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tootler Profile
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Registered: 02-2012
Posts: 159
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gsxr400rr


hi all,i feel that my front forks on my 1998 gsxr 400 is a bit soft,how do i stiffen them up,this is only my second ever bike,the last one 30years ago,it was a gsx 250e,many thanks for any info,tootler
2/6/2012, 17:24 Link to this post Send Email to tootler   Send PM to tootler Blog
 
acidkiller Profile
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Registered: 08-2008
Posts: 195
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Re: gsxr400rr


is that a typo there is it 1988 or indeed 1998? not sure if there was a 1998 400. anyway if its either gk73a or gk76 its the same thing. first of all did u buy this bike or u have it for some time and decided u want it stiffer? because soft front can be compressed springs or low oil. the next thing you can check is the nut on top of the forks. its the one thats like and O but 2 cuts in the sides to fit a tool. thats used to stiffen or soften the forks. make sure u give the same turns on both forks.

if you just got the bike my guess is that you ll need new springs due to storage or bad use or an oil change. let us know the model of your bike as the 1988 is GK73A with standard forks and after 1990 is the GK76 with USD forks.
2/6/2012, 19:27 Link to this post Send Email to acidkiller   Send PM to acidkiller
 
garynortheast Profile
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Registered: 06-2005
Location: Mid Wales
Posts: 1679
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Re: gsxr400rr


To be honest the springs don't really deteriorate significantly. I would start by changing the fork oil. New oil alone will usually make a big difference, and if you put some 10 weight oil in it may well stiffen the front end up further. The other thing you could try would be to fit a set of progressive springs to the forks (if they don't already have a pair fitted - my 1986 GK71F has)

Another option would be to try fitting a pair of cartridge emulators in the forks. These improve the crude operation of the damper rods in the forks enormously. I have a set of these in the forks of my SV650s and they've made an amazing difference to the front end. Those particular ones are not the right size for your forks so you may have to do some research in that area first, but they are a cheap, and incredibly effective method of sorting the front suspension.
If you do go down the emulator route then you need to leave the linear fork springs in place as they don't work too well with progressive springs.

---
Gary.

2/6/2012, 20:07 Link to this post Send Email to garynortheast   Send PM to garynortheast MSN
 
acidkiller Profile
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Registered: 08-2008
Posts: 195
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Re: gsxr400rr


um gary i think u explained it in rocket science mode. he said its his second bike so i doubt he would have seen all those in the previous bike!
from personal experience i can say that springs deteriorate if left without oil for a few years and also depends on the rider. if the previous owner was a woman or someone with low weight the bike could have been set to his/her lighter weight which could be another reason to feel the springs softer. but it all comes down to checking the oil level and any leaks to start with.
3/6/2012, 0:52 Link to this post Send Email to acidkiller   Send PM to acidkiller
 
tootler Profile
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Re: gsxr400rr


thank you for replying,my bike is a gka76,its an import,registered 1998,it has upside down forks,i was talking to a fellow biker and he felt the front was very soft,i am not very mechanical minded,i will have to look at the forks again to see how to use your info,i keep my bike garaged but its at my joinery workshop a few miles from home,i must say this bike is totally amazing to ride,i will post a pic if i learn how to,just fitted new battlax 021 on the front,it matches the back tyre,the tyre fitter put 36 pressure in front,i think i read it should be 32 in one of your chats,again thanks for all your knowledge and experience guys,tootler
3/6/2012, 7:46 Link to this post Send Email to tootler   Send PM to tootler Blog
 
garynortheast Profile
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Registered: 06-2005
Location: Mid Wales
Posts: 1679
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Re: gsxr400rr


The trouble here AK is that the preload adjusters (the graduated knobs on top of the forks, if that is where they are located on USD forks) won't actually stiffen the front end. They are there in order to allow you to set the static sag. You can read more about it and about linear versus progressive wound springs here.

Put simply, linear wound springs have the coils spaced evenly along their length whereas progressive wound springs have a series of tighter coils at one end. This means that progressive springs become stiffer in effect the more they are compressed.

Sag is the amount that your suspension compresses under the weight of the bike (free sag) or under the combined weight of bike and rider (static sag).It's a 10 minute job to set the sag but you will need another pair of hands to help support the bike while you are sat on it. It's fully explained in the two links I've given you here.

Damping is the business of controlling the speed at which your suspension compresses and returns from a compressed state. It is done by forcing oil through restricted orifices in a tube (damper rod) on some bikes or through a valve on more sophisticated systems. Not sure which system the usd forks on the 76rr utilises.

If you are not familiar with the business of setting up your suspension then it is one of those things that is well worth spending a little time reading about. Well set up suspension can absolutely transform the handling of your bike, second only to getting some expert or advanced riding training.

---
Gary.

3/6/2012, 13:58 Link to this post Send Email to garynortheast   Send PM to garynortheast MSN
 
tootler Profile
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Registered: 02-2012
Posts: 159
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Re: gsxr400rr


thank you so much for for the suspension link,i have printed it off and will take it to the guy who will be servicing it for me,you definately are a wealth of information,these wee bikes are like hens teeth over here in n.ireland,i dont know anyone who has one/or had one,so all info is gratefully accepted,but i dont want to pester,i cant work out how to put a photo of my bike on to show itImage

Last edited by tootler, 3/6/2012, 17:26
3/6/2012, 17:22 Link to this post Send Email to tootler   Send PM to tootler Blog
 
garynortheast Profile
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Registered: 06-2005
Location: Mid Wales
Posts: 1679
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Re: gsxr400rr


Upload your picture to a picture hosting site like Photobucket. Once it's uploaded hover over the picture so that click on the menu appears, click on the image link to copy it, then paste it into the body of your post here.

Before you upload your picture to photobucket I'd recommend resizing it to about 800x600 pixels so that it doesn't take up a vast area in your post.

Good luck.

---
Gary.

3/6/2012, 18:00 Link to this post Send Email to garynortheast   Send PM to garynortheast MSN
 
tootler Profile
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Registered: 02-2012
Posts: 159
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Re: gsxr400rr


i have tried to upload from photobucket but must be doing something wrong,thanks for all info,can shorty levers be available for my bike or would the ones that fit a 98 srad do,dont seem to find many things for my import,would just like to change a few things,i dont carry passengers so would also like to have a single seat hump if thats what its called,thanks again, tootler
4/6/2012, 18:15 Link to this post Send Email to tootler   Send PM to tootler Blog
 
acidkiller Profile
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Registered: 08-2008
Posts: 195
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Re: gsxr400rr


i think they make shorty levers for the gk76 if not u can buy whole system from srads on cheapbay. single seat will have to be custom made i m afraid and i think they have some on cheapbay altho i saw them long time ago.
4/6/2012, 23:00 Link to this post Send Email to acidkiller   Send PM to acidkiller
 


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