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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Dav_reece on May 23, 2014, 12:44:13 PM
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Hello
So I've been riding the K75 for about a month now and really enjoying my time on it. It was pretty badly out of tune and had to have some adjustments done to the fuel ratios to get her running smoothly, worth it!
So now I have a question for you. How springy are your front forks? Mine fell like there is little to no dampening happening. When I stop using front brakes only I get a little seasick from the bounce that happens at full stop. Since it is a new to me bike I was thinking of checking the front fork oil level this weekend, but extra info from you would be helpful. There is also a little sticktion issue with the forks that I will have to address in the future but that is for later.
Is there any dampening that happens with the stock fork? what should I be expecting?
any input would be helpful!
thanks
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Stock forks on the K75 are kind of wimpy. Changing the fork oil and ensuring the proper amount is in each leg may improve the situation. Changing from 7.5 to 10 weight may help some too. Spacers added to the top of the springs or new progressive wound springs will improve handling and rid you of some of the bounce.
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Mine are the opposite they feel stiff but its not stiction. ( forks move up and down when pushed and front brake is held) I noticed in the service history the last owner had new seals and fork oil added. My bike is a K75s and I have been told the "S" version has stiffer "sports springs" from factory. So maybe the 10wt fork oil they poured in is incorrect for the "S" version but a good idea on the LT and C. This summer I may drain and return to standard and give it a go. Or try Progressive Springs kit. but AT £80 a pair I shall try the cheaper things first.
First modification I ever did on front forks was on a RD400 we put 50pence worth of copper coins down each tube to stiffen the forks up. It doubled the price of the bike :hehehe
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There are several forks on different K75 years and models. You should update your signature with your bike specs.
I have RT "sport" forks (< 1991) on a naked K75 and they have always felt less than perfect. I put new seals and Progressive springs in after a few months of ownership, back when the bike had an RT fairing.
I have tried 10w and 7.5w oil.
I just rebuilt them again and replaced the inexpensive piston rings, and am trying 5w oil. I also cut out an inch of PVC spacers. They actually feel pretty good during normal riding now. They seem to respond and absorb better.
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I have changed the fork oil and put in some 10w... Aside from the mess I made in the garage (I wasn't terribly careful at times... lessons have been learned :dunno2:) I haven't felt much of a difference, a little less spring but nothing earth moving.
the seals are in good condition, as in they aren't leaking... I have a new set of BMW seals that I will eventually use in a rebuild. For now I will deal with the lack of dampening and enjoy the ride :riding:
My mechanic recommends the progressive springs if I really wanted to see a difference! they will go on a wishlist, priorities will determine if/when that happens.
Thanks all for your input!