Soggy FZR600 forks

[kerryg]

My 1989 FZR600 has a pretty crude front suspension. No adjustment possible and it is very soft (I can nearly bottom the forks by pushing down hard on the bars). I've done a bit of research and apparently the factory springs are rated at only 0.464kg/mm while Race Tech's $300 springs for the same bike come at 0.89kg/mm for my (not inconsiderable) weight. I'm a bit reluctant to fork out $300 on such an old bike so has anyone got any advice about modifying the existing forks? I could put heavier fork oil in (standard is 10 weight, so could go to 15 or 20) and I could put a spacer in to increase the pre-load, and even shorten the factory spring (my research indicates a shorter spring is a stiffer spring) BUT will this give me the result I need? I don't want something completely "wooden" or a pogo stick result at the front any more than the current marshmallow situation, and I wonder whether anyone has any experience of this kind of exercise?

[James Deuce]

My 1989 FZR600 has a pretty crude front suspension. No adjustment possible and it is very soft (I can nearly bottom the forks by pushing down hard on the bars). I've done a bit of research and apparently the factory springs are rated at only 0.464kg/mm while Race Tech's $300 springs for the same bike come at 0.89kg/mm for my (not inconsiderable) weight. I'm a bit reluctant to fork out $300 on such an old bike so has anyone got any advice about modifying the existing forks? I could put heavier fork oil in (standard is 10 weight, so could go to 15 or 20) and I could put a spacer in to increase the pre-load, and even shorten the factory spring (my research indicates a shorter spring is a stiffer spring) BUT will this give me the result I need? I don't want something completely "wooden" or a pogo stick result at the front any more than the current marshmallow situation, and I wonder whether anyone has any experience of this kind of exercise?

Preload doesn't stiffen your springs it just starts suspension travel further up or down the range according to the adjustment you make. Heavier fork oil adjusts the damper rate on how quickly the oil flows through various damper holes. The new springs, combined with heavier fork oil would get the result you are after. My TRX suffered from soft, harsh suspension and the Racetech fork springs have made a HUGE difference. It is well worth it in my opinion, and you wouldn't know yourself once you've done it, even on such an "old" bike.

[kerryg]

The new springs, combined with heavier fork oil would get the result you are after. .

Thanks for the reply, Jackrat. What weight oil did you go to?

[James Deuce]

Thanks for the reply, Jackrat. What weight oil did you go to?

Me Jim2, me not Jackrat.

I went for 15 wt in the end.

[riffer]

Here's another idea.

The FZR600 will accept the FZR750 or FZR1000 front end. You need the forks, triples, and clip-ons. You can take everything from the 87 model through till they went USD, I think in 93.

Reason you need new clip-ons is that the FZR is about 39mm tubes. The 87-88 models are 41mm, and its 43 from 89 on.

Of course, you need to be able to find some. Try Aussie. There aren't any in New Zealand. I know, I've tried.

My bike runs a full FZR1000 front end. Quite firm, especially with 20wt oil in it.

What you might want to try is the springs out of some FZR1000 forks. Try the wreckers. There are a few crashed FZR1000's around with rooted forks, but the springs are still quite usable. That may work too.

[wkid_one]

Mate - Call Suspension Tech in Ellerslie ( http://www.suspensiontech.com/ and ask him what he thinks. He did the front end of the VTR and it made a wicked improvement to the bike - esp given the VTR is similar to the FZR with hellishly undersprung forks (VTR spring rate is ideal for someone weighing 56kg according to Race Tech's man and website).

I would go with new springs. Anything you do to the front end of the FZR like changing oil, spacing for preload etc is only going to minimise the problem and is never going to erradicate (like that word?) it. Adjusting preload won't help bottoming out, and changing fork oil won't either.

Go for the new springs. Try sourcing them from different places or buying OS yourself - and then I dare say you will be able to find someone on here to help you fit them if you can't yourself.

$300 is a small investment in the handling of the bike.

Either than - or buy a new one.

[geoffm]

Fizzer forks are pretty budget.
Cheep fix is 12.5wt (50% 10wt and 50% 15) or play around to suit (you may need 15 if you are porky), and reduce the airgap. Off the top of my head I can't remember the airgap in the fors we ran in the 400. Don't go to overboard, as you will lock up the forks

Increasing the oil weight increases the compression (and rebound) damping, and you may find the forks become harsh adn don't react to a series of bumps - just skips off the top if you go to heavy.
The airgap acts as a rising rate spring, and reducing this increases the effective spring rate. Again, don't go silly otherwise you may as well weld the top and bottom together, and you will pop the fork seals (always weak on these anyway).
For a guess, reduce the airgap by 20mm and try it.
What is the static sag - adjust this with the preload spacers.
Geoff

[kerryg]

Me Jim2, me not Jackrat.

I went for 15 wt in the end.

Sorry about the name mix-up Jim and thanks for the info

[kerryg]

Fizzer forks are pretty budget.
Cheep fix is 12.5wt (50% 10wt and 50% 15) or play around to suit (you may need 15 if you are porky), and reduce the airgap. Off the top of my head I can't remember the airgap in the fors we ran in the 400. Don't go to overboard, as you will lock up the forks



Well thanks Geoff I think :Oi:

[kerryg]

Go for the new springs. Try sourcing them from different places or buying OS yourself - and then I dare say you will be able to find someone on here to help you fit them if you can't yourself.




$300 is a small investment in the handling of the bike.

Either than - or buy a new one.


Yes I think I will, and thanks for info. I'll see what I can pick up on EBay. Even retail in the USA they're under USD100 so why you have to pay NZD300 (just under USD200) in NZ beats me

[riffer]

Yes I think I will, and thanks for info. I'll see what I can pick up on EBay. Even retail in the USA they're under USD100 so why you have to pay NZD300 (just under USD200) in NZ beats me
Shipping costs. They are horrendous...

[wkid_one]

Shipping costs. They are horrendous...No man - get it from the UK as the shipping costs are HEAPS betta. I don't buy out of the States as the price of the goods are great - but the shipping can often be more than the goods.

Last time I paid five pound postage to NZ and it arrived in 2 weeks. Total purchase price was only $70NZ - it was quite heavy too as it was footpegs and titanium sliders.

Try these sites for springs

http://www.mandp.co.uk/homepage.aspx?cmd=product&arg=527245
They have Hagon, Progressive and Ohlins Springs
Progressive Springs are UK$59(So NZ $140ish)

http://www.racinglines.co.uk/html/suspension.html

http://www.biketorqueracing.co.uk/Handling/forksprings.asp
About UK$72 per pair

http://www.hagon-shocks.co.uk/Fork_Springs.htm
<TABLE borderColor=#000000 width="100%" bgColor=#00ffff border=3><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD class=xl24 style="HEIGHT: 12.75pt" height=17>FZR600 GENESIS</TD><TD class=xl24 align=middle>88-93</TD><TD class=xl24 align=middle>500-065-04</TD><TD class=xl24 align=middle x:num>10</TD><TD class=xl24 align=middle x:num>150</TD></TR></TBODY></TABLE>

That is the part number, recommended SAE and Air Gap (in mm, fully compressed, springs not fitted)

More links if you need them - go to this site......

http://www.bikersweb.co.uk/directory/parts__accessories.htm lists all the bike shops in the UK

[FROSTY]

I had an 89 fzr600 and had the same problem. I spent ages stuffing around and finally bit the bullet and bought a set of Progressive brand fork springs.
I used 15w oil and used 20cc more oil than factory reccomended.
It totally transformed the front end of the bike.
The progressive springs were from memory like $150 nz
Oh and I wnt down the path of spring spacers and it was a total waste of time.
Dang ya gotta love log books . :baby:

[kerryg]

I had an 89 fzr600 and had the same problem. I spent ages stuffing around and finally bit the bullet and bought a set of Progressive brand fork springs.
I used 15w oil and used 20cc more oil than factory reccomended.
It totally transformed the front end of the bike.
The progressive springs were from memory like $150 nz
Oh and I wnt down the path of spring spacers and it was a total waste of time.
Dang ya gotta love log books . :baby:


Thanks Frosty that's helpful.

[kerryg]

Try these sites for springs



Thanks a lot! This forum is great!!

[wkid_one]

Welcome - glad I could help - it filled in 20 minutes of my boring stay at home and recuperate day

[Milky]

cant you get them re-tempered too? AFAIK that is a simple matter of heating them up to a certain temp, then recooling them in a stretched out position....

[kerryg]

cant you get them re-tempered too? AFAIK that is a simple matter of heating them up to a certain temp, then recooling them in a stretched out position....


Thanks for the idea. Actually I rang a couple of spring places thinking I could get springs made locally but didn't get very far (actually got nowhere). I rang Snells who said they don't do that kind of work (start at 8mm diameter wire believe it or not) and recommended I talk to another outfit (Curtis Springs) who said they only do very small springs and advised me to talk to Snells...at which point I pulled out the one remaining hair on my head and gave up. If anyone can suggest a spring maker who can either make or re-temper fork springs I'd be most interested to know for future reference

Meanwhile I think I've found some Progressive springs at a good price...will know later today

[wkid_one]

Call Suspension Tech - they may be able to refer you on to someone.

Otherwise try someone like Chris at Haldanes or the Bike Shops - they may point you towards someone as well.

If you know the specs of the springs - try Superior Springs in Wellington - 04 9392100.

<TABLE height=532 cellSpacing=0 cellPadding=0 width=646 align=center border=0 cool gridx="200" usegridx gridy="200" usegridy><TBODY><TR height=1 cntrlrow><TD width=1 height=1></TD><TD width=645 height=1><SPACER height="1" width="636" type="block"></TD></TR><TR height=529><TD width=1 height=529><SPACER height="529" width="1" type="block"></TD><TD vAlign=top align=left width=645 height=529 xpos="0">http://superior.co.nz/images/images/compressionspring.gif</TD></TR></TBODY></TABLE>

Also - you could try CMI Springs in Auckland, 09 579 4089

[Milky]

Thanks for the idea. Actually I rang a couple of spring places thinking I could get springs made locally but didn't get very far (actually got nowhere). I rang Snells who said they don't do that kind of work (start at 8mm diameter wire believe it or not) and recommended I talk to another outfit (Curtis Springs) who said they only do very small springs and advised me to talk to Snells...at which point I pulled out the one remaining hair on my head and gave up. If anyone can suggest a spring maker who can either make or re-temper fork springs I'd be most interested to know for future reference

Meanwhile I think I've found some Progressive springs at a good price...will know later today
The one i can see advetising heat treatment in the yellow pages is superior springs - http://www.superior.co.nz .. i think wikd pointed that out already though. Dad says there used to be a bunch of guys called Gerrard Springs?? in Great South Road - near Church st intersection - who used to do the job... I cant find them in the directories, so maybe they have merged or gone out of business :(

[kerryg]

The one i can see advetising heat treatment in the yellow pages is superior springs - http://www.superior.co.nz .. i think wikd pointed that out already though. Dad says there used to be a bunch of guys called Gerrard Springs?? in Great South Road - near Church st intersection - who used to do the job... I cant find them in the directories, so maybe they have merged or gone out of business :(

Thanks Milky I'll file that info away for future reference. 'Cos it's all a bit complicated and outside my very limited tyechnical knowledge, (look at the Superior Springs form Wikid supplied!) and because it's such a critical aspect of the bike I'm a bit nervous about local manufacture or re-working so I've bitten the bullet and ordered some springs. Progressives are 6 weeks to get here and can't wait that long so.....I've bitten the bullet and ordered the Race Techs. Oh well, it's only money.... :(

[F5 Dave]

I’ve been away so missed this one, sorry if it's a bit late.

I’ve had springs made but you have to be a bit careful what you ask for. A friend (no not me!) who got some fork springs made up but they didn’t fit as the diameter was too big to fit in the tube. Poos.

Yam forks are always too soft for some reason & you will enjoy the difference. I’ve shortened a few springs over the years (RZ350 KDX200 etc) with good results.

I learnt the idea & technique from an old dirtbike mag. Recently I’ve found the article on the web, about 6 down from the top. It’s a good site so I may have to post it separately as well.

Click here (http://www.off-road.com/dirtbike/tech/)

[kerryg]

I’ve been away so missed this one, sorry if it's a bit late.

I’ve had springs made but you have to be a bit careful what you ask for. A friend (no not me!) who got some fork springs made up but they didn’t fit as the diameter was too big to fit in the tube. Poos.

Yam forks are always too soft for some reason & you will enjoy the difference. I’ve shortened a few springs over the years (RZ350 KDX200 etc) with good results.

I learnt the idea & technique from an old dirtbike mag. Recently I’ve found the article on the web, about 6 down from the top. It’s a good site so I may have to post it separately as well.

Click here (http://www.off-road.com/dirtbike/tech/)Hi DAve and thanks for good info and the link (interesting stuff). I've fitted my Race Tech springs now so problem is hopefully solved for the FZR600 .