Mono Shock Question

[dimka pdx]

Hi all,

I am currently in the process of building a '79 XS650 project bike...and honestly, I have no idea if this will end up more like a bobber or cafe. One of the things I know I will want on this bike is a mono rear shock. At this time, I have modified the frame to be a close reseblance to the Brat Kit, and modified the swingarm to use a mono shock I purchased on eBay from a CBR600RR. As it sits, and even when adjusted to the softest setting, the current suspension is wayyyyy too stiff. To double check it wasn't the design, I installed the stock shock int he position of the mono, and everything functioned beutifully...but way too soft now.

Do you guys have a recommendation for a good mono shock? I am not looking to spend more than $100, and buying used would be just fine. I was thinking of buying an R6 rear shock, but I imagine that it would be just as stiff as the 600RR one.

PS - my current setup mounts the shock less vertical than stock crotch rocket bikes. The attachement point on the swingarm is connected to custom bent tubing that is above the tire (raked forward). The frame side is mounted underneath where I think the front of the seat will end up being.

 

[XSJoel]

I am not real hip to it, I would look at a shock from a very light sport cruiser. Just throwing it out there. Like an old GS500E or the sort. Just an idea. It's all I got.

 

[MrBillohnooo]

If ya can find a local dirt track car racer or shop that has a rate checker have em do a spring rate check on the too soft and too stiff ones.......and just swap springs to the rate ya need for it. Ya already know a too soft and too stiff rate. Lots of spring lengths/ rates available out there.

 

[durgam_K]

Are you also using the stock Shock linkage set up. If not, its going to be a dramatic change in 'feel'.
The spring will have a stiff rate, but the shock, and linkage is all engineered together, to function as a unit of levers, fulcrums, and compression. these components were all designed to work together.
Another factor may be that your distance of shock to axel may be way different than stock (shock and swingarm setup from donor bike ).

think of it as putting a bag of sand in your truck bed for the winter. You wont benefit much if you put it right behind the cab. The idea is to move the weight closer to the axel, for traction. By moving the swingarm shock mount closer to the pivot, will have a softer ride, than being placed on top of the axel.
If this isnt making sense i understand. Im starting to ramble.

 

[dimka pdx]

Are you also using the stock Shock linkage set up. If not, its going to be a dramatic change in 'feel'.
The spring will have a stiff rate, but the shock, and linkage is all engineered together, to function as a unit of levers, fulcrums, and compression. these components were all designed to work together.
Another factor may be that your distance of shock to axel may be way different than stock (shock and swingarm setup from donor bike ).

think of it as putting a bag of sand in your truck bed for the winter. You wont benefit much if you put it right behind the cab. The idea is to move the weight closer to the axel, for traction. By moving the swingarm shock mount closer to the pivot, will have a softer ride, than being placed on top of the axel.
If this isnt making sense i understand. Im starting to ramble.

No...this is super helpful!

You are right in that I am NOT using the engineered linkage, but rather just shock eyes on both ends. I'll need to get a new shock before I can mount it closer to the pivot, as the piggy back resevoir on the 600RR shock sticks out sideways...weird design but looks awesome with the current configuration.

If I did decide to use the current configuration, is there a way to identify a shock with less spring rate/dapening, that would still be sufficient?

 

[skid]

You should try using a shock from a bike that does not go through a linkage. Like a Ducati Monster or Aprilia Shiver. They are mono shock bikes with a single pivot. I am doing something similar and am using a monster shock. Plus there is no reservoir to get in the way.

http://www.motorcyclistonline.com/features/122_0812_ducati_monster_696_vs_aprilia_shiver_sl_750/photo_06.html

 

[durgam_K]

Skid is right! Use another shock form a similar set up as yours, of find a shock from a way lighter bike, (250 ninja, or maybe even a dirt bike, they have linkage but may be a easier spring rate )

 

[dimka pdx]

You should try using a shock from a bike that does not go through a linkage. Like a Ducati Monster or Aprilia Shiver. They are mono shock bikes with a single pivot. I am doing something similar and am using a monster shock. Plus there is no reservoir to get in the way.

http://www.motorcyclistonline.com/features/122_0812_ducati_monster_696_vs_aprilia_shiver_sl_750/photo_06.html

This is awesome advice...

There isn't much luck finding an Aprilia Shiver used shock, but plenty of Monster shocks. What year/model should I be looking for? Some of them on eBay look to come with a dogbone attached, so I am guessing those are the wrong ones.

 

[skid]

The new monster 696 has a single pivot. There is other options in bikes as well, the shiver and monster are just a couple. You could look at the kawi 650 ninja, kawi versys, some buells and I'm sure there is more. I can not guarantee any of these will work that's up to you to figure out.

 

[Ngreen]

I am having the exact opposite problem. I've tried 3 shocks and they are all way to soft. I've tried a ninja 250 shock, a bandit 400 shock, and a shock Off a larger kawi bike. No matter what I do they are way to soft. I have them mounted almost vertical under the seat straight down through the gap between the front of the tire and the swingarm. The bottom mount is hard mounted to the bottom of the swingarm. Any suggestions? I would much prefer to stiff. I don't want much travel, I just can't have a hardtail because my back is messed up from a previous dirtbike accident w a tree.

 

[MrBillohnooo]

You might try your local stock car racing supplier. You should be able to take them your spring off your shock, have them test it for rate and possibly get you a stiffer or softer one. I have done this on dirt bikes with good sucess. I weigh in at about 260, and stock shocks are usually waaay too soft.