Fork cartridge info wanted

Slightly off topic, but I was quite surprised to find that my SF2 has 35mm forks.

I thought they came out with 38's, but
- There is no sign of damage to the frame that might have necessitated a repair with the smaller parts.
- These 35's came set up for twin discs rather than drums.  (Does that mean that they are compatible with an earlier SFC?)

The cost of a 38mm Ceriani setup is prohibitive at this point, but I wonder if the 35's are in demand for restoration of earlier bikes.
If so, I might be able to offset the cost or do part exchange with someone.

Otherwise, I will be considering a fork brace to stiffen them up a bit.
 
Dale said:
Slightly off topic, but I was quite surprised to find that my SF2 has 35mm forks.

I thought they came out with 38's, but
- There is no sign of damage to the frame that might have necessitated a repair with the smaller parts.
- These 35's came set up for twin discs rather than drums.  (Does that mean that they are compatible with an earlier SFC?)

The cost of a 38mm Ceriani setup is prohibitive at this point, but I wonder if the 35's are in demand for restoration of earlier bikes.
If so, I might be able to offset the cost or do part exchange with someone.

Otherwise, I will be considering a fork brace to stiffen them up a bit.
Click to expand...


They're very likely original.
My SF2 also has 35 mm forks with a 35 mm bottom clamp and a 38 mm top with spacers.
Even at that relatively late time, there was no such thing as an catalogue Laverda but a case of what parts were to hand.
I very much doubt that you'll find an interest amongst Laverda owners for those forks; SFCs never had them, some very early disc triples did.

Out of interest, my SF2 carries the number 15832, what number is yours?

Ciao
Paul
 
Paul (or anyone);

Do you have any thoughts on the notion of a fork brace or, to get back onto topic, whether I can improve with more modern internals?
 
Dale said:
Paul (or anyone);

Do you have any thoughts on the notion of a fork brace or, to get back onto topic, whether I can improve with more modern internals?
Click to expand...


Dale,
15838. End of 74 I imagine. Yes, they slept together. Where you from?
As for a brace or modern internals, depends what you intend doing with the bike.
I've used mine for 20 years now, solo or two up with luggage, gentle touring or fast riding including coming down the Dolomites two up behind a local Italian. The rear frame loop broke on the bumps! I'm quite happy with the fork though you can feel it flex under very hard braking.

You can put a 38mm Marzo on there, more common than the Ceriani.

Ciao
Paul
 
Hauge said:
Yamaha trx have right side up forks with cartridge.
Click to expand...

??? Mine doesn't. Damping rod forks; yes they have adjusters for damping (rebound only I think) but are pretty ordinary. 41mm diameter is up on Cerianis or Marzocchis but I think there are better alternatives.

bazzee

Actually I lied. I installed cartridge emulators in the forks of my TRX. Sorry for misleading you!
 
My SF2 brought new in 74 also came fitted with 35mm forks. Would have to dig deep to find the number. Anyway they ended up pretty fucked up after coming into contact with some armco in Nth Queensland. So the bike ended up with a set of 38mm Cerianis.
 
This is all rather good news.

Paul:
I am doing whatever is possible to improve the bike' performance as an every day user, without killing its character.
Adding a brace is something that I would do if it had a big effect on the handling, but at the expense of adding weight.
If it is not a great difference, then I will not do it.

The bike will be used for pleasure riding and short commuting on bad roads.
I'd like to say long afternoon rides in the country, but I am limited to about 30minutes from one end of the island to the other.
Occasional tours.  (Sicilly is a good weekend jaunt from here).  I do want to make the pilgrimage to Breganze and Zane soon.
No racing, but I demand the best handling I can manage to achieve.

Steven
If the upgraded internals make as much difference as you say, then they will certainly be getting a shot.
I'll look at the link you have posted after work today, thanks.

Dale
 
For classic racing pre ?73 (here at least) max forks is 35mm unless you have proof that bigger was standard, so they are in demand amongst classic racers.
As far as handling goes, the top pre ?73 classic bikes here put in laptimes competitive with modern 600s, it is pretty sick.
They are also not allowed fork braces.
Better damping is a good investment but don?t worry about them being 35mm.
Lee
 
Anyone got some race experience with the 41mm Suzi 1100 ?89 Fork? I find the progressive Spring shitty, have to chance to a linear one anyway, but should I chance the Cartrige too?
 
Phil,
A bevel Ducati racer over here has been running this type of conversion for years but he just uses the whole stanchion instead of mating the internals etc. He reckons it's not too hard to make them fit and make them look original. He also runs top bushes sourced from a Kawasaki GPZ 900R from memory. I'll be doing the same to a set of Cerianis I'm about to use.

Keep us posted on where you end up.

Cheers
Morison
 
Hi Morison - are you saying there are 38mm stanchions off another make with adjustable cartridge internals - or that the Ceris can be bored out to 41mm to suit? - i've got marzos to do as well and wouldn't trust boring them out as I've have seen a couple break just below the oil seal holder area. - Regards - Phil
 
phil37 said:
Hi Morison - are you saying there are 38mm stanchions off another make with adjustable cartridge internals - or that the Ceris can be bored out to 41mm to suit? - i've got marzos to do as well and wouldn't trust boring them out as I've have seen a couple break just below the oil seal holder area. - Regards - Phil
Click to expand...

I want to hear about this!! I've go a pair of 38 Cerianis for the track bike, might be interested too.
 
Phil,

Apparently there are but I don't know which ones. This bloke reckons he's done both mods. He definitely told me he mates VTR cartridges into Cerianis for his race bike but he's also said he's run Jap fork legs with the standard internals. He was suggesting that they had cartridges but wouldn't say exactly.

What I have gathered from him was that I'm looking for US spec Yamaha and Kawasaki fork legs. I checked with a local suspension guy and he thought it might have been one of the mid sized Kwakas but wasn't sure. He also raised your question. Which is why they went to larger diameter fork legs in the first place. So they could actually fit cartridges inside. But then he said that he could install modified cartridges in my Cerianis but wouldn't say where they came from either. So this is where I stopped.

They might exist but I'm too far away from a wrecker to try and check. In the mean time I'm going to mate a set of Jap legs (with the standard internals) to my Cerianis. Jap suspension was heaps better than 70's Italian technology by the mid eighties so it's a start.

Cheers
Chris

Here's a list of some Jap bikes with 38mm forks which might help.

38MM Honda CR-125R (81-83)
38MM Honda XR-250R (84-85)
38MM Kawasaki KX-80R2/R3/R4/R5/R6/R7 (92-97)
38MM Kawasaki KX-125 A6-A7 (80-81)
38MM Kawasaki KDX-200 A1-A3 (83-85)
38MM Kawasaki KX-250 A5-A7 (79-81)
38MM Kawasaki KDX-400 A1-A2 (79-80)
38MM Kawasaki KX-420 A1-A2 (80-81)
38MM Kawasaki KL-600A1 "KLR" (84)
38MM Kawasaki ZX-600C1-C6 "Ninja" (88-93)
38MM Kawasaki ZX-600C7-C10 "Ninja 600R" (94-97)
38MM Kawasaki KL-650A1-A18 "KLR650" (87-04)
38MM Kawasaki VN-700A1 "Vulcan" (85)
38MM Kawasaki VN-750A2-A20 "Vulcan" (86-04)
38MM Kawasaki ZX-750F1-F4 "Ninja" (87-90)
38MM Kawasaki ZL-900A1/A2 "Eliminator" (85-86)
38MM Kawasaki ZX-900A1-A3 "Ninja" (84-86)
38MM Kawasaki KZ-1000C1-C4 "Police" (78-81)
38MM Kawasaki KZ-1000J1-J3 (81-83)
38MM Kawasaki KZ-1000K1/K2 "Ltd" (81-82)
38MM Kawasaki KZ-1000P1-P20 "Police" (82-01)
38MM Kawasaki ZL-1000A1 (87)
38MM Kawasaki KZ-1100A1-A3 (81-83)
38MM Kawasaki KZ-1100B1/B2 "GP" (81-82)
38MM Kawasaki KZ-1100D1/D2 "Spectre" (82-83)
38MM Kawasaki ZN-1100B1/B2 "Ltd" (84-85)
38MM Suzuki RM-125 N/T/X/Z (79-82)
38MM Suzuki RM-125 D (83)
38MM Suzuki PE-175 Z/D/E (82-84)
38MM Suzuki RM-250 N/T/X/Z (79-82)
38MM Suzuki RM-400N/T (79-80)
38MM Suzuki LS-650 FG/PG/FH/PH/PJ (86-8Cool
38MM Suzuki LS-650 PS/PT/PV/PW/PX/PY/PK1/PK2/PK3 "Savage" (95-03)
38MM Yamaha YZ-125 H/J/K (81-83)
38MM Yamaha IT-175 J (82)
38MM Yamaha IT-175 K (83)
38MM Yamaha IT-250 H/J (81-82)
38MM Yamaha YZ-250 D/E/F/G (77-80)
38MM Yamaha FZR-400 U/SUC/W/SWC (88-89)
38MM Yamaha FZR-400 A/SAC (90)
38MM Yamaha YZ-400 D/E/F (77-79)
38MM Yamaha IT-465 H (81)
38MM Yamaha IT-465 J (82)
38MM Yamaha YZ-465 G (80)
38MM Yamaha XT-550 J/K (82-83)
38MM Yamaha FZR-600 W/WC/AC/B/BC (89-91)
38MM Yamaha FZR-600 RA/RAC/RB/***/RD/RDC/RE/REC (90-93)
38MM Yamaha FZR-600 RF/RFC/RG/RGC/RH/RHC/RJ/RJC (94-97)
38MM Yamaha XJ-600 SD/SDC/SE/SEC/SF/SFC/SG/SGC "Seca II" (92-96)
38MM Yamaha XJ-600 SH/SHC/SJ/SJC "Seca II" (96-97)
38MM Yamaha FZX-700S/SC/T/TC (86-87)
38MM Yamaha XJ-700N/NC/S/SC "Maxim" (85-86)
38MM Yamaha XJ-700 XN/XNC/XS/XSC "Maxim" (85-86)
38MM Yamaha XV-700L/LC/N/NC "Virago" (84-85)
38MM Yamaha XV-700CS/CSC/CT/CTC "Virago" (86-87)
38MM Yamaha XV-700 J1/J1C (97)
38MM Yamaha XV-750 U/UC/W/WC/A/AC/B/BC "Virago" (88-91)
38MM Yamaha XV-750 D/DC/E/EC/F/FC/G/GC/H1/H1C/J1/J1C "Virago" (92-97)
38MM Yamaha XV-1000 L/LC/N/NC "Virago" (84-85)
38MM Yamaha XV-1100 S/SC/T/TC/U/UC "Virago" (86-8Cool
38MM Yamaha XV-1100 W/WC/A/AC/B/BC/D/DC/E/EC "Virago" (89-93)
38MM Yamaha XV-1100 F/FC/G/GC/H/HC/J/JC "Virago" (94-97)
 
Phil,

Did a bit more scratching and talked to few blokes.

One suspension builder told me he installed a set of cartridges in a bevel Ducati racer (different bloke to the first one I mentioned) and the rider wasn't convinced there was much of an improvement over standard. The rider complained there was a harshness that they couldn't tune out. He thought that the tight psychical dimensions of the 38mm tubes restricted the air flow too much and created a pressure imbalance which, he reckons, effects the valving. He thought this wasn't controllable unless you rigged up an external reservoir system. Too much money.

Another suspension guy reckoned the cartridge some are using is out of a Honda CB1100 Blackbird. He reckoned that this model Honda also has pretty crappy valving so he couldn't understand why they'd use the cartridge in the first place when he was always getting jobs to fix the standard valving.Too much money

All reckon you can't go past the simple Race-Tech emulator set-up when you compare bang for buck. I installed them on my Jota and I thought any improvement was pretty minimal. It worked but the front end was still pretty harsh. I used to run Ohlins front and back on a late model Guzzi I had a few years ago so maybe I was spoilt? With Ohlins you don't even notice the suspensions working it's that good.  

Cheers
 
Chris, those Race-Tech emulators are adjustable in a number of ways. You can make the forks more compliant by reducing the oil viscosity, backing off the valve spring pre-load (high speed damping), or by enlarging the bleed holes in the valve plate (low speed damping). It's a bit late now as you've got rid of your Jota, but they may simply have needed a bit of fine tuning.

Cheers,
Cam
 
There are or were 3 different springs available as well.There are different requirements for racing and fast street riding.Worked that out at the track invasion at Philip Island years back.It was an absolutely flawless surface,billiard table smooth and the racers were still complaining about the bumps.I would expect race quality suspending would require wheel control down to tiny movements.Zero interest in comfort,traction would be king.Back to the black arts again,or at least years of experience.I had a look at the shim wall of a local suspendion bloke.There were a lot of shims there to choise from.
 
Thanks Cammy, but I knew all that. I have to admit I'm being a pretty harsh critic here. I mucked about with mine three or four times changing the oil viscosity and adjusting the spring tension. The only thing I didn't do was drill out and/or add another bleed hole. It was bearable but so was standard.

I still think emulators are over rated to buggery because rod type dampning systems are limited. Sure the whole point of the emulator is to emulate a cartridge but there just isn't the range of rebound and compression adjustment you can get with cartridge shim stacks. The more research I do it's becoming pretty obvious that there's little possibility of making any quantum improvements due to the small size of the tubes. This kind of contradicts what I'm saying but there appears to be some evidence supporting using cartridges in 38mm forks. Which is why anyone who's racing, using Cerianis or Marzocchis, either works it out themselves or pays Maxton to do it for them.

Like I said, if you've ever ridden a bike with Ohlins suspension it spoils the shit out of you. It's the perfect compromise between comfort and being able to ride like a lunatic. The difference is absolutely qualitative and quantifiable.

If I'd kept the Laverda I'd be seriously considering using a set of wider BMW forks because there's heaps more options available. You see, with a bevel Ducati you don't have to worry about all of that suspension crap because they''re so well balanced and designed they already handle like they've got Ohlins........yuk yuk yuk :D

Cheers
Chris






 

Cheers
 
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