Forks on the right spot?

[Hooli]

What happens when you buck in 644.0 ml in each leg like I did.

Depends how well you emptied it. it's always been almost exactly that amount for me, it's just the air gap is a bit more accurate.

My limited understanding is a smaller air gap stiffens the forks a bit as the air is forced to compress more so assists the spring. I guess too little air gap & you blow the seals out over the first big bump.

[Irish in Oz]

What happens when you buck in 644.0 ml in each leg like I did.

Depends on the amount of old oil remaining in the fork leg.

None.

[Hooli]

It'll be close enough then.

I partly do the air gap as I find it easier to get accurate than looking for a flat surface to balance my measuring jug on.

[Eric GSX1400K3]

I fit the fork in my vice or portable work stand, make sure its vertical in both planes, then fill 1/2 with oil, actuate the damper rod to get all the air out, then top off. I use verniers locked at the required air gap and set them across the top of the tube to get them spot on. Cant remember whether the spring goes in before measuring the 108mm or not, but the free air volume does affect shock performance.

[Hooli]

Spring in afterwards & forks measured fully compressed, from memory.

[Eric GSX1400K3]

Sounds correct mate, so the airgap as measured takes into account the oil volume displaced by the springs.  Less air (more oil) would lead to increased pressure and more likely to blow seals out, heavier oil adds extra damping as it takes longer to get through the valves and ports.

[Coopz]

You need to establish if everything is standard. Dropping forks through speeds up steering but reduces fork travel. If they're stock and you weigh 90kg+ go with 10 weight oil as per Greg's suggestion.
It's a dark science the suspension 😵�💫😵�💫

I had a red/black K5 10 years ago, spent $350 having a race shop set it up for me, honestly felt exactly the same after they put thicker oil in the forks and changed all the rebound and dampener settings.
 I just think going from a sporty ZX12R to the 14 I was just expecting similar road manners.

[Kiwifruit]

My old fork oil was so mucky I kept rinsing it all out until the kero ran out clean. I hung them overnight to get everything out before refilling.

[Hooli]

I've had to slosh forks out several times with petrol to get sludge out the bottom before.

[Roo]

You need to establish if everything is standard. Dropping forks through speeds up steering but reduces fork travel. If they're stock and you weigh 90kg+ go with 10 weight oil as per Greg's suggestion.
It's a dark science the suspension 😵�💫😵�💫

Correct on dropping forks through yokes speeds up steering GSX. But Travel is affected by spring and or oil  No ?  and preload ?  or is my old brain fading ??

[grog]

Agree Roo, exact same travel, just located diff position in yoke.Just means bike is higher or lower.

[Hooli]

You need to establish if everything is standard. Dropping forks through speeds up steering but reduces fork travel. If they're stock and you weigh 90kg+ go with 10 weight oil as per Greg's suggestion.
It's a dark science the suspension 😵�💫😵�💫

Correct on dropping forks through yokes speeds up steering GSX. But Travel is affected by spring and or oil  No ?  and preload ?  or is my old brain fading ??

Ahh yes BUT.....

Changing the trail of the fork affects the effective spring & shock rates.

Remember the old Brit bikes (Velos come to mind) where you could adjust the rear suspension but sliding the top of the rear shocks so they were more, or less, vertical? It's the same theory.

The more rake on a suspension unit the further the suspension will travel for the height of the bike to change by the same amount. Think of the vertical distance the bike travels & the ground as two sides of a right angle triangle. The suspension movement is the hypotenuse. Extend the length of the 'ground side' and the hypotenuse gets longer, meaning a change in the vertical height of the suspension requires a bigger change in the suspension travel.

So no the fork travel doesn't change, that's mechanically fixed by the design. But increasing the rake means the same amount of suspension travel covers less vertical height differences over bumps etc. Also because the suspension is moving further for a given change or ride height that should change the effective spring rate, the more rake meaning the stiffer the suspension if my logic is right. So if a vertical fork needs say 100lb to compress it 1". rake the fork by 45degrees & you'd need to compress the fork about 1.5" to drop the bike 1". So a 100lb load would now only drop the bike about 2/3"

Bored yet? It's too early for me to think like this, maybe I should spend more time just riding bikes? 

[Kiwifruit]

Hypotenuse..........Hooli is your real name Bamber Gascoigne ??

But well explained 

[Roo]

Hypotenuse..........Hooli is your real name Bamber Gascoigne ??

But well explained 

My head hurts  !  lol.

[Hooli]

Hypotenuse..........Hooli is your real name Bamber Gascoigne ??

But well explained 

I scared myself by spelling it right too! doubt I've had to do that since school. Glad it made sense though, I was trying to remember what I'd read about it as I wrote that.

Of course the few degrees difference we make to the rake means the difference is practically nothing and not worth worrying about.