Author Topic: Fork oil renewal  (Read 681 times)

Offline cliff7

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Fork oil renewal
« on: August 10, 2020, 03:10:39 PM »
Decided to change front fork oil. Drained both no problem. Looked like relatively clean ATF to me. Anyway, on removing filler cap I expected to see the spring but about an inch below the top of the stanchion is what looks like some sort of plug with an internal hexagon about 13mm and there is no way I can pour the oil in. Any idea what is wrong please.
1978 CB400F2

Offline Nurse Julie

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Re: Fork oil renewal
« Reply #1 on: August 10, 2020, 03:29:50 PM »
It's not a standard fit but I have heard other people have fitted a plug to push the springs down, must have something to do with pre load, or damping or something similar 🤔🤔
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https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

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Offline Nurse Julie

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Re: Fork oil renewal
« Reply #2 on: August 10, 2020, 03:32:42 PM »
Here's a pic of what I think it is, maybe not exactly the same as yours but similar possibly

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LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Nurse Julie

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Re: Fork oil renewal
« Reply #3 on: August 10, 2020, 03:38:40 PM »
This is the type my friends have been fitting

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LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline cliff7

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Re: Fork oil renewal
« Reply #4 on: August 10, 2020, 04:09:16 PM »
Thanks. I'll see if I can undo it. (13mm hex key). I know a previous owner fiddled with the bike as the drive sprockets are not standard either (higher gearing).

Offline cliff7

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Re: Fork oil renewal
« Reply #5 on: August 11, 2020, 12:26:15 PM »
I found these in the top of the forks. Some sort of preload adjuster I presume. [ Guests cannot view attachments ]

Offline ka-ja

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Re: Fork oil renewal
« Reply #6 on: August 11, 2020, 03:15:45 PM »
There is a similar set up on the superdream 400 forks, often fitted to 400/4s to give comstar wheels and twin disc brakes.
  CB400N parts list https://www.cmsnl.com/honda-cb400n-1978-european-direct-sales_model15810/partslist/F08.html#.XzKpLB57mRs
« Last Edit: August 11, 2020, 03:23:00 PM by ka-ja »
nice bike,nothing in the bank

Offline Bryanj

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Re: Fork oil renewal
« Reply #7 on: August 11, 2020, 04:47:57 PM »
Cant remember those fitted to any sohc i worked on

Offline Nurse Julie

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Re: Fork oil renewal
« Reply #8 on: August 11, 2020, 05:03:52 PM »
They are defo an aftermarket part, or someone has made them specially for some reason. I take it your front forks are proper CB400/4 ones 🤔
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline K2-K6

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Re: Fork oil renewal
« Reply #9 on: August 11, 2020, 05:19:52 PM »
Many of the ideas like that are filtering out from cycle components,  particularly DH (downhill racing) as they are absolutely obsessed with modding/ adjusting anything.

The forks are often up around 40mm stanchion as well,  so bigger than our era bikes! 

Brakes too,  currently working on setups with floating discs,  four or six pot calipers with titanium pistons,  usually machined from billet.

But the forks,  there's just so much to adjust,  setup etc, that people get completely lost in what they are doing with all sort of weird mods, some very shonky, that some have a go at.

Offline cliff7

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Re: Fork oil renewal
« Reply #10 on: August 11, 2020, 06:49:05 PM »
As far as I know, the forks are standard apart from these which I have removed. (yet to try them on the road).
Yes, my bicycle forks have much more adjustment ( variable compression and rebound damping, variable positive and negative air springs and lock out). When I was fit enough to mountain bike they did make a difference. At the speeds I motorbike I won't notice the difference and I have been told the brakes are surplus too!

 

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