new member and 1st time bike owner, 74 kz400

Hi my names Jeff and I'm from NJ and just bought my 1st bike a 74 kz400 for $400...I wanna make a bobber and have a good idea how i want it...my question is I want to extend my swingarm about 4" and don't know how to go about doing it...I read that a LTD swingarm is longer but Idk how much or if it would bolt up to a 74...if anyone knows where I could get an extended swingarm, or if there's another one thats longer that would bolt up to my bike I would appreciate the incite...and if neither of those are possibilities how do I extend it myself or if anyone knows someone that would do it for me...thanks again - Jeff

From what I remember of the last 76 kz400 I had the swingarm was pretty flimsy looking at best in stock form to say the least,lengthening it would probably make the situation worse without a serious bracing job.
What are you planning to do with the bike?
Whats the width of swimgarm pivot tube?

Have you considered the possibility of actually learning how to ride and getting some saddle time before venturing into motorcycle design, engineering, and fabrication? :whistle:

I'm not sure what the width is, I haven't measured it yet....just to give ya and idea of what I'm tryin to do here's pictures...the blue one is my bike and the black one is what I want it to look like...




I'm going to ride the bike as is until I get all the stuff I need to make it a bobber, I just wanna know how to do it so when i do work on it I know how.

Well I can pretty much guarantee the shocks on the black version may as well be struts as theyre laid out they wont do much for ride quality! :sick: :woohoo:
And that swingarm is going to flex severely if those shocks do actually move any

So if I do figure out how to extend the swingarm I should just go with struts?

Id find a swingarm with bigger tubing if you do it,and move the shocks forward about 4" on the swingarm you they can actually operate.
Picture the swingarm as a big arc with pivot bolt as center and the axle as the outside of circle,it wants to operate in that area.
Then you have to figure an angle that the shocks will allow that to happen while they expand and compress as needed at same time.
Make sense?

Yeah, thank for the help when I start building it ill post pictures of how it's all going.

Measure the width between the frame tubes and the length from center of pivot bolt to end of axle and post it up here so we can get some ideas of what you need in the future

Howdy. The KZ400 is a neat motorcycle. You should go thru the bike & do all of the maintenance stuff, getting it in perfect riding condition. Be sure to refurbish the Fr brake & replace the Rr brake shoes if they are old - even if the linings are plenty thick - replace them. And ride it. Then sell it late for something bigger. A refurbished stock vintage bike might be easier to sell than one that has been modified. If the frame is cut, the value is probably decreased by $500. Once cut, it is ruined.

That black bike is absolutely NOT how you want to lay out the rear shock. That rear geometry leads to a regressive suspension. You want a progressive suspension... where the shocks put more force on the swingarm as it moves upward. In extreme cases, a geometry, like on the black bike, can just collapse when a large enough bump is hit.

As the swingarm moves upward, the swingarm and shock should get closer to a right angle... not farther, as in the case of the black bike.

A strut in place of the shock will work, but will also be work to ride.

I better find a 4-hundie before they're all gone!