Wavey front end on a K6

Tried riding Courtys SV650S this weekend and was shocked. It scared the hell out of me.

Front end feals very light, very wavey and not under control. When cornering at higher speeds, the front end is trying to go everywhere but where you want his.

His front suspension is set to the softest setting I think (front yokes are on the highest setting.

Now bearing in mind I had a curvey, and now a bandit, with exactly the same front end, i was shocked how differently it fealt. My SV always fealt planted, my Bandit feels planted at the front, but his K6 SV is so wobbly.

Checking the suspension, mines still on standard settings and is on about 3-4 level on the front end.

Im thinking his front end is whey to soft, so should tinkering with the above and changing the setting help sort this? He'll be in for such a shock when its sorted.

PS, now i've ridden both, Curveys still rock over pointys

Pre-load will probably affect the feeling you're getting.

I've unscrewed the adjusters about half a turn, and I find it quite light like that. By that, I mean there's a section on my way home where (when I'm pushing hard) I can lift the front wheel in 5th gear!! When I'm not pushing quite as hard there's a definite lightness & a little head shake.

IMO, make's it more fun (but only when it does it predictably). If the front end wobbles are concerning you, worth checking the head bearings too. If these are shot, it'll give you no end of trouble.

[TSM]

Baph, do you think that pre-load affects the stiffness of the forks?

Originally Posted by TSM

Baph, do you think that pre-load affects the stiffness of the forks?

Yes, but only minimally.

By the very nature, preload determines how far up/down the "neutral unloaded" position the bike sits at by artificially compressing (or uncompressing) the spring.

I seriously doubt that any springs will give 100% the same movement at all given compressions. They will be progressive by their nature. So compress the spring before you get on it, by preload, and you will affect the movement of the spring (aka the stiffness).

Again, this is only minimal. But I've run with full preload, and with non. I've settled for a little adjustment over stock for static sag. Doing this adjustment definately does affect handling.

Sounds to me like the bike has all its weight on the rear aswell, if its feeling light - whats the setting of the rear shock?

Matt

Originally Posted by alpinestarhero

Sounds to me like the bike has all its weight on the rear aswell, if its feeling light - whats the setting of the rear shock?

Matt

Good point well made, my rear pre-load is quite agressively set (read: a couple of clicks up).

[TSM]

From all discussions had the term "preload" is flawed as is CDI to a curvey. In my mind "preload" should be called "sag adjustment" or the like.

As has been said before, a spring will compress under a given weight a certian ammount depending on the rating of the spring. When all wheels of the bike are on the ground holding the weight of the bike, the front forks are not at full extention, based on this if you apply "preload" to the springs essentialy you are pushing the spring, which if you remember compresses a certian ammount depending on the applied weight (for this instance lets say just the weight of the bike), now because of what ive just said, you turning the preload up you are just adjusting the fork height because the weight of the bike has not changed.

Bit of a raggled answer but you get the point, "preload" is not compression of the spring.

Unsure, i'll have to get him to check the rear. Whats the standard setting. Probably best to get him to change it back to standard and work from there.

But the difference between my 2 bikes and his, is amazing. Going round a long easy right hander on a dual carragewayt at 80, the front just wanted to go left, then right, then left, then right.

It didn't feel toooo bad under braking, but tbh, didn't enspire any confidence. I found myself going into corners very very very easy, and then just accelerating out of them to keep it stable.

Think his bikes still got low miles, sure its around 4000 miles odd.

Originally Posted by TSM

Bit of a raggled answer but you get the point, "preload" is not compression of the spring.

This begs the question; if by adjusting preload you are adjusting fork height, but not affecting spring compression, how is this possible?

The only way I could see, is that with no preload applied, there is a spacer that rests at "0" height (for sake of argument). When preload is applied, this spacers height is changed.

In theory, that wouldn't change spring compression, but in reality, it probably would. Very slightly mind.

Originally Posted by Daimo

But the difference between my 2 bikes and his, is amazing. Going round a long easy right hander on a dual carragewayt at 80, the front just wanted to go left, then right, then left, then right.

It didn't feel toooo bad under braking, but tbh, didn't enspire any confidence. I found myself going into corners very very very easy, and then just accelerating out of them to keep it stable.

Think his bikes still got low miles, sure its around 4000 miles odd.

Why tyres does it have on it?? I've found the profile difference between Z6 (rear) and PR2 (front) will cause similar effects to this (left/right/left/right waving under heavy acelleration).