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Discussion Starter · #1 ·
Hi everyone!
I have my very first 2006 VN 750 for about 2 months now and I have done so much light work on her. Recently I posted that I had some issues with the regulator so I order a MOSFET... And while I am waiting on it, I decided to go ahead change oil on the forks.
I had this problem too while braking (even slowly), it was going too deep of a dive. Yes I am big guy, but that was the most I have ever experienced on motorcycles. The bike has only about 5000 miles on it.
So, last night I ordered 15wt fork oil, after reading for awhile everywhere here or other forums about the fork oil.
I know on the manual says SAE10w-20……but I was wondering what could be done withoutchanging to progressive springs…so I went the cheap way and I want to see if I can increase the preload on the OEM ones (any recommendations on these would be very appreciated).

so…..
I started..and when it was time to drain the oil from the left side, it came out so much, about 380+ml , very very dark and thick. I am like , ok…they put more in it…and it’s probably the engine oil.
I started the right side…and red thin oil started coming out. As it drains it became more like a mix of the red and the other side’s black. About 370+ml.
What is your thoughts guys in this??
1) Could that have been one of the issues? Or they tried to put more to make it harder to dive and didn’t really work out??
2) Do you think I should put that much back? Or to stick with the recommendation??
3) The distance on the tubes while seated and while full extended on the center stand (prior oil change) its actually very much…a little over 4”!
Thanx in advance! Any tips appreciated! :)
 

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I used ATF in mine, and I believe the manual says 9" from the top. (?) Check me on that.

Before the change, the front was really springy, after, it's reasonably firm but still cushions the big bumps.

I suppose the original oil was around 10w, and judging by the color and horrible smell it must have been whale oil. It's used in some hydraulics. It was greyish to whitish, but there could have been accumulation of condensation over the 17 years. I'd guess my springy action was a combination of thinned, tired, and contaminated oil.

I've read about people adding a spacer on top of the spring, but have no experience with it.

Seems like adding a lot more oil would make it extremely firm. Think I'd try the recommended amount and see how it feels, not too hard to add more.

You'll want to pump the forks a bit to bleed air before taking a final measurement.
 

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Discussion Starter · #3 ·
I used ATF in mine, and I believe the manual says 9" from the top. (?) Check me on that.

Before the change, the front was really springy, after, it's reasonably firm but still cushions the big bumps.

I suppose the original oil was around 10w, and judging by the color and horrible smell it must have been whale oil. It's used in some hydraulics. It was greyish to whitish, but there could have been accumulation of condensation over the 17 years. I'd guess my springy action was a combination of thinned, tired, and contaminated oil.

I've read about people adding a spacer on top of the spring, but have no experience with it.

Seems like adding a lot more oil would make it extremely firm. Think I'd try the recommended amount and see how it feels, not too hard to add more.

You'll want to pump the forks a bit to bleed air before taking a final measurement.
Man!! Thank you again!!
yes…!! I was thinking to either use some spacers or cut a slightly bigger than the metal , pvc pipe .
I am glad to hear that you got some difference on the oil! I don’t might to feel it on the bumps, but I don’t like the dive every time I am braking!! Also Yes, oil level it’s about 230mm /9”.
Thanx again for the input!
 

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Y
Man!! Thank you again!!
yes…!! I was thinking to either use some spacers or cut a slightly bigger than the metal , pvc pipe .
I am glad to hear that you got some difference on the oil! I don’t might to feel it on the bumps, but I don’t like the dive every time I am braking!! Also Yes, oil level it’s about 230mm /9”.
Thanx again for the input!
[/QUOT
OU
Man!! Thank you again!!
yes…!! I was thinking to either use some spacers or cut a slightly bigger than the metal , pvc pipe .
I am glad to hear that you got some difference on the oil! I don’t might to feel it on the bumps, but I don’t like the dive every time I am braking!! Also Yes, oil level it’s about 230mm /9”.
Thanx again for the input!
You're welcome.

I wouldn't use pvc, you don't want anything that could suddenly let go, could throw you off balance at the wrong time.

Mine never bottomed out, but it kept rebounding maybe 50 ft or more after the bump.

It's just firm and steady now just with the oil change and correct level. Mine may have been low on oil, I didn't check, but it seems like I put in more than I got out.

I'm thinking the ATF is 20w, but I'd have to check, maybe it's 10w ? 15?
 

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Discussion Starter · #6 · (Edited)
@Knifemaker yes, I just finished them!
so, I was about to use two pieces of pvc with a 3/4” height, but it was really too hard to press it in.
So I used 3 washers on each side. I could find 1-1/2” an 1” ID, only 3/8” and I wanted to get it done.
So….. I didn’t want to put the washers down-between spring and metal piece of pipe, so I stuck 3 washers with a bolt in the middle. I put in on the top part, right below the top end cup(I don’t remember the actual name now :p).
I will have the pics down here.
Also yes I used the Maxima 15wt fork oil. It looks kinda thick but it’s so clear.
@Spockster , I end up using about 375-380ml of oil, to get to the point of 9” . I hope it works out.
First impression out of the stand and applying a lot of break (in the garage) looks more responsive and a bit firmer.
I will let you guys know when I take her for a ride!!
 

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Discussion Starter · #7 · (Edited)
Pics here:

first one is what I wanted to do…
Wood Eyewear Body jewelry Jewellery Circle


And this is what I end up doing.
I just didn’t want to have a stack of washers in the middle because of their size, maybe they could hold more oil up. Maybe it’s stupid , I didn’t know.. but I didn’t want to risk it. That way it’s on the very top straight below the top end. Of course the nuts are on the bottom.
White Motor vehicle Gas Automotive exterior Auto part
 

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Pics here:

first one is what I wanted to do…
View attachment 53827

And this is what I end up doing.
I just didn’t want to have a stack of washers in the middle because of their size, maybe they could hold more oil up. Maybe it’s stupid , I didn’t know.. but I didn’t want to risk it. That way it’s on the very top straight below the top end. Of course the nuts are on the bottom.
View attachment 53828
On my 1995V and 750 and my 1989 van 750 I chose to use the Progressive Springs they called for a spacer they recommended the PVC however the recommendation was for the industrial thickness which way is a much better spacer. I used 15 weight fork oil recommended oil to 9 inches below and used a bit of preload on the springs . Both bikes run fine and am pleased with result
 
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Discussion Starter · #12 ·
On my 1995V and 750 and my 1989 van 750 I chose to use the Progressive Springs they called for a spacer they recommended the PVC however the recommendation was for the industrial thickness which way is a much better spacer. I used 15 weight fork oil recommended oil to 9 inches below and used a bit of preload on the springs . Both bikes run fine and am pleased with result
Yeah, that’s where I saw the pvc pipe preload! But i didn’t want or have the budget now for this progressive spring change. I am glad that works great for you! Everyone seems to enjoying these!
 

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On my K75 BMW weighing around 530 lbs fuelled up, I tried different oils in the forks and lined up a test circuit for early morning runs with really tight bends, straights, sweeping curves and timed the results. I found 20/50 motor oil gave me the best ride, quickest times and good performance under braking! 180 lb rider.
 

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I would not suggest using that heavy of an oil in the Vulcan forks. I noticed just using a 15w was stiffer over a 10w, so something that thick would definitely shake your kidneys off. 🙄
Also “quickest times” means little, as everyone knows a stiffer suspension may result in faster lap times, but I’d say most Vulcan owners, and most cruiser owners would put comfort over a shaving a second or two off a lap time.
I always softened up my race bikes suspension for riding it around town.
When I installed my Progressive springs I used PVC spacers, these were the off white thicker wall type. No reason to believe they’d ever fail.
 

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Didn't even think of Schedule 40 PVC when I posted previously, it's a lot thicker walled.

Also was mistaken earlier, ATF is 10w not 15 or 20. Couldn't find fork oil anywhere local or not the weight I wanted. It's getting to be like Moly 60 and unicorns.
 

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Discussion Starter · #16 ·
@Knifemaker , I better use very heavy then to shake and get rid of if this stupid kidney stone I have…!!!!!!🤣😜

yeah I also think the 15w I put, is good. It’s way better than it was on response and a little stiffer. But still, I haven’t got it in a ride yet. Tried it only on my street here and then started the stator process…..
@Spockster , yes that’s the pvc pipe I was thinking to use, the thick one.
in a little bit I will have the moment of truth about my stator/balancers replacement…..
Putting the last thing together…
 

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@Knifemaker , I better use very heavy then to shake and get rid of if this stupid kidney stone I have…!!!!!!🤣😜

yeah I also think the 15w I put, is good. It’s way better than it was on response and a little stiffer. But still, I haven’t got it in a ride yet. Tried it only on my street here and then started the stator process…..
@Spockster , yes that’s the pvc pipe I was thinking to use, the thick one.
in a little bit I will have the moment of truth about my stator/balancers replacement…..
Putting the last thing together…
Good luck, and keep us posted.
 

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Good luck, and keep us posted.
[/QUOTE
@Knifemaker , I better use very heavy then to shake and get rid of if this stupid kidney stone I have…!!!!!!🤣😜

yeah I also think the 15w I put, is good. It’s way better than it was on response and a little stiffer. But still, I haven’t got it in a ride yet. Tried it only on my street here and then started the stator process…..
@Spockster , yes that’s the pvc pipe I was thinking to use, the thick one.
in a little bit I will have the moment of truth about my stator/balancers replacement…..
Putting the last thing together…
I would not suggest using that heavy of an oil in the Vulcan forks. I noticed just using a 15w was stiffer over a 10w, so something that thick would definitely shake your kidneys off. 🙄
Also “quickest times” means little, as everyone knows a stiffer suspension may result in faster lap times, but I’d say most Vulcan owners, and most cruiser owners would put comfort over a shaving a second or two off a lap time.
I always softened up my race bikes suspension for riding it around town.
When I installed my Progressive springs I used PVC spacers, these were the off white thicker wall type. No reason to believe they’d ever fail.
[/QUOT
Ummh! As I said I was just experimenting, but also with oils damping/rebound qualities are important too. The BMW was an "S" with dropped OEM Sport bars and always felt heavy at the front end. Of course when you get fork dive, all the angles of geometry change, frame, forks, weight distribution etc. Where the bike was astounding was Motorways and fast dual carriageways, you could sit @ 90 mph all day every day, if needed! Not too happy on twisty country roads though!
 
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