KZ400: upgrade front suspension

I weigh 160lbs I think that's light hehe

The 11-1115 springs are lighter and are recommended for the KZ400, but the manufacturer indicates it for the GS550 (2150kg).

The serial number 11-1109 is heavier and is recommended for the KZ440, but the manufacturer indicates it for the GS400, lighter and closer in weight to the KZ400/440 (185kg)

I don't understand.

Agreed, it's not very clear.

The 11-1115 has a 30/40 spring rate (in pounds per inch, or lb/in).
The 11-1109 has a 35/45 spring rate, so it's a little heavier/stiffer.
It sounds like they have the same physical dimensions, so they can work for the 400 or the 440.

I looked at the Progressive Suspension web site and they don't list any fork springs at all - just shocks. 

The installation manual PDF on Dennis Kirk for the 11-1109 seems to be for Goldwings: it references GL1000, GL1200, and GL1500. It also references a chart that is not actually part of the document.

I think you would be fine with either set of springs and making adjustments in the fork oil type.
 

I already ordered the 11-1109. As we say here, "ante la duda, la más tetuda" haha

The reviews on Amazon were good too, someone even talked about a KZ400.

Thanks for the advice and for your time, mate. When I have assembled them I will post reviewing the result.

You're very welcome - not sure how helpful I was though. And that saying is definitely a good one.

It would be good to see the results. Thanks!

I mounted the 11-1109 springs. The fork is fully extended with the empty weight of the bike, and it sags a bit when you sit on it. Dive under braking has been decreased considerably and overall the feel is stiffer (maybe too much, but I prefer that to diving).

Original springs measure 475mm. The new ones are 500, which adds a significant amount of preload and made it nearly impossible to bolt on the top plugs. But with the 11-1115 (softer) springs this would be exactly the same.

Happy overall. I doubt there is a better option for this bike today.

Feanor_twh wrote:

I mounted the 11-1109 springs. The fork is fully extended with the empty weight of the bike, and it sags a bit when you sit on it. Dive under braking has been decreased considerably and overall the feel is stiffer (maybe too much, but I prefer that to diving).

Original springs measure 475mm. The new ones are 500, which adds a significant amount of preload and made it nearly impossible to bolt on the top plugs. But with the 11-1115 (softer) springs this would be exactly the same.

Happy overall. I doubt there is a better option for this bike today.

Most manufacturers specify a specific spring preload but if your new springs are 25mm longer you would likely need to shorten your spacers...probably why you had some difficulty with the top plug.