What type of forks ?

[maxgain]

Hi there
found these forks on ebay, but I dont speak German. Does anyone recognise this type of fork. They look quite different to the ones on my Skorpion Sport. The caliper mounting holes seem much further apart. Any advice would be welcome.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320102378485&translate=yes#ebayphotohosting



regards - Stu

[Bill Jurgenson]

That fork was never used in any Skorpion model. That can be seen by at least two things:
- the small oil drain screw at the botton which none the Paioli forks that were used have;
- the wide (Yamaha typical) bolt spacing for the calipers.

My guess is a Yamaha FZ(R) fork used, in one of the very early prototypes.

Here with the air-cooled Rotax single:

http://f9g.yahoofs.com/groups/g_2819445/6510/__sr_/83da.jpg?grYcIJGBH_oWxe5s

here with the XTZ eingine:

http://f9g.yahoofs.com/groups/g_2819445/6510/__sr_/5b91.jpg?grYcIJGB3D06PMx.

Note that both still have the "glued-on" forged aluminum frame ends that were a feature of the Seymour-Powell design and aluminum swing arms.


The fork is probably also from Paioli since Paioli, like Oelins and Brembo, belongs to Yamaha. It is certainly usable, but you would need either to mill an adaptor for a modern caliper or buy a Yamaha caliper that fits.
A good excuse to throw the Grimeca shit away if you haven't already.

[maxgain]

Many thanks bill.
I had noticed the screws at the bottom and wide calliper mountings. Didnt know if it were from a cup. You replied to an earlier post of I wrote regarding mirrors. I was wondering what type of forks/front end setup you used on the Red Skorpion.

Perhaps you could suggest a good replacement set of forks that would fit straight into the existing yokes. Would I need to replace wheels/brakes and front mudguard.

Regards - Stu

[Bill Jurgenson]

If the tubes are 41mm, then the fork will fit. The question is, if the axle will fit.

The best replacement is the Kawa ZX600 fork complete with, calipers, wheel and rotors. The tubes are 41mm and it is a simple 1:1 change. I have one myself waiting to be used and friend of mine in Vienna used the complete set after an accident which bent his original fork.

Both my red Sport and my blue Tour have the original 41mm Paioli fork with Technoflex (Wilbers) progressive springs in the blue, WP in the red.

The racer has the 41mm Paioli USD from the SZR with Wilbers linear racing springs and changed shims. With enuf investment and diligence, the USD fork can be made to work well, but I do not recommend this change for normal oad use. THE OEM fork in the Skorpion is very good as it is, once the aftermarket progressive springs and different oil have been added.

Have I missed something? wshy do you want to change?

[maxgain]

Once again Bill thanks for your reply.
I am in the process of replacing the original worn rear shock and seized linkage/swingarm bearings. Just thought that I would update the front end. If the stock forks are pretty good anyway I shall look to replace springs and oil as you suggest.

Regards - Stu

[Bill Jurgenson]

Do not make the mistake to replace the rear unit with another Bilstein like the original. There are several alternatives, all much better and some of them cheaper as well.

The most obvious is of course to use a high-end made to order strut from Wilbers or WP. Altho this is by far the most expensive, it is also the best bet in the long run because such struts are completely rebuildable and work best. The WP OEM strut for the Replica can be had directly.

The red Sport has a Wilbers strut at the rear, Type 640, which was originally in the blue Tour. I bought it back in the 90ies when the Bilstein broke. Rebound and length adjustments.


The Tour, my "test bed," presently has an older fully adjustable Wilbers for an FZR with separate pressure chamber gotten used at eBay for maybe 150€. This fits 1:1 with no modifications and is slightly longer, raising the tail for better handling in the process. It is also adjustable in length.
Before I got that one, I modified the Sachs strut from the Aprilia RS250. Here is one:
http://cgi.ebay.de/Aprilia-RS-250-Sachs-Federbein-hinten_W0QQitemZ250105283323QQihZ015QQcategoryZ78421QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

This works very well with a different spring. THe WP spring for the Skorpion Replica can be had from WP and fits this strut perfectly. This is what I used. This strut has been used by several Skorpion riders. The modifications are not difficult, but it is not plug and play; some machining is necessary, both at the top and bottom. Once fitted, it is very good.

Then some OEM Yamaha struts fit directly. Obviously, the strut from the FZR:
http://cgi.ebay.de/Yamaha-FZR-1000-Federbein-mit-Umlenkung_W0QQitemZ150112837362QQihZ005QQcategoryZ49809QQrdZ1QQcmdZViewItem

Then the struts from the FZR600 fit as well, but the spring, here, is too weak.
http://cgi.ebay.de/FZR-600-Federbein-NEU-600-R-4JH-3HE_W0QQitemZ330111159972QQihZ014QQcategoryZ49809QQrdZ1QQcmdZViewItem

http://cgi.ebay.de/Federbein-FZR-600-R-4JH_W0QQitemZ140108726711QQihZ004QQcategoryZ49809QQrdZ1QQcmdZViewItem

These things are pretty good, better than the Bilstein at least, adjustable and a dime a dozen. Get any rauchy strut from the 1000er for a handshake and use that spring instead. A friend of mine has experimented a lot with various Yamaha struts. He is not on this forum, so ask for his email offlist.

My racer has a tailor-made Wilbers 641: out of the box-into the bike-perfect!


Just in case, I have the complete linkage in good condition here. And I also have that Sachs strut, modified, which can be bought from me or borrowed as a model for modifying another Sachs strut. At the moment, it is out of house for just that reason.

[Bill Jurgenson]

check out here:
http://search.ebay.co.uk/_W0QQsassZcreedxupQQhtZ-1

this guy has three fully adjustble FZR struts.
in the UK

[maxgain]

Great info Bill

I had searched through this forum and others to find what direct replacement shock I could use. Most riders seem to change for Wilbers,Penske or WP. I had no luck finding a second hand unit. Didnt realize FZR's would do the job.

Contacted WP as this was going to be my first choice based on reputation and locality. Unfortunately WP has stopped supplying shocks for the Skorpion, so I was a little disappointed. Managed to find a company over here that are main suppliers for Penske in the UK. They offer overall suspension services to the road or race rider. More importantly (to me anyway) they are very prompt in responding to my emails or phone calls. Here they are.

http://www.reactivesuspension.com/aboutUs.html


I have not got the unit yet as its custom made in the states. Hoping it should arrive in a couple of weeks. I am picking up the swingarm and linkage this afternoon. Managed to get the bearings out, but wanted them put in properly not just hit in with the largest hammer.

My fairings are being sprayed black again and original Skorpion decals put back on. All low-stressed bolts/screws are being replaced with stainless steel, nothing fundamental to the operation of the bike. Found a company over in Germany to get a new front race screen

http://www.gp500.de/

My aim is to restore the bike, but with a few small enhancements. I dont want to dramatically change its character. My next items will be front fork powder coat/ service and new exhaust. The original has an unsightly dent in the side from a friend reversing into the bike one day. He knocked it straight off the centre stand unfortunately. Probably looking at a M4 carbon fibre unit and maybe dynojetting the carbs, not to race spec.

Regards - Stu

[ZzerO]

[Bill Jurgenson]

re fzr strut:
the Wilbers unit for the FZR I have mounted certianly does fit 1:1 with no alterations. I'll try to take a picture today.

FZR600 3HE fits complete with linkage which is extactly that used on the MZ




and here is an Oelins which would fit. It is just like the Wilbers I have:



The seller listed it as from a FZR 750. Mine was from such a bike, too.

this one from an FZR1000 exup will obviously not fit:




Original length center-center is 305mm. a longer strut alleviates the need for shorter dogbones. THE unit I am using at the moment ( I experiment a lot) is 315mm long but also adjustable in length. I have the stock length dogbones.

Then, at the top, bolt diameters very betwen model years. I have seen none larger than the MZ and I use reduction bushings with a should in the MZ frame to reduce diameter to that of the strut. In the case of the RS250 Sachs, also to reduce inside width to fit the eye of the strut. No problem.

[Bill Jurgenson]

forgot:
in the racer, I use both shorter dogbones (Aluminum 128mm instead of the original 135) and a longer strut, adjustable in length and screwed out.
I have raised the entire bike 45mm to improve handling, obviously raising the tail more than the front but no where near as extreme as on the street bike in head angle. There I have the fork tubes standing 65mm proud and the tail lifted by the additional 10mm gained from the strut. With only a 130/70 rear tire, the thing is like a bicycle but it does need a steering damper. The racer does not need a steerng damper at all.

[ZzerO]

about the fzr shock.. there are some other models aswell. maybe they fit 1:1 but i was refering at the link you posted:

http://cgi.ebay.de/Yamaha-FZR-1000-Federbein-mit-Umlenkung_W0QQitemZ150112837362QQihZ005QQcategoryZ49809QQrdZ1QQcmdZViewItem

this shock is the one i have and here you have to grind a little away... for the hole, its also possible to mount bushings to eliminate the difference between shock and frame, its probably better too, but i had the grinding and drilling done in 1 time so this was easyier for me

i see that your bikes have a more extreme head angle then mine will have.. but could i lower the front f.e 10 mm in combination with the 2-3cm higher end?? or will this be to much. and don't you have problems with your chain??

greetz

[ZzerO]

and bill, you say you raised the entire bike, how did you raise the front???

[Bill Jurgenson]

here are the pics of the Wilbers sturt in my skorpion:

[img]http://f9g.yahoofs.com/groups/g_2819445/2e12/__sr_/fd7b.jpg?grAZoKGBhfadvn3Y[/img]

[img]http://f9g.yahoofs.com/groups/g_2819445/2e12/__sr_/a3b0.jpg?grAZoKGBCbvU9aRZ[/img]

the steering angle of my street bike is rather radical:

[img]http://f9g.yahoofs.com/groups/g_2819445/2e12/__sr_/f140.jpg?grAZoKGBTMGLgqVY[/img]


An yes, the chain protector on the swing arm is very short lived.

The racer has the Paioli 41mm USD fork from the SZR. USD forks cannot be moved very much up and down. They have to be clamped where the tube is machined for it. So, this one is not shoved thru at all. Since we made the triple tree in house, it was not hard to adjust the height further.
Lower tree has three clamping screws and is very wide.

[img]http://f9g.yahoofs.com/groups/g_2819445/2e12/__sr_/1c42.jpg?grAZoKGBZcSwJ6E5[/img]

so the front end is higher than the stock Skorpion. Obviously, the tail end is MUCH higher than a stock Skorpion, but the difference front to back is not as large as on the street bike.

[img]http://f9g.yahoofs.com/groups/g_2819445/2e12/__sr_/d4ae.jpg?grAZoKGB4ZPdzBTQ[/img]

Maybe one can see the difference in thse two photos.

As I said, the racer is 45mm higher and the seat itself another 40mm higher . It does nat have a cushion, so the actual difference is not as much. When the thing is on the starting machine, it is damned high to get on.My rear sets are not extreme at all, on the contrary:

[img]http://f9g.yahoofs.com/groups/g_2819445/2e12/__sr_/d0b5.jpg?groooKGB0ThIbXib[/img]

Rearsets MUST be under the center of gravity of the driver. There should not be any weight on the wrists when actually riding.

Another point, THe higher the bike (center of gravity), the less angle is necessary in corners and less hangoff as well.
simple geometry.

you speak of lowering the front another 10mm. form where? how high are the tubes above the triple tree?

[ZzerO]

hi bill

i'm sure you have tons of groundclearance on your race bike on my, stock, skorpion i have a bit of a problem with the groundclearance, my footpeg touches the ground in some corners, and at the left side, my exhaust

about the front lowering, it is comletely stock, so i guess its 30 mm above the yokes, the height of the clip ons...

i mounted the fzr 1000 shock today, it was a tight fit but it worked... it is higher then stock, not to high though cause i mounted slighty longer dogbones. but... the biggest, and strangest problem is, that it is still to soft. i dont understand that a shock for a 220kg weighing bike is still to soft for a 190 kg skorpion. i had the spring preload at the most stiff position, damping at max and it was still noticably weaker then the bilstein shock, so i mounted the bilstein back... bit dissapointed now...

so, or i'm gonna try to find a stiffer spring that fits the fzr shock(could get my hands on a spring from a ducati 900, wonder if it fits) or i'll have to find another solution...


ps, check your mail bill


greetz