CB250RS forks

[tychver]

Are they usually quite soft?

I bought this thing to learn on so I can't really comment on the handling. I had a friend with substantially more experience than me (he collects and races 70s Suzuki twins) and he thought that the suspension felt a bit soft too.

I was wondering if they had progressive springs and they got much harder?

Probably about time to PM TygerTung and xerxes...

[Robert Taylor]

Are they usually quite soft?

I bought this thing to learn on so I can't really comment on the handling. I had a friend with substantially more experience than me (he collects and races 70s Suzuki twins) and he thought that the suspension felt a bit soft too.

I was wondering if they had progressive springs and they got much harder?

Probably about time to PM TygerTung and xerxes...

They probably do have progressive springs but in fact 70% of the softness problem is because they have way too little low speed compression damping giving that initial mushy feeling. But conversely, when you ride over something abrupt such as a badly installed manhole cover it will feel like you are on top of a jackhammer! The fixed orifice damper rods flow too much oil for low velocity movements and choke off at high velocity movements. What is also in effect happening is that the forks are too readily blowing through the first part of their stroke due to woefully weak damping control and then arriving at the compressed part of suspension travel too early, ramping up the total compressed spring force. Oversimplistically, springs are about position, damping is about controlling that rate of change of position.
If you want excellence rather than mediocrity the solution is a set of properly installed ''emulators'', matched to springs rated for your personal height and weight and properly preloaded.

[tychver]

Thanks for the explanation.

If I decide to keep this bike for any length of time, I'll find a whole new front end for it, and have it set up properly.

[MGST]

I've got a 1985 Honda GB 250 clubman, which has ( I think ) the same mechanicals , forks etc. I am trying to decide whether to keep it or sell it, and amongst the list of "sell it" at the moment is the soft front end. Robert, How much would it cost to do whatever with the emulators and whatever else to sort it out properly ( I'm not into cutting corners ot save $$ ) - Ball park figure of course. PM me if you don't want it on here for the whole world. Thanks.

[Bonez]

If it's a standard SOHC CB250RS it wont have progressive springs unless they've been replaced (easy enough to check) and after 23 odd years use are probably a bit tired. Service limit for the springs is 477mm. Btw fork fliud capacity is 155.5-160.5mls if it needs replacing.

You can go RTs route(with the local support obviously) or buy aftermarket progressive items if you want through a local dealer or the internet.

[fridayflash]

my gb500 was much the same,i pulled them apart ,cleaned them up,
added heavier weight oil to maximum height and a bit of preload via
a few bits of plastic tube,and they were still crap.
save time and go with DR ROBERT'S suggestion

[tychver]

I've got reciepts for new springs, seals and fork oil from 2003. I don't know if I really feel like taking the forks apart and messing just yet. Only had it 3 weeks.

[driftn]

Great bikes man had one of those for my first and by god i did some miles on that thing. Thrashed the shit out of it up the fire breaks in welly, Down at the waimakarere rec area in chch (big jumps off the stock bank).

First thing i did was cam chain, Tensioners and rings could not kill it.


Always felt a bit funny and soft but that just adds to the character.
Best bike i have ever owned . Good times and even better memories.
Enjoy it mate it will go any where.

[Bonez]

I've got reciepts for new springs, seals and fork oil from 2003. I don't know if I really feel like taking the forks apart and messing just yet. Only had it 3 weeks.

The fork oil at least will be due for change. Take your time and have as much fun as you can on the thing.

Dogsnbikes has a couple he's dabling with.

[quallman1234]

Majority of road bikes are too softly sprung anyway, put a zip tie around the fork tube at the bottom for you (USD's) and if it does bottom out then you do have a problem.