79 kz400 rear suspension?

My 79 kz400 is currently being worked on so it can work properly mechanic wise. I noticed that my rear shocks are all rusty so I wanted to purchase a pair of rear shocks.
What's the OEM sizing for the 79 kz400 B rear shock?
What aftermarket shocks are kz riders using out there?
What do you think about these
m.denniskirk.com/emgo/classic-shocks-17-...84997.prd/584997.sku
And why do I see people using different size mm shocks? What does that do to the ride?
Has anyone used those dimecitycycle no name brand rear shocks that go for $90? Are they good and what size should I get?

Thank you in advance for sharing your input !

Shocks, like other suspension components and well about anything else for a motorcycle, are one of those things where "you get what you pay for".

I believe the stock shock length for the KZ400s is about 12.5 inches which is around 320 mm. You can go a bit shorter if you're a smaller rider and/or you want the bike a little lower by also lowering the front end a little by running the fork tubes up through the top triple a bit. You can also go a little longer on the rear shock to raise the back end up and make the bike a little quicker turning (twitchier). But for the most part you'll want to keep the stock geometry roughly the same (lower it the same amount in back as front) unless you know what you're doing and want to experiment a little.

I'm not a fan of those inexpensive dual-spring shocks but I've never run them so my opinions are purely based on looks - I think they look cheap. There are a lot of guys who use them though.

You can still get Progressive shocks for these bikes and they are not too expensive. Hagons are another option. You may be able to find an older set of Koni or Ikon shocks that are rebuildable and have them serviced. Another option is to find a pair of takeoffs from another bike. I know other people who have used Harley (particularly Sportster) takeoff shocks and had decent luck with them for something pretty economical. I've also read of a few people who have used and been happy with takeoffs from a KZ750 twin.

For cheap shocks I've been happy with a couple pair of something like these Girling reproductions and I like the looks of them. The first pair I bought were non-progressive for my 76 KZ400 and I think I went with 11.9" and lowered the front end a bit too. They work well enough for me for weekend cruising and mostly short rides. The second pair I bought are the ones linked and are progressive and a little taller than stock, they are for my 78 KZ400 scrambler project where I wanted a little more height/clearance at the rear. Both are a little stiffer than the stock shocks but I'm a little over 200 pounds and after adding gear probably pushing 230 so I needed a stiffer shock.

www.tecbikepartsusa.com/Triumph_Bonnevil...s_340mm_p/t-sh18.htm

But while I've been happy with them they are still cheap shocks and you can probably do much better if you spend a little more money.

Thank you for the write up, Very helpful. I'm 6 foot and weigh 205 and I would like to keep the bike as close as stock geometry as possible. But I will be riding my wife on the back here and there so that's another 130 pounds. So should I keep get shocks at the same stock height or go taller ? And how much taller? My front forks are stock height.

That link that you sent, is it an exact fit? Even though it says it's for a triumph, will it need some modification to fit?

Also found these for the kz650 on the same tec site

www.tecbikepartsusa.com/TEC_brand_KAWASA...ks_p/j-sh05-k650.htm

Will it fit?

I'm also 6 foot and weigh about 215 pounds. My wife rides on the back so that makes my total and your total weight nearly identical. You do NOT need longer shocks; you simply need better shocks. The stock shocks were not high quality units, and buying discount shocks is a mistake unless you plan to sell the bike immediately. Cheap shocks are trash. I bought my KZ650 new, and the shocks were worn out in less than 10,000 miles. I have been using a pair of Hagon shocks for the past 8 years (14,000 miles) and they still look and work like new. If you look at the bottom picture at davequinnmotorcycles.com/cgi-bin/webc.cg...GON_TWIN_SHOCKS.html mine are the type marked #4. They have stainless steel shrouds and bodies. Contact Dave Quinn at that link. He will set up the shocks with the proper spring weight for your weight, riding style, etc. I found him to be a really great guy. Here's what mine look like on the bike. Ed

Very nice. And not that expensive at all if you go with black body - a little over $200. I know where I am getting my next pair of shocks.

Thank you for all the info, has anyone ever tried the emgo suspensions?