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Fork oil stink

 

Checking steering head bearings (which are surprisingly good… just cleaned and greased them) and decided to check fork seals and oil. ?Boy did that old oil stink!?

removed the dampers … made the ‘handle tool’ out of a 12” long 5/8th bolt (its hex head is 240mm, just right), and using a 5/8th coupling nut, connected another 5/8th bolt (5” this time) with a couple 5/8th nuts to double nut the coupling. ?Worked fine.

the fork- bottom 8mm bolt was pretty stuck but some heat and PB blaster did the trick. ?One of the fork bolts was missing its copper washer… suggesting a previous owner lost it and failed to replace it with a new one. ?

my question concerns that split plastic washer/seal on the top of the damper. ?Does it need to be replaced and what is the part number? ?Both of my old ones look fine, but I didn’t see a part number in the parts manual. ?
?
I’ve ordered new 8mm bolts as well since one of them is pretty bungee up.
?
V
 

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Hey V -

I’m thinking about this job for the winter… I’m definitely going to store that 5/8 bolt idea away!

I’m wondering what “split plastic washer/seal” you mean… Is it shown somewhere in a manual photo or diagram, even without a part number? ?I’m thinking I’ll replace all the bushes and seals in my forks (since I know they’re old and on rare occasions I hear some odd noises over bumps - and it’s not the steering bearings) - but as far as I know there’s no kit of parts available. ?Anyone have a list? ?Or maybe I’ll need to make my own as I dismantle…

~ Matt


On Oct 28, 2024, at 9:55 PM, vijahast via <vijahast@...> wrote:

Checking steering head bearings (which are surprisingly good… just cleaned and greased them) and decided to check fork seals and oil. ?Boy did that old oil stink!?

removed the dampers … made the ‘handle tool’ out of a 12” long 5/8th bolt (its hex head is 240mm, just right), and using a 5/8th coupling nut, connected another 5/8th bolt (5” this time) with a couple 5/8th nuts to double nut the coupling. ?Worked fine.

the fork- bottom 8mm bolt was pretty stuck but some heat and PB blaster did the trick. ?One of the fork bolts was missing its copper washer… suggesting a previous owner lost it and failed to replace it with a new one. ?

my question concerns that split plastic washer/seal on the top of the damper. ?Does it need to be replaced and what is the part number? ?Both of my old ones look fine, but I didn’t see a part number in the parts manual. ?
?
I’ve ordered new 8mm bolts as well since one of them is pretty bungee up.
?
V
 

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Philippe Parent
66350 Toulouges (France)
+33 (0) 659651310

 

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Have you looked at a parts dealer list such as on this website of CMS.


On 30/10/2024 12:30, Matthew Szostak via groups.io wrote:

Hey V -

I’m thinking about this job for the winter… I’m definitely going to store that 5/8 bolt idea away!

I’m wondering what “split plastic washer/seal” you mean… Is it shown somewhere in a manual photo or diagram, even without a part number? ?I’m thinking I’ll replace all the bushes and seals in my forks (since I know they’re old and on rare occasions I hear some odd noises over bumps - and it’s not the steering bearings) - but as far as I know there’s no kit of parts available. ?Anyone have a list? ?Or maybe I’ll need to make my own as I dismantle…

~ Matt


On Oct 28, 2024, at 9:55 PM, vijahast via <vijahast@...> wrote:

Checking steering head bearings (which are surprisingly good… just cleaned and greased them) and decided to check fork seals and oil. ?Boy did that old oil stink!?

removed the dampers … made the ‘handle tool’ out of a 12” long 5/8th bolt (its hex head is 240mm, just right), and using a 5/8th coupling nut, connected another 5/8th bolt (5” this time) with a couple 5/8th nuts to double nut the coupling. ?Worked fine.

the fork- bottom 8mm bolt was pretty stuck but some heat and PB blaster did the trick. ?One of the fork bolts was missing its copper washer… suggesting a previous owner lost it and failed to replace it with a new one. ?

my question concerns that split plastic washer/seal on the top of the damper. ?Does it need to be replaced and what is the part number? ?Both of my old ones look fine, but I didn’t see a part number in the parts manual. ?
?
I’ve ordered new 8mm bolts as well since one of them is pretty bungee up.
?
V

 

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Sure have! ?I also have a digital copy of a parts book, which includes the “exploded” diagram and all the parts and their numbers - and descriptions which don’t really reveal to me which parts would be replaced as part of a service. ?I assume that I won’t know for sure until I dismantle and examine… for example the bushing at the bottom of the inner fork tube (I think the service manual refers to this as a “guide bushing”?) - might be worn out or might be ok…

And now that I read a little bit further on the service manual page, I see the following under “Front Fork Assembly”:



… which leads me to conclude, yet again, that if I just put in a little extra effort, I could save everyone a lot of hassle…



On Oct 30, 2024, at 11:42 AM, Rev via <keith.kkr@...> wrote:

Have you looked at a parts dealer list such as on this website of CMS.


On 30/10/2024 12:30, Matthew Szostak via wrote:
Hey V -

I’m thinking about this job for the winter… I’m definitely going to store that 5/8 bolt idea away!

I’m wondering what “split plastic washer/seal” you mean… Is it shown somewhere in a manual photo or diagram, even without a part number? ?I’m thinking I’ll replace all the bushes and seals in my forks (since I know they’re old and on rare occasions I hear some odd noises over bumps - and it’s not the steering bearings) - but as far as I know there’s no kit of parts available. ?Anyone have a list? ?Or maybe I’ll need to make my own as I dismantle…

~ Matt


On Oct 28, 2024, at 9:55 PM, vijahast via <vijahast@...> wrote:

Checking steering head bearings (which are surprisingly good… just cleaned and greased them) and decided to check fork seals and oil. ?Boy did that old oil stink!?

removed the dampers … made the ‘handle tool’ out of a 12” long 5/8th bolt (its hex head is 240mm, just right), and using a 5/8th coupling nut, connected another 5/8th bolt (5” this time) with a couple 5/8th nuts to double nut the coupling. ?Worked fine.

the fork- bottom 8mm bolt was pretty stuck but some heat and PB blaster did the trick. ?One of the fork bolts was missing its copper washer… suggesting a previous owner lost it and failed to replace it with a new one. ?

my question concerns that split plastic washer/seal on the top of the damper. ?Does it need to be replaced and what is the part number? ?Both of my old ones look fine, but I didn’t see a part number in the parts manual. ?
?
I’ve ordered new 8mm bolts as well since one of them is pretty bungee up.
?
V


 

When I pulled the forks apart to check, clean, and replace the oil, the thin plastic split spacers could not be re-fitted, so they were left out. It was too fiddly a job. I then made two one-inch-long round spacers out of a metal pipe, using them to precompress the fork springs while screwing?in the top nuts. No more bottoming on bumps. They are known as poor man's progressive springs. I also use tyre sizes 110/90-19 front and 140/80-18 rear rather than the standard sizes. Seems to ride better.

Virus-free.

Den tors. 31. okt. 2024 kl. 04.42 skrev Rev via <keith.kkr=gmail.com@groups.io>:

Have you looked at a parts dealer list such as on this website of CMS.


On 30/10/2024 12:30, Matthew Szostak via wrote:
Hey V -

I’m thinking about this job for the winter… I’m definitely going to store that 5/8 bolt idea away!

I’m wondering what “split plastic washer/seal” you mean… Is it shown somewhere in a manual photo or diagram, even without a part number?? I’m thinking I’ll replace all the bushes and seals in my forks (since I know they’re old and on rare occasions I hear some odd noises over bumps - and it’s not the steering bearings) - but as far as I know there’s no kit of parts available.? Anyone have a list?? Or maybe I’ll need to make my own as I dismantle…

~ Matt


On Oct 28, 2024, at 9:55 PM, vijahast via <vijahast@...> wrote:

Checking steering head bearings (which are surprisingly good… just cleaned and greased them) and decided to check fork seals and oil.? Boy did that old oil stink!?

removed the dampers … made the ‘handle tool’ out of a 12” long 5/8th bolt (its hex head is 240mm, just right), and using a 5/8th coupling nut, connected another 5/8th bolt (5” this time) with a couple 5/8th nuts to double nut the coupling.? Worked fine.

the fork- bottom 8mm bolt was pretty stuck but some heat and PB blaster did the trick.? One of the fork bolts was missing its copper washer… suggesting a previous owner lost it and failed to replace it with a new one. ?

my question concerns that split plastic washer/seal on the top of the damper.? Does it need to be replaced and what is the part number?? Both of my old ones look fine, but I didn’t see a part number in the parts manual. ?
?
I’ve ordered new 8mm bolts as well since one of them is pretty bungee up.
?
V

 

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Huh. ?I look forward to finding out what these split plastic washers/seals/spacers are all about…


On Oct 30, 2024, at 12:09 PM, Peter Wainwright via <pete.wainwright.nz@...> wrote:

When I pulled the forks apart to check, clean, and replace the oil, the thin plastic split spacers could not be re-fitted, so they were left out. It was too fiddly a job. I then made two one-inch-long round spacers out of a metal pipe, using them to precompress the fork springs while screwing?in the top nuts. No more bottoming on bumps. They are known as poor man's progressive springs. I also use tyre sizes 110/90-19 front and 140/80-18 rear rather than the standard sizes. Seems to ride better.

Virus-free.

Den tors. 31. okt. 2024 kl. 04.42 skrev Rev via <keith.kkr=gmail.com@groups.io>:

Have you looked at a parts dealer list such as on this website of CMS.


On 30/10/2024 12:30, Matthew Szostak via wrote:
Hey V -

I’m thinking about this job for the winter… I’m definitely going to store that 5/8 bolt idea away!

I’m wondering what “split plastic washer/seal” you mean… Is it shown somewhere in a manual photo or diagram, even without a part number?? I’m thinking I’ll replace all the bushes and seals in my forks (since I know they’re old and on rare occasions I hear some odd noises over bumps - and it’s not the steering bearings) - but as far as I know there’s no kit of parts available.? Anyone have a list?? Or maybe I’ll need to make my own as I dismantle…

~ Matt


On Oct 28, 2024, at 9:55 PM, vijahast via <vijahast@...> wrote:

Checking steering head bearings (which are surprisingly good… just cleaned and greased them) and decided to check fork seals and oil.? Boy did that old oil stink!?

removed the dampers … made the ‘handle tool’ out of a 12” long 5/8th bolt (its hex head is 240mm, just right), and using a 5/8th coupling nut, connected another 5/8th bolt (5” this time) with a couple 5/8th nuts to double nut the coupling.? Worked fine.

the fork- bottom 8mm bolt was pretty stuck but some heat and PB blaster did the trick.? One of the fork bolts was missing its copper washer… suggesting a previous owner lost it and failed to replace it with a new one. ?

my question concerns that split plastic washer/seal on the top of the damper.? Does it need to be replaced and what is the part number?? Both of my old ones look fine, but I didn’t see a part number in the parts manual. ?
?
I’ve ordered new 8mm bolts as well since one of them is pretty bungee up.
?
V




 

I do not understand why Kawasaki did not include a drain plug at the bottom of each fork's outer housing.

Virus-free.

Den tors. 31. okt. 2024 kl. 05.09 skrev Peter Wainwright via <=gmail.com@groups.io>:

When I pulled the forks apart to check, clean, and replace the oil, the thin plastic split spacers could not be re-fitted, so they were left out. It was too fiddly a job. I then made two one-inch-long round spacers out of a metal pipe, using them to precompress the fork springs while screwing?in the top nuts. No more bottoming on bumps. They are known as poor man's progressive springs. I also use tyre sizes 110/90-19 front and 140/80-18 rear rather than the standard sizes. Seems to ride better.

Virus-free.

Den tors. 31. okt. 2024 kl. 04.42 skrev Rev via <keith.kkr=gmail.com@groups.io>:

Have you looked at a parts dealer list such as on this website of CMS.


On 30/10/2024 12:30, Matthew Szostak via wrote:
Hey V -

I’m thinking about this job for the winter… I’m definitely going to store that 5/8 bolt idea away!

I’m wondering what “split plastic washer/seal” you mean… Is it shown somewhere in a manual photo or diagram, even without a part number?? I’m thinking I’ll replace all the bushes and seals in my forks (since I know they’re old and on rare occasions I hear some odd noises over bumps - and it’s not the steering bearings) - but as far as I know there’s no kit of parts available.? Anyone have a list?? Or maybe I’ll need to make my own as I dismantle…

~ Matt


On Oct 28, 2024, at 9:55 PM, vijahast via <vijahast@...> wrote:

Checking steering head bearings (which are surprisingly good… just cleaned and greased them) and decided to check fork seals and oil.? Boy did that old oil stink!?

removed the dampers … made the ‘handle tool’ out of a 12” long 5/8th bolt (its hex head is 240mm, just right), and using a 5/8th coupling nut, connected another 5/8th bolt (5” this time) with a couple 5/8th nuts to double nut the coupling.? Worked fine.

the fork- bottom 8mm bolt was pretty stuck but some heat and PB blaster did the trick.? One of the fork bolts was missing its copper washer… suggesting a previous owner lost it and failed to replace it with a new one. ?

my question concerns that split plastic washer/seal on the top of the damper.? Does it need to be replaced and what is the part number?? Both of my old ones look fine, but I didn’t see a part number in the parts manual. ?
?
I’ve ordered new 8mm bolts as well since one of them is pretty bungee up.
?
V

 

? Is this photo, you can see the split white plastic gasket/spacer. ?It’s locatered at the top of the damper, its widest point. ?My guess is that it serves as a kind of piston ring… forms an oil seal and provides spacing between the damper and the inner cylinder.
?

 

I have both a digital and paper parts manual. ?I may be missing it, but I cannot find a clear picture of the white plastic damper ‘seal/spacer’. ?Fortunately, mine are fine. ?On an older triumph damper, there are O- ring type seals. ?The W650 does NOT have an O-ring … just that white plastic seal/spacer. ?

the W650 damper is very simple, just a tapered hollow tube with a few holes drilled near the bottom. ?

 

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Ah, now I see what you mean… yes, that cylinder, spring and “spacer” are all shown as a unit in the parts manual…


On Oct 30, 2024, at 12:36 PM, vijahast via <vijahast@...> wrote:

I have both a digital and paper parts manual. ?I may be missing it, but I cannot find a clear picture of the white plastic damper ‘seal/spacer’. ?Fortunately, mine are fine. ?On an older triumph damper, there are O- ring type seals. ?The W650 does NOT have an O-ring … just that white plastic seal/spacer. ?

the W650 damper is very simple, just a tapered hollow tube with a few holes drilled near the bottom. ?


 

Handle tool looks like this:
?
5/8 bolt, 12” long with 240mm hex-head
5/8 bolt, 5” long with 240mm hex-head
5/8 coupling bolt (between the bolts to connect them)
two 5/8 nuts to ‘double nut’/lock the coupling nut from turning while loosening or tightening?
?
works like a charm
?

 

Matthew, my fork seals aren’t leaking at all. ?I don’t know if they were replaced sometime in the last 24 years … but they are solid. ?Consequently, I don’t see the need.. it seems the W650 is a pretty solidly built bike. ?About as low stressed and reliable as it gets. ?

Some complain about the vibration around 3500 rpm… and I do feel it… but my last bike was a 70’s Bonneville. ?Now we’re talking vibration. ?Worse than that was a 73 sportster I had many years ago, that one made your hands numb after an hour or so (if you could keep it running).
?
In my opinion, the W bikes are the most faithful classic replicas made. They ?Really are classic bikes with modern reliability. ?

?
?
?

 

I like your ‘poor man’s’ progressive springs. ?The original metal spacer could easily be replaced with a metal pipe about an inch longer… or half an inch. ?Frankly, I’m trying to stick to stock as much as possible. ?But adding a bit more spacer does preload the fork springs … presumably stiffening them just a bit. ?

some have just used a 15w oil (or at least higher viscosity 10w oil) and like the results. ?But unless you drill bigger holes in the dampers … the heavier oil may be too stiff. ?I don’t know that my relaxed riding style requires stiffer suspension. ?In that case I’ll just get an old Ducati to play with

 

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V -

Agreed. ?However...

The one previous time I changed my fork oil, I found signs of something amiss, either with the forks themselves or the maintenance practices of a previous owner (I’m the third owner, as far as I know). ?When draining the oil, I found the quantities to be the same, but the oil that came out of each fork leg was strangely different: different color, seemingly slightly different consistency, and seemingly different amount of “sludge” in suspension. ?I rinsed them out and refilled them (same oil in both forks this time!); when “compressing" them to check the air gap (no main spring installed), I found that one side would remain fully compressed at the bottom of its travel, but the other side would rebound back up about a centimeter, as if there was a small spring (or spring action at least) at work. ?I had to physically hold the fork tube down to measure the air gap. ?I thought that strange as well.

After refilling, I discovered that filling the forks with the recommended oil quantities listed in the service manual resulted in an air gap measurement that was nowhere near the service manual spec. I don’t recall the exact numbers, but I think I would have had to almost double the oil volume in each leg in order to attain the specified air gap. ?Very strange (said in my best Allen Millyard voice). ?I engaged in a lengthy discussion on the W650 Facebook group about it, looking for evidence of a mistake in the manual, or evidence of a mistake I might have made, or other advice, and in the end no conclusion was reached - so I still don’t know if I have the right amount of fork oil.

Finally, recently I’m hearing and feeling a very occasional “clunk” from the front end when going over sudden heavy bumps or holes, at low speed. ?It’s not the forks bottoming out. ?I’ve done all the checks to discover looseness or play in the steering bearings and front wheel bearing (both were serviced at the same time as the last fork oil change), and found no issues.

So, seeing as I’m once again overdue for a fork oil change, it seems logical to disassemble the forks and inspect the internals while I have them off the bike anyway. ?And although my seals aren’t leaking, it seems like it would be a false economy to reuse the old seals rather than renew them while I’m in there…


On Oct 30, 2024, at 9:58 PM, vijahast via <vijahast@...> wrote:

Matthew, my fork seals aren’t leaking at all. ?I don’t know if they were replaced sometime in the last 24 years … but they are solid. ?Consequently, I don’t see the need.. it seems the W650 is a pretty solidly built bike. ?About as low stressed and reliable as it gets. ?

Some complain about the vibration around 3500 rpm… and I do feel it… but my last bike was a 70’s Bonneville. ?Now we’re talking vibration. ?Worse than that was a 73 sportster I had many years ago, that one made your hands numb after an hour or so (if you could keep it running).
?
In my opinion, the W bikes are the most faithful classic replicas made. They ?Really are classic bikes with modern reliability. ?

?
?
?

 

That is interesting… the only thing moving around is that damper spring. ?Without oil, you can hear it as you flip the forks over. ?The damper is fastened to the bottom of the outer tube, it isn’t moving. ?The damper spring just slides up and down the damper shaft. ?I don’t really know what it does exactly. ?

at any rate, I do hear it. ?Only thing that I can think of that would ‘clunk’ like that might be the spacer and/or spring. ?Perhaps a longer spacer might preload the spring a bit? ?I don’t know, just thinking out loud.
?
im curious to what you find out.
?
V

 

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It’s a winter project, so it might take awhile, but I will report back…


On Oct 31, 2024, at 10:43 AM, vijahast via <vijahast@...> wrote:

That is interesting… the only thing moving around is that damper spring. ?Without oil, you can hear it as you flip the forks over. ?The damper is fastened to the bottom of the outer tube, it isn’t moving. ?The damper spring just slides up and down the damper shaft. ?I don’t really know what it does exactly. ?

at any rate, I do hear it. ?Only thing that I can think of that would ‘clunk’ like that might be the spacer and/or spring. ?Perhaps a longer spacer might preload the spring a bit? ?I don’t know, just thinking out loud.
?
im curious to what you find out.
?
V

 

Yes Matthew a one inch longer spacer does the trick, done that on mine.?

Den fre. 1. nov. 2024 kl. 10.27 skrev Matthew Szostak via <gurdy4me=gmail.com@groups.io>:

It’s a winter project, so it might take awhile, but I will report back…


On Oct 31, 2024, at 10:43 AM, vijahast via <vijahast@...> wrote:

That is interesting… the only thing moving around is that damper spring.? Without oil, you can hear it as you flip the forks over.? The damper is fastened to the bottom of the outer tube, it isn’t moving.? The damper spring just slides up and down the damper shaft.? I don’t really know what it does exactly. ?

at any rate, I do hear it.? Only thing that I can think of that would ‘clunk’ like that might be the spacer and/or spring.? Perhaps a longer spacer might preload the spring a bit?? I don’t know, just thinking out loud.
?
im curious to what you find out.
?
V

 

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Peter - thanks… but… what does a one inch longer spacer accomplish in this instance?


On Oct 31, 2024, at 8:01 PM, Peter Wainwright via <pete.wainwright.nz@...> wrote:

Yes Matthew a one inch longer spacer does the trick, done that on mine.?

Den fre. 1. nov. 2024 kl. 10.27 skrev Matthew Szostak via <gurdy4me=gmail.com@groups.io>:
It’s a winter project, so it might take awhile, but I will report back…


On Oct 31, 2024, at 10:43 AM, vijahast via <vijahast@...> wrote:

That is interesting… the only thing moving around is that damper spring.? Without oil, you can hear it as you flip the forks over.? The damper is fastened to the bottom of the outer tube, it isn’t moving.? The damper spring just slides up and down the damper shaft.? I don’t really know what it does exactly. ?

at any rate, I do hear it.? Only thing that I can think of that would ‘clunk’ like that might be the spacer and/or spring.? Perhaps a longer spacer might preload the spring a bit?? I don’t know, just thinking out loud.
?
im curious to what you find out.
?
V




 

It pre compresses the damper springs making them less spongy, hence no bottoming over bumps. It's a trick we used on the Yamaha SR 500 back in the ,80s and 90s. Also known as "poor man's progressive springs". Progressive springs do the job at a cost and availability. But maybe what you're after I cannot answer as I now re- read your inquiry?
Peter.

Den fre. 1. nov. 2024 kl. 21.53 skrev Matthew Szostak via <gurdy4me=gmail.com@groups.io>:

Peter - thanks… but… what does a one inch longer spacer accomplish in this instance?


On Oct 31, 2024, at 8:01 PM, Peter Wainwright via <pete.wainwright.nz@...> wrote:

Yes Matthew a one inch longer spacer does the trick, done that on mine.?

Den fre. 1. nov. 2024 kl. 10.27 skrev Matthew Szostak via <gurdy4me=gmail.com@groups.io>:
It’s a winter project, so it might take awhile, but I will report back…


On Oct 31, 2024, at 10:43 AM, vijahast via <vijahast@...> wrote:

That is interesting… the only thing moving around is that damper spring.? Without oil, you can hear it as you flip the forks over.? The damper is fastened to the bottom of the outer tube, it isn’t moving.? The damper spring just slides up and down the damper shaft.? I don’t really know what it does exactly. ?

at any rate, I do hear it.? Only thing that I can think of that would ‘clunk’ like that might be the spacer and/or spring.? Perhaps a longer spacer might preload the spring a bit?? I don’t know, just thinking out loud.
?
im curious to what you find out.
?
V




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