Front Forks - Need advice.

[Tempest]

Its all about finding the right ballance tempest
You need to set the right amount of preload so the bike will stear properly but still have enough dip left to not bottome out. At the sametime you need to adust the the amount of rebound so the bike doesn't either go down too much and not return fast enough so you dont stick to the road when you brake or too little and it feels like a brick and doesn't stick to the road when you brake because it's boucing across ever little bump and ridge on the tarmac.

See, Simple

If only you could get right then move onto the next

Re the bottom out on the preload front, I guess we are just talking about under heavy breaking here?

May sound stupid, but going in a straight line, then break hard, is it obvious when the front end bottoms out?

Currently I have my settings on default/standard.

I did try harder settings (as advised on here) but my eyeballs felt like they were going to be jarred out of their sockets going down bumpy roads. Made the front end VERY hard. so I went back to standard. Not tried any softer yet.

The only thing I've really got to compare it against is my Yammie TDM850.

Tried a test yesterday, went down a road and round 2 corners. One corner at 60 and one further along at 70

On my TDM it felt quite fast and not sure how much faster I'd take it, but then went out of my Storm, and tried the same speeds. Deff not happy. I'd say the storm feels comfortable about 5 or 10mph less round corners than the TDM

It may be the riding position (TDM higher, so seems slower)
Poss wider bars, I dunno. the TDM just feels more planted on the road.

This is what I'd like to sort out.

[Stormin Ben]

May sound stupid, but going in a straight line, then break hard, is it obvious when the front end bottoms out?

Best thing to do is put a tie-wrap round the fork leg. Not too tight that it can't move but not too loose that it slips down when you let go
Then try the heavy braking test and see how close to the bottom of the lower yoke it is.

With preload you really only want to set it up the once and then pretty much leave it alone after that. There are a few 'how to's' if you use the search facility but if you can't find one I'll try and dig one out in a bit

Sorry if this sounds a bit dim!

The adjusters on the top of the fork legs...............

the large one (with the grooves round the outside) The preload adjuster, and the small inner screw, the rebound damper.

I guess the Preload just screws the spring down tighter, basically putting a load onto the spring so it's harder to squash down (harder ride)?

wheras the middle (rebound) slows down the unnit from springing back to full height be restricting oil flow?

Is this all correct?

YES

And could anyone summerise just how these 2 things affect handling?

Preload should be set so that under maximum force (hitting a big bump while braking hard) it has a 2-3mm of travel left
Any more and you're wasting movement
If your preload is too hard the bike cannot absorb the bump and yo feel it crashing through the bars instead

Rebound damping is the speed the spring bounces back from compressed and should be the fastest possible return under control

If it is too stiff then the forks will not have returned to normal before the next bump compresses them down again. This is called packing down

If it is too soft the spring bounces back up too quickly and can overextend causing the bike to run wide/ feel vague etc

Now the difficulty is in feeling if a harsh bump from the front is the forks not compressing properly (too much preload or compression damping too stiff) or if they are uncompressing violently due to not enough rebound

My advice would be to go along to that same bit of road, wind the rebound all the way out and ride it
Then wind it all the way in and ride it again
This way you will get a good feeling for what it feels lieka nd you can then judge if your original setting was too hard or too soft and adjust it to suit


Hope this helps to start with, keep the questions coming and we'll try our best to help you understand the zen like art of motorcylce suspension

[cupasoop]

Try this

http://www.gostar-racing.com/informatio ... set-up.htm

Or just search the tinterweb for suspension setup........loads of info out there

[Tempest]

Cheers for the info and the link.

I'm going to try the cable tie idea (great idea that) but just 1 thing I'm not sure of....

Errr, it says (after you gone out for a violent run of potholes and emergency braking!) your cable tie should be 10mm from the point where yout suspension bottoms out.

Only 1 query really. How do you know where it bottoms out?

I assume all bikes have difffering amount of fork leg (the shiny bit) showing at the point of bottoming out?

[Tempest]

Right then, cables ties in place, so about to go for a bumpy ride.
Will measure how much they've moved up when I get back.

[Tempest]

Ok, Job done, rode round over bumps, braked hard and even filled up with Petrol ;)
Only thing I did not do was deliberatly ride fast into speed humps!

According to the Cable ties (on both forks) the Forks have moved (maximum) about 77mm in total travel.

Not sure how close to bottoming out this 77mm is?

==== EDIT ====

Just noticed in my Honda Manual (which is the PDF File one, everyone probably has) which is the manual that goes with the later Firestorms as it says about the fuel gauge.....

Front Axle travel = 109mm
Front Fork travel = 120mm

Errrr, not sure why there are two values there, but if they are right for my EARLY firestorm (not the fuel gauge version) then I've got loads of travel to go yet!

I only mention the "other" version as I know at some stage Honda changed the forks a bit on later models.

Your Thoughts about my 77mm travel?

[Stormin Ben]

I take it that 77mm is from the bottom of the cable tie to the top of the fork seal when the front of the bike is up in the air ie the forks are fully uncompressed

How far from the bottom yoke is the cable tie?

It does sound like either the springs+spacer length is too long causing the front of the bike to sit too high (vague in corners and doesn't want to hold a line)
Or there is too much oil in them (harsh compression and forks lock up before they reach the end of their travel)

[Stormin Ben]

Tempest,
Only just seen your PM so I'll post the reply up on here so others can see it


Yep, releasing the fork tops in situe, one at a time should be fine.
They're not under a lot of pressure as standard (think the cap comes off an extra 10mm once you've wound the preload all the way out)

You can do both at once but bear in mind the front will collapse as soon as you release the second one so have a mate/ wife/ child ready to support it

With both tops off you can then remove the spacer and springs and measure the air gap (distance between the top of the forks and the surface of the oil)

Oil amount
This gap nees to be set to 130-140mm (with the springs removed and the forks fully compressed), but make sure it is not less than 130mm or the forks will lock before the end of their travel

Spring weight
0.85kg/mm spring if you weigh 90kg ot LESS
0.9kg/mm spring if you weigh betwee 90 -115kg
Ideally the combined free length of the SPRING + SPACER (without washers) should be 410mm.
Depending on the free length of the springs purchased you may have to shorten the spacer or make new spacers - ( it is only a piece of tube)

Don't be daunted by stripping the forks, once you've done it once you'll wonder why you were so concerned -there's really not much to it


cheers

Ben

[Tempest]

I take it that 77mm is from the bottom of the cable tie to the top of the fork seal when the front of the bike is up in the air ie the forks are fully uncompressed

How far from the bottom yoke is the cable tie?

It does sound like either the springs+spacer length is too long causing the front of the bike to sit too high (vague in corners and doesn't want to hold a line)
Or there is too much oil in them (harsh compression and forks lock up before they reach the end of their travel)

Ahhh, good point...... Did not think about that (front of bike in the air)
No, it's when the bikes just sitting on it's side stand.
Do I assume the forks will be compressed when the bikes just parked then?

Yes, it was taken from top of fork seal to bottom of cable tie.
Will do the yolk to tie measurement tomorrow (bedtime now!)

Still have not taken springs out to check.

If the bike is just parked on it's side stand, and I unscrew a fork cap, will it BOING out under major spring pressure?
and will I be able to get the thing back on again?

That's what I want to do, so I can check it's a standard spring.

[Stormin Ben]

One at a time, it won't be under major pressure

Just keep a downward pressure on the fork top as you unscrew it and it'll come away in your hand (ooh-err )
It won't take your hand off or break your wrist



As for measuring the suspension movement, if you have a willing helper you can pull the bike towards you on the side stand which will lift the forks in the air. (I use one hand on the top yoke and the other on the frame rail)
The helper can then measure the distance from the cable tie to the fork seal

NB you can also use this technique if you want to remove the second fork top at the same time to measure the oil level.

[Tempest]

Errr, well that was kinda a waste of time.

Back of bike on paddock stand, car jack under sump and just took the weight off the front wheel.

Undid fork top (had to use adjustable spanner as no socket that size)

Got it off eventually, hmmmm, now what.

Looked at manual, tried to suss out what next, shows a pic of a spanner on a nut I can't reach, screwed IN the preload to get more space, took washer out (the one with the gap cut out) the the fork cap still there.

Anyway, can't suss that out, so where they hell is the spring?
Shone torch down fork leg, jebus, all the way down there!!!

So gave up and put all back together

Could not work out how to get the fork cap (metal lump) off and out of the way.

And even if I did, no idea how I'd get to the spring?

Not quite as easy as I was expecting.

[thumper]

got me thinking this post has , my bike has never been adjusted i kinda just ride around the soft front end , though its a pain when the forks bottom out even on a wee pot hole or the likes , is there instructions or anything on here for dummies like my self that can tweek them to the hardest