34mm forks

[Dom]

The time has come to look at my forks which from the few miles ive ridden it, and I mean FEW miles, has shown them to be softer than soft.

I know everyone will say swap the whole lot for 35mm or larger forks but for now I'd like to keep some originality to the appearance and as larger forks has a load of knock on issues- wheels, brakes, steering stem etc. I'll at least try first.

The PO has fitted progressive springs buy I think quite a light oil so would the swapping to a heavier oil and adding a longer preloaded spacer get me some significant improvement bearing in mind I'm a lofty 10 1/2 stone?

 

[Grewth]

A bit of engineering skill is required here.
Remove the springs from the forks, buy a length of some decent size all-thread, and some nuts and washers.
Now use the all-thread to compress a spring until it goes closed coil.
And from measuring this, the stroke of the forks etc, you will be able to calculate the maximum length of pre-load spacer you can use.
Obviously you can't have the spring going closed coil before maximum travel is reached, it will damage the forks, and possibly you too.
Making a pair of spacers will cost very little, ditto for changing the oil.
If it's still too soft, see if a set of springs from a heavier bike will work.
Much cheaper than buying a new set of tricked up springs.
There you have it.
The tight-wad guide to suspension restoration

 

[arcticXS]

At least with regards to brake calipers, I think the 34 mm front ends are better, especially the -76 with calipers behind the fork sliders.
For the best setup for your weight, go to RaceTech.com and get linear springs of the correct rate , and some emulators. Doing that to my RD350 transformed the ride.

 

[Dom]

A bit of engineering skill is required here.
Remove the springs from the forks, buy a length of some decent size all-thread, and some nuts and washers.
Now use the all-thread to compress a spring until it goes closed coil.
And from measuring this, the stroke of the forks etc, you will be able to calculate the maximum length of pre-load spacer you can use.
Obviously you can't have the spring going closed coil before maximum travel is reached, it will damage the forks, and possibly you too.
Making a pair of spacers will cost very little, ditto for changing the oil.
If it's still too soft, see if a set of springs from a heavier bike will work.
Much cheaper than buying a new set of tricked up springs.
There you have it.
The tight-wad guide to suspension restoration

Thanks @Grewth , I like that idea as I'll not be thrashing about on this so adequate will be enough.

 

[arcticXS]

Adding preload does NOT increase the spring rate. However, shortening the spring will. So if there is sufficient travel "reserve" in the springs, cutting off some of (the tightly wound) coils will stiffen the spring.

 

[40north]

FWIW an XS of mine, a bike set up with dual front disks - a cafe-street-tracker with flat slides - an oddball a pal built from bike I gave him...

All that front brake and the typical yamaha soft front end makes her a dangerous bitch - I put 40 W in the forks. It helped. The tubes a bit worn too, and one's wet - need new gaiters. Longtime 30year ago I endoed her onto my knee because of the plunging with the recommended factory oil. It's dangerous. My gal has the linear cam adjusters set on hardest setting.

First time I took hydraulic forks apart I was lucky to have an experienced guide.

Best of luck....be sure to check the tubes for bend. On an evo I checked we found 0.030" bend...fixed with great caution.