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1Back to top Go down   Wirth springs in 4V forks Empty Wirth springs in 4V forks on Fri Jun 22, 2018 10:05 am

duck

duck
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Anybody ever put Wirth springs in 4V forks?

I have two questions:

1) Spacer length - the Wirth springs are considerably longer than the stock springs. Do I need to cut down or get rid of the stock spacer?

2) The pre 8/91 forks have a short spacer doodad (BMW "Pad" 31422310153) at the bottom of the spring. The Wirth springs have a smaller inside diameter so the pad doesn't fit in the bottom of the Wirth springs. Leave it out?


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

2Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Fri Jun 22, 2018 4:05 pm

nino

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I mounted Wirth springs in K 100 8 V. Simply removed plastic spacers from tubes and push new springs inside. That simple change completely transformed bike. Better stiring and much better braking.

Dont know about 16 V bike but Wirth was best improvement on my 8 V bike ever.
Regards

    

3Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 3:10 am

duck

duck
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Update: The instructions that came with the springs are in German but I found a PDF in English here:

http://www.wirth-federn.de/gridfs/file/5681215e7775821bb78d3ebe

That says to not use the old spacers.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

4Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 3:14 am

duck

duck
Life time member
Life time member
@nino wrote:I mounted Wirth springs in K 100 8 V. Simply removed plastic spacers from tubes and push new springs inside. That simple change completely transformed bike. Better stiring and much better braking.

Dont know about 16 V bike but Wirth was best improvement on my 8 V bike ever.
Regards

The instructions I found said to switch from 10 weight fork oil to 15. Are you using 10 or 15 with the Wirth springs?

Since the factory springs in the 4V forks are progressive it probably won't make as big a difference as on a 2V K100 but will most likely still be an improvement.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

5Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 10:29 am

nino

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i didnt find any oil choice for Wirth, so i put ATF which is 7,5 probably. Anyhow Wirth are progressive, dont bother with oil type. If you want firmer put 15 W, but 7,5 was enough.
Totaly different feeling

    

6Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 11:12 am

duck

duck
Life time member
Life time member
I have 10W on hand and since I'm putting K1 forks on a K75 I probably don't need firmer. The Wirth instructions say that 15 gives somewhat better damping.

Thanks for your input.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

7Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 12:42 pm

Two Wheels Better

Two Wheels Better
Moderator
Moderator
In the Marzocchi forks on my Big Block I chose to use PJ1 7.5W, and it works a charm; supple and responsive to ripples as well as larger bumps and dips, but with a planted feeling. I would guess 10W would be more suited to a stock (heavier) bike as 15W might be too harsh.


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

8Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 1:12 pm

duck

duck
Life time member
Life time member
I've always used the Honda SS-8 10W in all of my Ks and had good luck with that.  And I have a case of it on hand.

My K75 Frankenbrick has K11 forks with that in it and I've got no complaints.  But it's also got a K1100RS fairing and tank so its front end weighs a bit more than a K75S.

I've learned from past experience not to overfill forks (not massively - just 10 or so CCs) so I usually put in a little less in than recommended and then add a little more if needed.

And I'd forgotten that the good thing about K100RS4V and K1 forks is that they don't have that plate held in by dogs at the top of the springs like the later K11 forks so it's much easier to swap springs.

I have both the Wirth and Works Dual Rate springs on hand and I'm going to try the Wirth springs first.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

9Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 2:04 pm

Two Wheels Better

Two Wheels Better
Moderator
Moderator
One thing I strived for when putting together the BB was to balance the front and back ends, suspension-wise. I had Klaus Hueneke at EPM Performance in New Jersey US put together a Hyperpro unit with 15mm height adjustment, rebound damping and double locknut preload. I asked him to imagine the bike (a stock K1100RS) with one hundred pounds of weight removed and never carrying a passenger. When I received it the spring looked a bit weak and so I was fiddling round with the preload and for at least a year ran it far too firm, thinking that's what I had to do. It would hammer up my back and the bike felt twitchy. I was also using a front 60 series Pirelli Rosso Corsa tyre - the thinking being I needed to quicken the steering of the long wheelbase - rather than the stock 70 series, now remedied with a 120/70ZR17 Rosso Corsa II. It was only when I spun the double locknuts upwards step by step and reduced damping to less than the usual 50% of adjustment I usually use that it came into its own, and now, with the front end sporting 7.5W over 10W it is a beautifully supple beast that gets through the bends with aplomb. After an upcoming road trip, and needing to more thoroughly go over the two other sets of Marzocchi front ends I have, I will perhaps try some aftermarket springs in the front. I await your experience with these new springs.


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

10Back to top Go down   Wirth springs in 4V forks Empty Re: Wirth springs in 4V forks on Sat Jun 23, 2018 3:21 pm

Dai

Dai
Life time member
Life time member
I put a pair of Hyperpro progressives in the front of LFB and switched up to 10w fork oil. Night and day... add a RamShok at the rear end and it felt like someone had handed me a brand new bike with all the old scratches on it.


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1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

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