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Discussion Starter · #1 ·
Having had the opportunity to ride a good few miles today, I have noticed that the front forks bottom out much too easily if the bike encounters a small pothole in the road (of which there are many in the UK after a freezing winter).

I also hear what I would describe as a "spring sound". I can almost replicate this sound whilst staionary by applying the front brake and bouncing the front end down. I wonder if there's enough fork oil in there??

Any guidance?

TIA Tom.
 

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I would just drain them and add new fork oil..... The "stock" oil back then was "fish oil", so it breaks down fairly easily......Do one fork at a time, and flush the old junk out with some kero, then re-drain....You will have to "bounce" on the front end to "pump' out the last remnants...........
 

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MadDogMcQ said:
So I just remove the caps and pour it in after draining? I'd normally use auto transmission fluid.
The "book" may call for ATF, don't remember.

Some folks just use fork oil, oddly enough.....
 

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Yep, pretty much..... It is more important to get equal amounts into each fork than to get exactly the recommended amount... Tranny fluid will work, but a heavier fork oil is better IMHO...
 

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I am working on my K5 forks at the moment and what I have found so far on this forum and elsewhere is that 160 cc (if the forks are totally dry) ATF oil, fork oil 15w or engine oil 15w40 is the way to go.
Quit a lot of people recommend 15w40 engine oil in old Honda forks and I don't really know why?

Your K1 forks may have different construction and use a different amount of oil.
 

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so again, even after reading the annotated manual about replacing fork oil i still have some basic questions. my forks have a small bolt at the bottom facing the outside, is this is where i "drain out" the old? without taking any of the fork assembly apart-i'd even prefer to leave them on? after flushing with acetone, as suggested in this post, i pour 285-295cc's of hydraulic fluid back in the top? i don't know why i was thinking it's more complicated than this but upon writing it all out, this is it? guess i'll get my liquid conversion "widget" working here on my computer and figure out how many ounces 285cc's is.

someone please confirm all of this though...
 

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uhohferris said:
my forks have a small bolt at the bottom facing the outside, is this is where i "drain out" the old? without taking any of the fork assembly apart-i'd even prefer to leave them on? after flushing with acetone, as suggested in this post....
That's your drain hole alright - you may need to take off the top bolt to break any vacuum, and allow it to drain.
Not sure that acetone is the best thing for rubber parts though........
 

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uhohferris said:
guess i'll get my liquid conversion "widget" working here on my computer and figure out how many ounces 285cc's is.

someone please confirm all of this though...
glass baby bottles are marked CC's and Oz.'s, easy to convert works for me :lol:
 

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Nice, thanks for the replies. I meant kerosene bill, that'll work, right?
 

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Remember to have the bike on the center stand and suport the front of the bike so it doesnt drop if you happen to take both top fork bolts off at the same time. You could have the front end crash into your fender if the bike isnt supported and you take both bolts off at the same time. Want to know how I know that?
:roll: Don
 

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Actually, can I get one final answer on exactly what fork fluid to get? ATF, oil, hydraulic something? Any concensus would be appreciated...
 

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uhohferris said:
Actually, can I get one final answer on exactly what fork fluid to get? ATF, oil, hydraulic something? Any concensus would be appreciated...

It may be an odd choice, but I use fork oil in my forks.......
 

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i really like how you don't have a sarcastic bone in your body bill. your a real straight shooter. i can honestly tell you i didn't even know fork oil existed, thanks for clearing that up...
 

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Standard Honda fork oil should suffice. I "think" that others here were going for 15wt. You'll have to swap weights of oil to conform to your needs though..


GB :mrgreen:
 

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uhohferris said:
i really like how you don't have a sarcastic bone in your body bill. your a real straight shooter. i can honestly tell you i didn't even know fork oil existed, thanks for clearing that up...
Didn't mean to come off sarcastic, sorry.

I just started with fork oil a really long time ago - I had bikes with serious road-race suspension, which you could "tune" for a specific application by using anywhere from 5 weight to 20 weight.

Old habits die hard......I currently use 10 weight in CB400T forks on a 450 K4.
Also using 15 weight in a CB200.
 

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FWIW I found these articles to be helpful when setting up my bike.

http://www.gasgas.com/Pages/Technical/trials-suspension-tips.html

If you really want to get technical and have your eyes glaze over check this out:

http://www.peterverdonedesigns.com/lowspeed.htm

Also FWIW I added a 5cm spacer to my forks to increase the pre-load a tad and use Bel-Ray 10wt fork oil in my CM400 forks. Firms them up and smooths them out nicely for me. I'm fairly light, weighing in at 145lb, so clearly you'll have to experiment a bit.

m
 
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