cb500 front suspension upgrade

S

supercafe

Coast to Coast
hello all,

i recently have rebuilt my front forks. new seals, etc.
while doing this, i was reading through my manual and in the rear of it, there is a sectoin for performance upgrades. in it, it says that the cb500 and cb550 have no after market springs to stiffen them up. it says to stiffen up the springs, preload them with a 1 inch spacer, under the top cap and above the spring.
now i did get two 5/8 spacers, and install them, the fork is stiffer, seems to be working. i have yet to install oil, which i will install heavier.

this is a little trick that the vintage racers use for their bikes, it should be a reliable upgrade as it is in a manual.

what do you guys/gals think of this upgrade, i think it will and should work perfectly fine.
but it is always good to get other opinions.
so whats your that on this???????????????????????????
thanks,
later.
 
Well, keep in mind the info you read was probably published 30 years ago. There may be Progressive brand springs for your front forks.

Also, and you should confirm this perhaps with some of the guys at the SOHC4 forums, I seem to recall reading over there that the Fork Damper valves from MikesXS (intended for XS650 use) work with the 500/550 forks, but I can't be sure.

They're an involved install, but if you want the best performance out of your stock front forks, these are the limit I think.

http://www.mikesxs.net/products-19.html#products

"Front fork Damper Valves (Pr/2) Fits: 35mm. forks on 1977-84 XS650's. Tuneable Valves are installed on top of the front fork dampening rods and below the fork springs. The adjustable Damper Valve make rod style fork dampers perform like modern cartridge style forks."
 
thats an old mod, but it should work fine.

you may not need THAT much preload, especially for a street bike, but a stiffer front end will make turn ins happen a little more quickly.

expect a harsher ride.

personally i would have only put in one 5/8 spacer in each fork and then raise the forks in the triple trees about 5-10 mm or so in each. that would give a firm ride and a bit quicker turn in without sacrificing too much street-ability.
 
whats up,

thanks guys, Tim i have seen these adjusters, i will have to check those out. it would seem you guys know more than me on the interchangeable parts on these bikes so will be asking for help when the time comes...
Rocan, i did install only a 5/8 spacer instead of a one inch one. i also dropped the forks down as far as they would go, but they hit the clubmans, they go up about 1/2 to 1 inch past the tree.
i would like to drop it a little more but i would have to get another set of bars i believe.

any way, for now if this works that would be great, i will have to look into the adjusters and springs,
but i want to wait for the next winter season, my plans are to make the bike appear and run excellant with minimal money spent, and if it runs good next year i will do a complete tear down and do the powder coating, rims, spokes, engine rebuild, CHROME, CHROME, CHROME.
one more thing the top cap, under that it has a lock nut then the spring sits up against the spring.
i put the spacer inbetween the lock nut and the spring, seems to be the only place to add preload.
in the end the racers did this, but i have to ask. Will the springs take this, could they brake. they should'nt but what do you think???
any way, thanks again.
later.
 
Rocan said:
you may not need THAT much preload, especially for a street bike, but a stiffer front end will make turn ins happen a little more quickly.

expect a harsher ride.
Click to expand...

If you had ever ridden a CB50 you would know forks are way too soft.
1" preload is about minimum worth doing
You can fit CB750 springs.
Heavier springs will have same effect as raking out front end so making steering SLOWER unless you drop forks in yokes by 1"~1.5 "

PJ
 
Jp thanks man,
so the cb750 springs will fit in my cb500 forks.
does this stiffen up the ride alot or just make it better???
i never new that, would be worth looking into.
and no i haven't rode a cb500 before, just got the bike, same with 550 and 750.
so i don't know the way these bikes ride.
but thanks for the info man.
i'll have to source a set out.
thanks,
later.
 
750 springs are about 1" longer and designed for a heavier bike.
Use 15wt fork oil
Personally, I liked the heavy springs and extra ground clearance.

PJ
 
hey JP,
thanks for the info.
when i go for the full rebuild next year i'll keep my eyes open for a set of cb750 springs.
i like the lower look my self, but would like stiffer frt end.
any way thanks again.

what would you do for the rear springs??
could i install a stiffer spring from a 750, are they stiffer??
i want to stiffen the rear aswell, but don't want to buy the after market ones just yet.
you guys know more about the interchanging of these parts better than i.

thanks,
later.
 
750 shocks are about 1.5" longer than 500, best to find some the length you need and swap out springs from a heavier bike (need to measure wire diameter and length of springs)
I used Kawasaki 750 on my XS650
I can measure 650 stock springs and let you know wire size plus free length (and diameter where it mounts)

PJ
 
hey JP,

thanks that would be awesome.
the 650 shocks would be taller and stiffer?
if they fit into my shock that would be great, a cheap and easy way to stiffen up the bike.
for now that would be good.
if you could do that it would help alot.
do you have any of these types of springs???
any way, thanks a mill
later.
 
XS650 spring only is
1.6" inside diameter at top,
1.8" inside diameter at bottom,
wire is 0.300" diameter,
they are 9.5" long and have 13 working coils (one coil up from the bits that sit on shock ends)
Fitted length on 650 is 8.25"

PJ
 
hey, man.
thanks for the info.
fitted lenght is on the bike just sitting there?? 8.25"
and off the shock is 9.5".

so i need to measure the lower and upper parts to see if they fit on the shock seats?
they should be longer than the 500's. considering it is a larger bike.
i'll measure my fitted length aswell and see the hieght differance.

thanks again, for the info and help.

i got the frt shocks back together with the spacers in them and they feel stiffer already, with the oil in i think it will make a big differance.
anyway, i will check those measurements and get back to you.
thanks,
later.
 
i just ordered a pair of redwings for my 72 500K1 and was looking for progressives for the front end....

you say 750 springs work?

i had emailed a guy on ebay about a set and he said that they fit 750's and 550's.

i didn't order them because i was unsure if the fork internals were different.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=230400660485&ssPageName=STRK:MEWAX:IT#ht_3384wt_941

if someone tells me these will fit, i'm pulling the trigger.
 
hey man,

from what i have gathered, the cb750 springs are 1 inch longer than the cb500, 550.
also the spring bottom and top are the same, so in the end they should fit no problem.
the 500 base and top lock nut, seat the spring, so if the 750 spring has the same base, they will fit!!!

i instead of installing a spring that was 1 inch longer, i just installed a 1 inch spacer, same thing just a differant way of doing it.

so on the info that JP and others have told be, yes they will fit.
this is just on the info i have retainted.

any way, good luck, and if i didn't have other things to buy i would get a set my self.
later.
 
I think PJ (his name is not JP) is on to something. I personally run 1.25" preload spacers on my RD400 and I dropped the forks by 3/4". I would do as he recommended and run about 1.25" preload spacers and drop the forks about 1.25" Then see how you like it.

After you ride it a bit and decided you don't like it, then go for the CB750 upgrade.

--Chris
 
hey guys,

so chris you think that a 1.5 inch spacer would be better, i did install a 5/8 plus the lock nut, almost a 1 inch. i am afraid of braking a spring.
any way, love the bikes man.
thanks,
later.
 
you won't break a spring but they can get coilbound. (suspension moves about another 5")
I think your 'safe' to 1.5" spacer but its difficult to fit top nut :D
Fitting spacer isnt the same as fitting heavier springs though, it just means you loose the 'softer' part of multi rate spring and need more weight to get a 'straight' spring moving

PJ
 
hey man,

that makes sense.
i have a 5/8 spacer in mine right now, do you think it will make a differance or should i make up a 1.5 inch one????

i am going for the 750 springs, but at a later date. i just don't want any surprises with a passanger.
also what type of oil do you think???
thanks,
later.
 
Ride it around and see how you like it. For oil, try a medium weight and again, see how you like it. Changing oil and making different preload spacers is easy. It all depends on your riding style, personal weight, seating position, spring weight, unsprung weight, etc.

--Chris
 
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