Forks very stiff after oil change

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Dec 4, 2016
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'04 ST1300 - Blue
I've searched and read dozens of posts but can't find exactly what I am looking for. Just finished replacing my fork oil and took the bike out for a spin. Pleasantly surprised but a bit perplexed at the results. The fork seems much stiffer now but not uncomfortably so. I used the Honda SS8 (10wt oil) that the guy at the dealership said was spec but I've read some places that the stock oil is closer to 7.5wt. I'm guessing the online source is right but was hoping someone could confirm.

Just to clarify, I didn't change the springs and I filled to 62mm from the top of the tube when collapsed with the springs in to lighten things up a bit (less oil, softer rebound, right?). Was planning to increase preload at some point but the feel I have now is very similar to more preload anyway. I'm only ~155lbs in gear so don't get close to testing the high end of the spring rate.

Any feedback? Is this normal with the Honda SS8 oil?

Thanks
 

dduelin

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Oil height is measured tube and cartridge collapsed but without spring. Oil height is much too high.

Stock oil from factory is SS-8.
 
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Cvillechopper
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I'm not sure I follow. Measuring to 62mm from the top with the spring in would mean that the oil would be LOWER when I take the spring out and measure.

Oil height is measured tube and cartridge collapsed but without spring. Oil height is much too high.

Stock oil from factory is SS-8.
 

dduelin

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I did get it backwards...oops.

The stock oil level is 62 mm with the spring out. I'm no help if the action is too harsh. If everything is stock then the lower oil level should make the last 1/3rd of travel less progressive therefore less harsh than the stock factory set up.

Edit: Because oil level primarily works on the last 1/3rd of travel changing it doesn't give the benefits that correct spring rate and preload do.
 
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Cvillechopper
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OK. That's what I thought and is why I'm stumped. It's not overly harsh, just stiffer than I anticipated. Bike only has ~15K original miles on it so I wasn't expecting that the original fork oil would be trashed and it didn't look too bad when I dumped it. Just seems counter-intuitive to me.

I did get it backwards...oops.

The stock oil level is 62 mm with the spring out. I'm no help if the action is too harsh. If everything is stock then the lower oil level should make the last 1/3rd of travel less progressive therefore less harsh than the stock factory set up.
 
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Cvillechopper
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I had a little build up in one fork when I pulled it but nothing worrying. Cleaned it before filling. The forks were much "bouncier" before the oil change. Even just taking her off the center stand and hitting the front brake would give several inches of sag then bounce back. Now, almost no compression coming off the stand, much less dive when braking moderately, and a bit stiffer feel on bumps. Pretty much what I was planning to do with some extra preload but I just can't figure out why the oil change would have done this.

Could be excessive stiction you are seeing.
 
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I had a little build up in one fork when I pulled it but nothing worrying. Cleaned it before filling. The forks were much "bouncier" before the oil change. Even just taking her off the center stand and hitting the front brake would give several inches of sag then bounce back. Now, almost no compression coming off the stand, much less dive when braking moderately, and a bit stiffer feel on bumps. Pretty much what I was planning to do with some extra preload but I just can't figure out why the oil change would have done this.
Now it sounds even more like fork stiction. Might want to do a search on that in the forum here. Has to do with the tightening sequence and re-installation of fork legs.
Maybe not, but I would look into that first.
 
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this is all I could find in a quickie search. I think there are newer instructions..not sure. Stolen from the web!

Insert the axle and spacers and drive it in from the left.

Put on the axle nut, but do not tighten.

Tighten the left (from the riders point of view) pinch bolts that clamp down on the axle (the two hex heads on the bottom, forward facing surface of the fork slider).

Then tighten the axle nut.

Now loosen the two bolts you tightened earlier.

Grab the front brake, and bounce the front forks up and down a couple of times.

Finally, tighten all 4 of the pinch bolts.
 
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Cvillechopper
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Thank you. I went back through the tightening sequence (forgot to bounce the forks the first time) and it is a bit better but still stiffer than before oil change. While out there I went back through my history with the bike in my head and think I have figured out what is the main culprit.

When I got the bike, it had been garaged for several years. I got it home, changed most of the fluids, and took her on a 300 mile round trip. Did great but I do remember thinking that the forks were a bit bouncy. Few days later I went to washer her up good for some pictures and found that the right fork had a fair amount of gunk built up on the brakes and top of the fork leg. Seal was leaking. When I dumped the fluid I didn't take much notice of the volume that came out but I did notice the left fork seemed to have a little more. Pulled the seal and it looked perfect, just a little dirty so I gambled on reusing it (I know, not recommended). The leak must had been more of an issue than I thought. My baseline was probably not the stock feel and I've now got something closer to the intended fork response.

Helps if you get all the facts laid out and working through a problem on a forum like this is a great place for that. Thanks again!
 
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Honestly chopper I would go with a little lighter oil and start with the recommended amount. I would do this without the spring. Then you have a recordable measure. Or a base setup. Then you can go from there. I don't know how you measure the fork oil with the spring in. I guess there is a way though.
 
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Cvillechopper
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I've used a few methods in the past to measure the fork oil that don't really matter if the spring is in or not. My favorite is to use a bit of clear tubing attached to a 90 degree connector. Mark your distance down from the surface on the connector. I usually put a few marks on either side of my goal so I know how close I am. It slides down past the spring, no problem. Might pull the forks and top them off after a few longer rides. Need to see if this seal is going to hold up. If I have to replace the seal, might as well do it at the same time.

Oh, if I'm not being too picky about the exact measurement I just fill the tube up to where I know it's above the level, cut the tubing to the desired distance (62mm in this case) and used my hand-held pump to draw out the extra. Assuming you have no leaks and nothing drips back down when you stop pumping, the level will be right on mark...


Honestly chopper I would go with a little lighter oil and start with the recommended amount. I would do this without the spring. Then you have a recordable measure. Or a base setup. Then you can go from there. I don't know how you measure the fork oil with the spring in. I guess there is a way though.
 
Joined
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Messages
471
Location
CT USA
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07 ST1300
I've used a few methods in the past to measure the fork oil that don't really matter if the spring is in or not. My favorite is to use a bit of clear tubing attached to a 90 degree connector. Mark your distance down from the surface on the connector. I usually put a few marks on either side of my goal so I know how close I am. It slides down past the spring, no problem. Might pull the forks and top them off after a few longer rides. Need to see if this seal is going to hold up. If I have to replace the seal, might as well do it at the same time.

Oh, if I'm not being too picky about the exact measurement I just fill the tube up to where I know it's above the level, cut the tubing to the desired distance (62mm in this case) and used my hand-held pump to draw out the extra. Assuming you have no leaks and nothing drips back down when you stop pumping, the level will be right on mark...
Whatever works for you. I'm no expert on this. My take is that the higher level reduces the air chamber which acts a bit like preload. So you reduced it. It shouldnt be stiffer unless you had old horse piss in there before. Or maybe as you say it just leaked out.
Since I got a seal saver I have not changed a fork seal. So maybe you OK in that regard.
But as I say, I am not an expert. I havent even had my fork legs off this bike. I think mine are over dampened though.
 
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