new fork springs

Well Ive just ordered new fork springs for both my bandit and the wifes GSX650F
Went with the racetech springs and using their online calculator worked out what I needed.
Ordered the parts from Solomotoparts and gota say very easy to deal with.
They didn't have what I was after so sent em an e-mail inquiring if they could give me a price and they put what i wanted on their list.
Total with the springs and a RK chain tool ended up being ~$400 aud shipped to my door which was cheeper than springs only locally

So the front ends will be coming apart (again) shortly and getting all new springs and oil. I may end up using 7.5w or 10w oil, I haven't decided yet.

I'll let you know how things go

i find the front is a bit 'bashy' unless i am going soft - it will be interesting to see how the new springs go. i see they are about 100 bucks - i thought they would have been more expensive. where was the calculator to work out what rate? i might have a look.

Here's the spring calculator. The Holeshot springs are 1.1kg/mm and this is a little on the firm side for Aussie roads, but just great for the track (or judging by your avatar might be under sprung! ). Stock damping will be an issue as it will have too much compression damping (which is the bashiness) and too little rebound for these spring rates, (I think stock is about 0.7kg/mm).

Cheers

I'm going to do the springs first with new oil and see how things are.

Using the calculator with the default weight for the bike is not quite correct. 471lb works out to 213kgs and the bike is not that light.
I sent racetech an e-mail asking them to explain what they meant by semi wet weight so I was sure, and it is the total weight of the bike (ride away) less a full tank, so using suzuki's figures it will be 234kgs. Not a huge difference but enough to push it up to the next spring for my fat arse. Even if I loose the weight I want to I will still be just below needing 1.1kg springs according to their calculator.

After I changed the fork oil to 7.5w motul fork oil I found a good difference in damping so I may not have to change valves yet, only time will tell I guess.

From my researching I have found that the standard fork oil can be anywhere from a 5w to a 10w due to allowable tolerance used (the + or - thing).
According to charts I've got, the SS08 oil as speced in the service manual (when spot on the money) is actually above the motul 7.5w in terms of viscosity.which makes sense as my bandit no longer has the "bashiness" as bad when going over sharp bumps.
I'll probably use 7.5w in both bikes as the G10 as speced for the GSX650F is about on par with the SS08 so may give the same results when I change.

We have an ex racer with a new shop here and this is one topic I wanted to discuss with him along with braided lines and new pads on the front. Love the B1250 but hate the front dive and after seeing about 120mm used in my videos its enough for me to do something about it.

Hi Damien, yes I would guess that 7.5 is about the best compromise that you are going to get. I found 5wt to work well with the standard springs but it would be insufficient with the heavier springs.

Cheers Peter

do you know if you can change the oil without removing the forks

potatomasher wrote:do you know if you can change the oil without removing the forks

I think you can, just loosen the top pinch bolts, remove the caps then pick the whole bike up and turn it upside down.

Um I don't think so, but if its anything like mine, it not that big a deal to remove them.

well thats inconvenient - on the CB750 i had some time ago there was a bleed screw on the bottom of each fork and you just took it out and the oil ran out [actually not that its got anything to do with forks, but they also had a screw in the centre of the counterhshaft sprocket which you could adjust to let sump oil slowly leech out and spread from the sprocket onto the chain. this actually was a top idea and you never had to oil the chain by hand]

Again if it's anything like mine you need to adjust the oil level with the spring removed, so letting out the plug doesn't help much, I'm sure there are others that know the specifics of your model.

on the 1250 it is best to pull the forks out to get all the oil out of them.
Apart from taking the wheel and brake calipers off, I recon if you have a S model, taking the whole fairing off the bike makes it a bit easier for removing and installing the fork legs. Takes about 10 mins to do.
*Take the gauges off
*undo one plug behind the gauges and thread it out of the fairing braket (there is no need to undo the indicator or headlight connectors)
*remove the 2 screws at the side of the fairing near the tank
*remove the two bolts that hold the fairing braket onto the frame
*take the hole fairing off the bike and put in on a towel on the floor, jobs done

After tipping them upside down (after getting the spring out etc) you also have to pump (stroke) them to get all the oil out.
I found that pumping the fork and leaving it for about 15 mins got heaps more out than just draining.

You will need some kind of tool to hold the damper rod end so it doesn't disappear. from memory it can sink below the level of the fork tube which can make it harder at assembly time. I used a old hollow mop handle with a plastic end cap, drilled a hole in the plastic end cap and tightened it onto the damper rod. The special tool only needs to be about a foot long.

You need to fill the fork tube without the spring fitted. Bleeding is probably the most pain in the arse bit of it all I recon.

If you're interested I'll take some pics and do a how to thingo when I get around to doing them. Probably in about 2 weeks

Dekenai wrote:I think stock is about 0.7kg/mm

Not sure what the 1250 bandit ones are but they appear to be progressive springs.

Racetech recon the standard GSX650F are 0.78kg springs and this matches with other info I have found around the traps.

Yes the 1250 springs are progressive, don't know where I got the rate from, had a feeling it was from Racetech,

Cheers

Parts arrived yesterday arvo. :-)
Getting wife to get some fork oil tomorrow. I've decided to stick with 7.5w motul oil and see how it goes.
I'm guna do the wifes GSX650F this weekend so I'll do a "how to" with some pics if you like. I'm also going to be doing the headstem bearings at the same time (clean, grease and adjust, not replace)

I'm also guna look into some theories about TB balance I have to see if they turn out for the better or not on the bandit but if it all works out I'll post another thread on that one

Eagerly awaiting your post on how the 650 goes with new springs and oil Dhula.
BTW I got a quote from a bike suspension specialist over here for 1kg springs and "gold valve" emulators removed and replaced - ride in and ride out $650AU for my 650. Wow that's $1 per cc

EDIT: I have removed the bit about taking off the fairing as I think it was a bit out of context seeing how I didn't get any more pics

So starting from this


Next thing is to take off the front wheel. I didn't take pics of this bit as the user manual shoes you how.
Also take this bolt out as it holds the brake hose.


Once the wheel is off, take the front guard off


Take note that there is an arrow on the mounting plate behind the guard that the screws screw into. The arrow points forward when reassembling it all.

Next is to remove the fork from the bike. Before doing the next steps, undo the top cap slightly (just enough to loosen it, no more. Tightened to 23Nm on reassembly) as once the fork is off the bike, unless you have a special tool to hold the upper tube, you wont get it undone easily. You can also set the preload to it's softest at the same time

Tightened to 23Nm on reassembly

Tightened to 23Nm on reassembly

To end up looking like this


Stay tuned as I'll update shortly

I pulled my forks out today to take to Frank Pons to get him to fit heavier springs (Race Tech, .95/kg and revalve them.
It was a ten minute job to pull the forks out without taking the fairing off of my 1250S model, might be a bit harder to get at the bottom triple clamps on the full faired version, but i have done it before on other fully faired bikes and its not a drama.

I was unaware that the 1250 had catridge forks, i thought they would have been dampner rods on a budget priced bike.

The front end is now very smooth, very compliant and turns in nicer after the fork job. I also pushed the forks thru 5mm to help turn in. Most impressed and worthwile investment.

Yeah, its amazing how decent suspension can both ride and handle better, if you haven't already done so, a Holeshot forkbrace will make it work even better.

Cheers

Dekenai wrote:Yeah, its amazing how decent suspension can both ride and handle better, if you haven't already done so, a Holeshot forkbrace will make it work even better.

Cheers

Fitted a brace awhile ago, certainley makes a difference.

stretch wrote:
Fitted a brace awhile ago, certainley makes a difference.

Whats involved in fitting the brace?

If you are OK with destroying the rubber fork leg stone guards then you don't have to do any disassembly, otherwise its drop the fork legs and slip the guards off then install the brace and then re-assemble. Very straight forward.

Cheers Peter

Well I've finished the job on the wifes GSX650F but unfortunately I don't have any more pics to post about it. Took em, then the boys got the camera and deleted them to make room for their own photo taking efforts.

Stretch. You're right, you don't have to remove the fairing to get at the fork legs, I did it because I was using the time to also do some work in behind the fairings and seeing how it takes all of about 10 mins to remove the front part I thought, why not.

I've only taken the bike on my normal work commute, but the difference is huge.
No more bottoming out over bumps, no more "bashyness" over smaller ones, far less dive under brakes, less rocking when hard on it thru the gears.
The bike feels much smoother to ride, turn and is generally much (much) better.
the springs in the 650 are 0.95kg/mm suited to my wife so not the best for me and my fat arse, but they make a huge difference.
I used 7.5w motul fork oil with no changes to the valving (only changed the springs) and initial thoughts are that it could be a bit underdamped, but it's not too bad. 10w might be better with the original valving but I'll leave it as is until we get out on a longer ride. I may decide to go with new valving yet, but that will depend on $$$$ in the short term.

Well the mrs has taken the 650 for a spin and in her words
"the difference is frigging amazing"

She set off on a 15 min spin around the block to see how she felt and give me some feedback so I could plan if I needed to change anything.

2 1/2 hours and 200 odd kms later she arrived back at the house so things must be much improved.

The tax man has blessed me with a few dollars today so after getting some almost overdue new tyres for the prado, I may just bite the bullet and get the valves for both bikes and go the whole hog.

Can you post up a "shopping list" of what you need to buy to do this modification? (seals, bushes etc etc)
Any special tools you found helpful?
Cheers!!

To do just the springs, you will need normal tools. The only special tools you'll need are (if you can call them special)
A measuring jug (little tip, don't put fork oil in your mrs good pyrex one, she don't like it)
A torque wrench that will do down to 23Nm and up to 100Nm (I have a 1/4 drive one for the small stuff and a 1/2 drive one for the bigger stuff.
A pipe cutter to cut the new spacer tube to length.
You could also get yourself a proper fork oil level syringe or make something using a 50ml syringe to do the job like I have done.

Then all you'll need is the springs, some fork oil and somewhere clean to do the job.

To do the valves you'll need a few more things. Do you want to go that far, if so I can post up more info.

well not being mechanically adept i am taking mine to terry hays in a couple of weeks to get new springs and valves in the front - so should be interesting to see what the difference is.