they are the same.

That was a nice little bike.
Steve

All Balls Racing has a bearing swap lookup, but you'd still need to know the length of the steering head &/or triple tree stem, so specific model info is still needed. The 550C uses the same tapered bearings as most 750s.

Why not use the 550 stem?

+1 Swap the stem if you can. That's what I did on my 550/750 front end conversion. I used zx750 3 spoke wheels with 37mm forks on the 81 550 twin shock, Weld at bottom ground off, 550 stem pressed out and pressed into the 750 yokes. This needs to be really precise work so get someone good onto it.

Really best to swap a front end complete: yokes, forks, wheel spindle, calipers, discs. Trying to fit the gsxr forks onto kz wheel and brakes can be done but not really for a beginner, also it sort of defeats a lot of the point of upgrading to a modern front end imo. Mounting clocks, making caliper mount plates , changing wheel bearings to suit the gsxr spindle, nothing will fit together.

If you source the other GSXR front end bits (expensive,front end smash parts always in demand, and the import 250 are pretty rare anyway) you will be altering the frame geometry quite a bit. kz550 are leading axle forks, gixxer conventional, and you are going from 19" front to a 17" wheel with the gixxer forks likely shorter than the kz item.

Either way you still need to sort the different speedo ratio, risers for the handlebars, fit a longer sidestand to compensate for the lower ride height...quite a lot of work to do it right. Then you have a mis-matchtched front and rear wheels - I'd want a matching rear too, plus disc and caliper and then you need to see if it will fit in the 550 swinging arm, keeping the chain line offset correct...


Not trying to pour cold water over your ideas, just temper it with the reality of the situation and what is involved to do this conversion right. And that's just the engineering, your reduced trail and fork offset could screw up the handling - if the front is lower after the conversion, you have also tightened up the frame castor angle and further reduced the trail.

Thanks for the info man. Im gonna keep all that in mind. Im gonna get this put together with information like this.

The kz650 conversion kit fits the neck just fine. Love it.