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1Back to top Go down    41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 9:37 am

Snod Blatter

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Hi all, the "S" Brembo forks on my '89 SE are, well, let's be kind and say they're simply beyond help. They leak so much that the oil seeps out the bottom of the gaiters and wets the top half of the legs..

I've lusted after some K75 Showa forks for a while and am pleased to see there's a pair on ebay and that they even have the fork brace mounts so they should be a simple drop-in replacement, though I don't know if that extra ABS sensor bracket will get in the way. Or if I can use it, perhaps? Anyway, the big problem people talk about is that the Showa stanchions are slightly smaller in diameter - has anyone clamped them up with the older yokes successfully?

I'm not too concerned if it's a big no-no and the later yokes are absolutely required as the steering head bearings are a bit notchy so I could possibly replace the whole lot but I'd rather just drop the forks in and carry on, at least for now.

Oh and if someone has a pair of Showas and would take less money, do let me know Cool


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1989 K100RS SE ABS 8v VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

2Back to top Go down    Re: 41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 10:22 am

RicK G

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They are K100 16V 0r K1100 and will be 41.7mm


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

3Back to top Go down    Re: 41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 10:23 am

BobT

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Would it not be much better and cheaper to just change the fork seals? Most of them last a short while apart from the ones that you buy from BMW. A few have found that they are the only ones that last.

    

4Back to top Go down    Re: 41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 10:37 am

Snod Blatter

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@RicK G wrote:They are K100 16V 0r K1100 and will be 41.7mm
Ah, haha. Thanks!

BobT - it's beyond seals. The stanchions have huge scores in the area of travel and the inside of the leg will be just as bad. It has been this way since I bought it, and the lack of oil means the front is really quite soggy. I wonder if it also contributes to the head shake I can get on worn tyres when coasting on overrun between 60 and 50mph.


__________________________________________________
1989 K100RS SE ABS 8v VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

5Back to top Go down    Re: 41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 10:45 am

Born Again Eccentric

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@Snod Blatter wrote:
... and the lack of oil means the front is really quite soggy. I wonder if it also contributes to the head shake I can get on worn tyres when coasting on overrun between 60 and 50mph.
The head shake is more likely to be due to your worn head bearings - but soggy forks won't improve the situation and will affect cornering stability - especially if there are different levels of oil left in each fork!


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Paul

"Heidi" K100LT 1991 (Grey) (VIN 0190172 Engine No. 104EB 2590 2213) - 5th owner. January 2014 (34,000 - 61,000 miles and counting....)
"Gretel" K100LT 1989 (Silver Grey) (VIN 0177324 Engine No. 104EA 2789 2211) - 4th+ owner. September 2015 (58,500miles and counting....). Cat C Insurancewrite-off rebuild Feb 17
"Donor" K100LT 1990 (Red) (VIN 0178091 Engine No. 4489 2024) - 6th & final owner (crash write-off now donor bike). June 2012 (73,000 miles) to November 2013 (89,500 miles)
    

6Back to top Go down    Re: 41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 10:56 am

Snod Blatter

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Ha, I have no idea how much oil is in each one. All I know is the oil level is low enough that they've stopped leaking Laughing

It's just a little centre notch, very pronounced with the forks and wheel removed but hard to find if all the weight is bolted on. No MOT tester has mentioned it yet. Is the chassis really so marginal? As an aside, if anyone else has head shakes like this then fit a Michelin Pilot Activ to the front - I've not had a shake since. Marvellous.


__________________________________________________
1989 K100RS SE ABS 8v VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

7Back to top Go down    Re: 41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 11:30 am

BobT

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My 16v has a steering damper as standard, but I would not change a tyre to control a head shake when the steering bearings are shot, I would change them first.

    

8Back to top Go down    Re: 41mm Showa forks in 41.3mm yokes on Sun Jan 08, 2017 7:11 pm

RicK G

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If you can feel the notch then it's time to renew the bearings.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

9Back to top Go down    41 mm Showa forks in 41.3 mm yokes on Wed Jan 11, 2017 3:51 am

audibob

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Like you Snod,

my last two Mot testers failed to notice a very slight notch on my head bearings with the bars centralised.

I do not get any shake on the bars, buy I do get a feel that the front is not as tight as it should be, whether this is how the bike is, or the bearings need changing sooner rather than later.

My head bearings are next on my list anyway.

I would like some fancy forks and twin pot brembos , but money needs spending elsewhere and I do not ride that fast around the bends to justify it.

The K1100 throttle bodies I have , ( yet to be fitted ) plus a timing tweak will give me a bit more occasional grunt without having to spend more money on the steering department..

Bob


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