Question regarding ride height and fork squish

[EvenmoreXS]

Quote from 5Twins:

"If the bike spent most of it's life parked on the side stand, that can do it."

regarding squishy forks and low ride height.


I bought some forks...1980's 35mm.... from a bike that had very low miles....Less than 3k if I remember correctly......The bike was part of a private collection....Forks looked as close to new as you can get.... I installed them and have been riding around for a couple months now with no issues with function.

The difference between these forks and the old forks is the ride height and the squish factor. The new forks are much softer and ride lower. They don't bottom out but I keep dragging my side stand on speed bumps and the like. She does dive a bit under breaking but again,,....does not bottom out. Cant be far away though....

I think some new fork fluid would help with the squish and fork travel....but I doubt it would help with the ride height. I don't really want to do spacers.......

Would the bike being on a side stand most of its life compress the springs and cause this lowering......If so.....I think I would consider replacing the springs with the springs from my old forks.....1981 35mm......... because they were a bit better height.

I changed the forks due to a need to replace the fork seals in my old forks but the new forks were a good price and it was worth having an extra set on hand...So i did it.... Forks have been fine but Im concerned that I may eventually meet a hump or driveway I wont be able to get over.

So,

Are these springs interchangeable...80's and 81's.....? Is this recommended or not?

Where would you guys start....?


Also, first time fork worker here.....I can drain the forks from the drain screw on the bottom and once emptied just refill with new fluid from the top with the caps off....7 to 7.5 oz range of fluid.....about 6 inches from the top.....I will likely do fork oil instead of atf or motor......

Thanks everyone. I look forward to a plethora of excellent replies...

 

[gggGary]

All springs 79 up are the same.
Yup drain, pump a few times refill from the top I like Griz? WER? using a suction pump and measured tubing to set the oil height.

Spring sag is common on any bike that's 40 years old.

79 up forks also have the screwdriver adjustable top spring stop have you messed with that?
I have a local Harley guy looking for some sporty springs to try. I used a set of the mikes emulators and think they improve the ride but I really should mess around with their settings some too.
This Yamaha 2F0-23141-00-00 SPRING,FRONT FORK is used on these models and components:

1978 XS650E FRONT FORK XS650E - E006501- - F
1978 XS650SE FRONT FORK
1978 XS650SE-11 FRONT FORK
1978 XS650SE-114241 FRONT FORK
1979 XS650SF FRONT FORK
1979 XS650_2F FRONT FORK
1980 XS650G FRONT FORK
1980 XS650SG FRONT FORK
1981 XS650H FRONT FORK
1981 XS650SH FRONT FORK
1982 XS650SJ FRONT FORK
1983 XS650SK FRONT FORK

 

[TwoManyXS1Bs]

Have you considered a geometric spring comparison? Lay the new springs next to the old springs and compare wire diameter (with a caliper), coil count, coil profile (straight or progressive), free length...

 

[EvenmoreXS]

Thanks Gary, I will try the fluid first and see how that affects the ride. Maybe less travel would keep me above the bumps.

I have not adjusted the top spring stop, but will look for some threads on that. Good idea.

Thanks

All springs 79 up are the same.
Yup drain, pump a few times refill from the top I like Griz? WER? using a suction pump and measured tubing to set the oil height.

Spring sag is common on any bike that's 40 years old.

79 up forks also have the screwdriver adjustable top spring stop have you messed with that?
I have a local Harley guy looking for some sporty springs to try. I used a set of the mikes emulators and think they improve the ride but I really should mess around with their settings some too.
This Yamaha 2F0-23141-00-00 SPRING,FRONT FORK is used on these models and components:

1978 XS650E FRONT FORK XS650E - E006501- - F
1978 XS650SE FRONT FORK
1978 XS650SE-11 FRONT FORK
1978 XS650SE-114241 FRONT FORK
1979 XS650SF FRONT FORK
1979 XS650_2F FRONT FORK
1980 XS650G FRONT FORK
1980 XS650SG FRONT FORK
1981 XS650H FRONT FORK
1981 XS650SH FRONT FORK
1982 XS650SJ FRONT FORK
1983 XS650SK FRONT FORK

 

[EvenmoreXS]

Have you considered a geometric spring comparison? Lay the new springs next to the old springs and compare wire diameter (with a caliper), coil count, coil profile (straight or progressive), free length...

Not yet, but if I do swap the springs expect some pics and measurements....

 

[Max Midnight]

I would suggest that you will find it difficult to get a good feel from the front end whilst retaining OE springs and damping.
They weren't exactly the best when new and wouldn't have improved over the subsequent 34 years.

Changing oil (viscosity) will influence the high speed damping (i.e. when the suspension compresses quickly) but will do little for low speed damping (where the suspension moves slowly) or ride height.

So what to do?
You could compare the spring length of your current and original forks. However, that is only half the story as you would also need the compare spring rates as well to get a more meaningful comparison.
In addition, you would also need to establish how much they compress when the load of the bike and rider are added.
Whilst you say that you 'don't want to spaces' this is the only way you will be able to get the correct static sag, i.e. how much the forks compress from fully extended when the weight of the bike and rider are added. Whist this may not transform the handling you will at least be getting the best of what is possible.

If you want to take it to the next level and are prepared to spend some hard earned then upgrading the springs and fitting emulators will make a significant improvement to the ride quality and handling.

In summary, I would start by replacing the oil with the recommended volume and viscosity of oil AND set up the static sag between 25 & 32 mm.

As they say oop narth, "Thee don't get owt for nowt"

 

[EvenmoreXS]

Max, you early bird....

Thanks for the reply. Moving to my new house now, but once all set up Im going to tackle this.

Thanks everyone.

 

[Max Midnight]

Max, you early bird....

Not if one is in the UK!

 

[5twins]

Your adjustable top caps have two stiffer positions available, each adding 10mm of preload. This gives a total of 20mm or just over 3/4". If that's not enough, I recommend you add 1" tube spacers. They will give you about 25mm of initial preload, about 1/4" more than what's available to you now, with the ability to add in 20mm (3/4") more through adjustments.

Yes, change the fork oil, and use about 7 ounces (about 1 ounce more than the stock spec). That alone gives a much improved ride and greatly reduces brake dive. Since you have extra forks now, I would suggest Minton Modding the damper rods in your extra set. This greatly improves the fork response to the little bumps and makes the forks work much better for normal riding around.