Topic: Need some advice on rear shocks for '82 CB650SC Nighthawk

[fizzlebottom]

Current shocks are original 40 year old pieces, 42k miles on the bike. I doubt they're very healthy anymore, so looking at replacement options.

The shock assembly and its associated major parts are all unique snowflakes in the Honda SOHC/4 world (https://www.partzilla.com/product/honda/52400-460-841?ref=b0390a0f4fbf14afb573c20674e7d55b7424d86a).

Neither IKON nor Progressive Suspension have exact listings for replacements, so I'm left to figure it out for myself. Parts N More has some 365mm shocks with "progressive heavy duty springs", but at $96 I know I'm not getting much in terms of quality. So far as I can tell, 365mm is about close to the originals. I measured mine between 349-352mm, but they're on the 4th preload setting out of 5. Not sure if that impacts overall length, and I don't have a preload adjuster spanner.

Aside from the overall length from eye-to-clevis, I have no clue what I should be looking for regarding spring rate or other attributes. I'm not well versed on suspension.

I don't race the bike and I'm probably barely breaking 135lbs. No passengers. Would it be best to just contact IKON and Progressive and see what packages they can slap together for me? Or are there other options I should be considering?

[70CB750]

I put Hagons on Red and I am very happy with them. Red is a sidecar rig and I clock at 280 pounds - got the stongest spring Hagons and leave them on second  to last setting.

[fizzlebottom]

Where did you get your Hagons and how did you land on a specific setup? They sure don't seem to be as easily sourced as other manufacturers.

[Doobie]

https://www.ikonsuspension.com/product/7614-1296/

[70CB750]

Where did you get your Hagons and how did you land on a specific setup? They sure don't seem to be as easily sourced as other manufacturers.

Took me forever to find it, but I bought them from Dime City Cycles:

https://www.dimecitycycles.com/search?q=hagon

[fizzlebottom]

https://www.ikonsuspension.com/product/7614-1296/

Sure, I've seen this several times. The problem is that the list of bikes they fit is extremely broad, covers several different lengths, and is completely missing what I need (CB650SC). I'm going to call them tomorrow and see what they can help with.

Took me forever to find it, but I bought them from Dime City Cycles:

https://www.dimecitycycles.com/search?q=hagon

Yeah the bummer here is that no such Dime City lists no Hagons for my bike, or any SOHC/4 CB650 for that matter.

If I really wanted to go with Hagons, I think I'd have to give BellaCorse a call and see what they can setup for me.

So far that seems to be the best path forward: Call or email IKON, Progressive Suspension, and BellaCorse and see if they have some better insight on a good shock combo.

[pekingduck]

The length measurement needs to be made on the centerstand, if you have one.  It is the maximum extended length, regardless of preload position.  If you don't have a centerstand, then have someone measure the length of the right shock as you stand on the left sode and pull up on the right grab rail to extend it fully.

Too short a shock may cause the pipes to scrape in cornering, and also make it harder to put it up on the centerstand.  Too long, and it may make it be too tall at a stop, and while it may help make it easier to put up on the centerstand, it may not allow the tire to clear the ground, depending on the tire size.

Your 350mm is about 13-3/4", while 365mm is about 14-3/8". 

Progressive Suspension lists the 14-1/4" 1205BG for your model. I would recommend the medium spring option (90/130 dual rate). They can be had in black (DS310031) or chrome (DS222015).

They can be ordered through any bike shop because they are sold through Parts Unlimited/Drag Specialties, which every dealer orders from.  Make sure you know the spring rate, as this shock size also fits much heavier 750/900 dohc and CBX.

[Kelly E]

Progressive also has a 70/120 rate spring that fit the series 12 shocks. It is listed for a different shock model, I used a set on the 77' KZ 1000 because I only weigh 125lbs. I had to get the springs from JP Cycle, the Progressive tech guy sent me to them because they were out of stock.

[pekingduck]

I agree with Kelly E above, 70-120s are probably more suitable. And I had listed Parts Unlimited/Drag Specialties' part numbers that correlate to Progressive's p/ns.

[fizzlebottom]

Interesting, and I think I agree. I used one or two supposed spring rate calculators, plugged in numbers they asked for, and mostly came out with a 90lb spring rate being correct for my setup. Progressive's 75/120 spring (03-1394B) would probably fit nicely for that. Parts Unlimited shows heavy duty springs (105/150) as correct for my bike, but also that Standard springs are recommended for "bikes as sold new, excluding any accessories, rider weight under 200 lb. (EU: 90,72 kg) and passenger use limited to under 50% of the time." And the 75/120 is the only standard duty spring in the group of options I saw.

I'm going to give Progressive a call tomorrow and see if they can confirm that selection, then hit up one of my local shops to order the parts.

Thanks for the thoughts folks. Parts are usually super easy to choose from, but suspension stuff is way outside of my wheelhouse. What a can of worms to open.

[fizzlebottom]

So I went a little against the grain. I rung up Progressive Suspension and found that they DO have my bike listed, but it wasn't where I was expecting. They show it as 650 Nighthawk instead of CB650SC Nighthawk. Anyways, for a standard weight spring they suggest 105/150 and 120/170 for heavy weight, which seems very different than recommendations here.

I ordered their 14" 12-series absorber and the 105/150 springs from my local shop, and they said that if I don't ding them up during installation and testing then we can package them back up and return if I find that they're entirely too stiff. Regardless, if I'm out $88 for a set of springs and I have to get softer ones then I'll eat the cost or try to resell.

Will report back with my findings. I'm excited for some fresh rear suspension.