Topic: Correct rear suspension length

[Floshenbarnical]

Hi there friends,

1977 CB750F2, curious what the stock rear shock length is supposed to be? I want to make sure the bike is as close as possible to its original configuration to ensure it handles correctly, but there are many eye-clevis shocks out there and the manual doesn't have the original stock length listed anywhere.

[seanbarney41]

Iirc, right around 13-1/8", 13-1/4"...have run 14" from 80's cb900f and it did sharpen up the turn in and was still stable at high speeds

[Floshenbarnical]

Do you think I could run 14” as a 200lb 6’3 man? Or should I get stock lengths but specify my weight so the manufacturer can adjust pre-load

[HondaMan]

Do you think I could run 14” as a 200lb 6’3 man? Or should I get stock lengths but specify my weight so the manufacturer can adjust pre-load

It would likely be fine: the OEM spring rate was in between 110-115 lb/in (Honda was vague about this) on the factory shocks: we used to 'call it' 112 lb/in. I know from experience (I am 140-ish lbs, ride with a Vetter and tourpak, plus Krauser detachable saddlebags when touring) that 120 lbs/in rate (2nd preload position) makes for more fatigue on real long rides, like 500+ mile days. The 110 lbs/in rate rode better (Betor shocks, which I rode for 35 years) using the #3 or #4 preload position with heavy (1-up) loads. It took #5 preload when adding my wife (she was 110-ish lbs then).

And, a personal note/opinion/rant: I HATE the way the bike handles with progressive rear springs. In the mountains it will change lines when pulling hard out of deep corners. I still can't find straight-wound 110-lb springs for my new(er) ORCA shocks (which Terry Down Under found new for me!). The damping is tops, the spring rate SUCKS as "90-120 lb/in rate".

[seanbarney41]

Do you think I could run 14” as a 200lb 6’3 man? Or should I get stock lengths but specify my weight so the manufacturer can adjust pre-load

shock length affects rake and trail, spring rate should be adjusted to weight of the bike and rider, pre-load is used to adjust sag
so...no matter whether you get 14" or stock length you should specify the weight of your bike and yourself (and whether you intend to regularly carry luggage and/or a passenger)