Adjusting fork height without removing the front body cowling assembly
- Thread starter Flows
- Start date
I’ve done it on my Gen 1…. Ok I know you’re asking about the gen3 but hear me out.
Put the bike on a rear paddock stand and put a jack under the motor. . . then jack up the bike so the forks are topped out and no load on the front wheel.
Then look upward at the lower fork yoke and assess how much access to the pinch bolts on either side.. turn the steering until you have some clearance, enough to get a Allen socket or a cut down Allen key (if they’re Allen head bolts, not sure)
If you can loosen the lower yoke pinch bolts then loosen the upper yoke pinch bolts ( should be easier access to the bolt heads) and slowly lower the jack and load the front wheel a little.
You should be able to move the forks up through the yokes even without removing the front wheel, BUT… if you remove the front wheel it will make the fork raising a lot easier.
Give it a go, let us know how it goes.
Put the bike on a rear paddock stand and put a jack under the motor. . . then jack up the bike so the forks are topped out and no load on the front wheel.
Then look upward at the lower fork yoke and assess how much access to the pinch bolts on either side.. turn the steering until you have some clearance, enough to get a Allen socket or a cut down Allen key (if they’re Allen head bolts, not sure)
If you can loosen the lower yoke pinch bolts then loosen the upper yoke pinch bolts ( should be easier access to the bolt heads) and slowly lower the jack and load the front wheel a little.
You should be able to move the forks up through the yokes even without removing the front wheel, BUT… if you remove the front wheel it will make the fork raising a lot easier.
Give it a go, let us know how it goes.
Berlin Germany
Registered
& @Kiwi Rider
not yet at a gen3
but
at gen2
and gen1
this way
i guess / suppose that should work also at the gen3
because the gen3 fork is not a completely new development but is based on the gen2 (+ gen1) fork.
so check out this option of mine (by the link above).
_________________________________________________________________
if remember right ,
this job takes max. 1.5 hours plus some good tools (torque wrench)
+1 for lowering it,
but, he may actually be sliding them down a small amount, as he has been playing with suspension lately, and
it is ok if the top of the forks drop below the upper triple clamp.
Especially with a raised rear, it can be beneficial to really dial in the perfect rake and trail.
Spot on @sixpack577,
Due to my weight I have 10-15mm too much front sag with the current springs. Also the /55 rear has raised the rear by ~10mm. This took the rake and trail to a place where the turn in is fast but non linear. Yesterday I increased the rear sag from 27mm to 32mm (5mm or 8/10ths of a turn) and the bike felt probably the best it has so far but am now running out of ground clearance so will take the rear sag back to 27mm and lower the forks by 5mm.
All I have to do is remove the upper inner cowl to get to the lower fork clap bolts.
Due to my weight I have 10-15mm too much front sag with the current springs. Also the /55 rear has raised the rear by ~10mm. This took the rake and trail to a place where the turn in is fast but non linear. Yesterday I increased the rear sag from 27mm to 32mm (5mm or 8/10ths of a turn) and the bike felt probably the best it has so far but am now running out of ground clearance so will take the rear sag back to 27mm and lower the forks by 5mm.
All I have to do is remove the upper inner cowl to get to the lower fork clap bolts.
zeepopo2
Registered
Did you increase the rebound speed? That's probably what it making it felt non linear to you. With the increase in rear height, front is loaded much more. Which slows down the response after brake and turning. So always increase rebound speed after raising the rear. And by increase I mean open the screw 3 or 4 clicks. Adjust higher if needed.
Interesting comments as always Zee, do you mean if you raise the rear you should reduce the rebound on the front? I know you are a fan of loose rebound for many good reasons but isn't the rebound setting essentially tied to the spring rate and sprung / unsprung weight ratio? The spring rate increases with stroke especially in the last 30% due to the progressive air spring so if you are now spending more time at the bottom of the stroke would you not be better to increase rebound dampening slightly (given a linear rather than progressive or digressive rebound curve)?
The sensation of non linearity was more to do with geometry I think. Initial roll rate on turn in by bar pressure became slow / fast / slow rather than linear so it would roll, then fall, then settle. I haven't quite figured this out as yet but my sense is that it is tied to the relationship between rake and trail as determined by the head stock offset. The Gixer K5-6 is 23.45° 96mm and the Gen 3 Busa is 23° 90mm. With my geometry at 15mm rear raise from the 27mm rear sag, /55 tyre + 15mm too much front sag gives me a rake of ~21.84° with the 1480mm wheel base. Reducing this a bit by lowering the rear by 5mm removed most of the 'falling in' part of the roll in while still feeling really nice vs stock.
Add front rebound, as the front is more loaded by the taller rear, so more weight on the front, needing more rebound to perform the same as before.
Indeed, that is what I did. Will keep an eye on tyre wear for leading ridges. This issue with getting toward the end of the clickers is that it only controls bypass flow as opposed to mass flow and you end up with a digressive dampening curve (yellow line)
Same thing happens when you use thicker oil as the shim stack is a spring based mechanism rather then a flow based trim control so heavier oil distorts the slow speed as with cornering the clickers due to the squared relationship between fluid forces and velocities...
Looking forward to getting that 5mm ground clearance back but will wait until my neck lift front stand arrives.
Have also got some Ohlins lined up but confirming if the forks for the Gen 3 are actually in the March production cycle or just vapor-ware now that Ohlins is being sold... Might need to start thinking about fork mods instead which would be interesting.
Same thing happens when you use thicker oil as the shim stack is a spring based mechanism rather then a flow based trim control so heavier oil distorts the slow speed as with cornering the clickers due to the squared relationship between fluid forces and velocities...
Looking forward to getting that 5mm ground clearance back but will wait until my neck lift front stand arrives.
Have also got some Ohlins lined up but confirming if the forks for the Gen 3 are actually in the March production cycle or just vapor-ware now that Ohlins is being sold... Might need to start thinking about fork mods instead which would be interesting.
zeepopo2
Registered
Any time you are increasing load on a tire rebound should be faster ie opening the screw. Therefore spending less time at the bottom of the stroke and regaining a neutral chassis geometry quicker for more consistent transitions and balanced weight transfer. It's always a mess trying to explain settings. Some people say more some say less. I like to refer to rebound with fast/slow and compression soft/hard. Rebound settings are tied to load on the tire. Depending on your geometry a click harder on compression might also be in order In order to minimize the range of oscillation if you are going too deep in the stroke.
Aha, you are talking about the rebound to compression ratio when adding load without increasing spring rate. As I understand it with a 0.7 - 0.75 rebound zeta an R:C of 0.8:1.0 is a baseline rule of thumb ratio for low speed then diverging further where spring rate is sub optimal to prevent packing.
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I'de say that you're consistently very good at explaining suspension, and making it understandable even for those not familiar, from stock, to fine tuning the aftermarket.
I always appreciate your input, and have learned more about fork shims from them over the years than anywhere else.
@Flows you do too much math...you're making my head hurt...
lmao
You guys keep it coming.
I'm pretty decent at setting up suspension, but there's always alot to learn
zeepopo2
Registered
Much appreciated! Glad I can help!
zeepopo2
Registered
Ohlins being sold? Damn
zeepopo2
Registered
That right. There is a ratio that creates a optimal setup. Many will get you into a neutral setup but the Hayabusa is too fat. Gotta go into a higher ratio since the front is loaded with a much higher weight than a standard superbike. At a certain point compression is more about limiting the range of rebound movement more than anything else, as long as you don't get tire chatter you still have space for a harder compression to balance rebound. Control the back and forth Weight transfers thru preload not compression. In my opinion a Hayabusa should be in the 150%+ speed rebound from stock.
I see you looking at restackor lol. That's a deep rabbit hole. Just gotta open up the forks and measure everything. Its a great learning tool, just their articles are very informative. I'm going Penske Gas fronts this year so I'll leave it to them to measure my new setup.
jcornwell101
Registered
I have adjusted fork height without taking the front end off the bike. I would loosen the bottom pinch bolts and crack open the top ones. If I needed to go up I would hit the bottom of the fork near the axle pinch bolt with a dead blow and measure each side with a caliper. If I needed to go down I would just hit the top of the fork cap avoiding the preload and rebound adjusters. Once the top measured even I would torque the top pinch bolts. Then I would press the front brake forcing the suspension to compress a few times then letting it settle on its own. Then I tightened the 2 other pinch bolts on the bottom triple clamp.
I never had an issue doing it this way or damaged anything.
I never had an issue doing it this way or damaged anything.
Chuckles, here is said rabbit hole Zee is referring too.. ReStackor Suspension Response
Like it! Thanks, guess with that Slacker tool I have been fiddling with I can verify the front end stiction hasn't increased and might also mark just below the bottom clamps and measure from there due to the Gen 3s bar clamps.
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