Head Bearings & Fork Oil Completed - Help!

[durty3]

It was a great weekend in my shop! On Saturday I gave my bike, and my brothers, an oil change, chain clean/lube and wash. Yesterday was the big phase II.

I had the All Balls steering head bearing kit and a liter of Bel Ray 10 weight fork oil. Went over to my friends shop where I do motorcycle work--it is such a joy to have an air compressor, welder, press, car lift and full compliment of Snap-On tools.

Started by taking apart the front end--this was a breeze. Fork legs came right off and the triple tree slid right out. The lower bearing was total junk, now we know why it was clunking!

Removing the lower race: this is what I was nervous about and seems to be the most difficult/time consuming task. My friend, the professional mechanic got out his pneumatic chisel gun and had it off in about 30 seconds. No scratches to the stem either! He wanted to use heat to pop it off, but I wouldn't let him.

Installing new lower bearing: easy, we had a perfectly sized pipe and a 3 pound sledge.

Fork oil replacement: the old oil smelled rank and was milky as could be. I drained them for over an hour and then refilled. This process was easy with 4 hands, although admittedly--tedious. Right at the 5.28" mark in both fork.

Buttoned everything up and hopped on the bike. My initial impression is wow, these forks are super spongy now! Took it for a short ride and it runs smoothly, but a noticeable clunk. Oops, didn't torque down the handlebar nut. Got that torqued and another short ride, still a little clunk. Called over one of the mechanics and took off the handlebars, he then tightened up the nuts that secure the stem--told me to eat my Wheaties, they weren't nearly tight enough. Then tightened the handlebar nut securely and went on another ride. No clunk!

QUESTION: after reading on the this forum I was hopeful for a better damping action, but now it feels VERY spongy. I rode the bike for about 45 minutes after all of the test rides were complete and it runs real nice, but it is super bouncy at rest. I can't notice it as much when riding. I failed to measure the spring length when outside the forks. What might cause this, is it normal? When the old oil is super milky, does it actually make the forks "stiffer"?

It’s an ‘04 with 2 previous owners, 16k miles on the clock. I bought it 2 years ago from an older gentleman who owned it for 2 years. He was a small guy and also had a Harley and Corvette in his garage. I myself am 6 feet and 165 pounds, never ride hard.

Maybe nothing is wrong, or maybe something is very wrong, what do you all think?

THANKS!!!

 

[FinalImpact]

In the quote from MIA friend [MENTION=21015]darius[/MENTION] its all in the details.

At glance it looks like the Belray product has some variation. Take a look here. What the OEM says it is, vs what others calculated. Looks to the left column for 40c temp's (we're not racing) and compare what the Manuf reported vs the "Recalculated" values.... You might need to dump this and try something else.

In short; if the valving actually controlled the damping rates, you don't have to run higher viscosity fluids. But, OEM forks are not adjustable so your only allies are viscosity and fill level. You can add more oil to decrease the air volume and it should help (~1.0" higher). Its just can't be less than the stroke length or you risk sucking air in. But most find the initial spring rates to be below what is required (i.e. consume a lot of travel just from sitting it). Thus new springs and oil make it basically OK for most. Its quick, easy and is the best bang per buck until you decide you need more and spend more...

From this thread....

Yamaha did not design the forks to work with 15W oil. I found it so heavy it slowed down the action of the forks so much they could not react to bumps leading to a very harsh ride.

It's better to review viscosity ratings when choosing fork oil. Here's a chart I used to make an informed decision. I marked Yamaha 01 which is what the manufacturer recommends, the Silkolene I went with and where the 15W oils are.

 

[durty3]

Thanks for that detailed information!

It looks like the recalculated VI for the Bel Ray 10 wt is 123, still higher than the stock Yamaha of 96. Did I get that correct?

If so, why was it stiffer with the old oil that I drained? Maybe the previous owner actually changed to an oil with an even higher VI spec? Or does the old milky sludge I drained have a high damping effect?

I would hate to have to rip apart the front end again. I am thinking of a couple of options as you say.

1) Easiest method is to add about an inch of oil as you say and see how it feels. I could add more 10 weight, or maybe go to 20 weight (or higher) and try and gain as much ground as possible?

2) With the forks still on the bike, pull out the stock springs and go to Racetech's (or others)? I thought about this previously, but hoped changing the oil would make me happy. Racetech site says my 168 pound body should have a 0.85 kg/mm spring instead of the stock .77kg/mm. I can afford the $130 price tag, just figured I didn't need too.

3) Take the forks off, drain them and go with a different oil completely? I am not sure what to choose though for quality ride performance!

Thanks!

 

[FinalImpact]

Notice the night and day difference from BR 10w vs BR 10w HV1? Wow!

Back to your point, any tell tale signs someone has been there before you? Like top caps being mared by a wrench slipping?
Or perhaps once the air bubbles escapped, the level was too low? IDK!

All of the above are options. Step one, add more oil. If results are poor, try a different flavor? Maybe Yamaha 10w? And if still below expectations, springs... 0.85kg/mm sounds right for you.

 

[FIZZER6]

I just did my fork oil 1 month ago. I used 10 wt. as well. My forks were noticeably stiffer, less compression under heavy braking and feel great! My guess is you may have assembled the fork incorrectly?

Did you use some type of tool to hold the damper assy. in the fork while you tightened up the lower bolt that holds it in place? Are you sure you put the spacer, washer and spring in the right order?

My bike is a 2006 so I have the exact same forks. Note: the tighter coils on the spring go UP in the fork!

 

[durty3]

No tell tale signs of the forks having been opened previously!

The springs came out tighter coils pointing downward, so I did reassemble them that way--would that cause this light of a feeling? It would be relatively easy to flip them while the forks are on the bike, or even toss them for Racetech's.

As far as the assembly procedure, I did not completely break down the forks. I took off the top cap, slid out the spacer, washer and the spring. I didn't touch the dampers as my seals look fine. Thoughts?

Funny thing about my choice of fork oil. I was in a bind on Saturday afternoon trying to find oil so I could do the work on Sunday. Only place that had a liter available was the Yamaha dealership. I went to pick it up thinking it would be Yamalube, but nope--they sold me the Bel Ray!

Thanks!

 

[FIZZER6]

No tell tale signs of the forks having been opened previously!

The springs came out tighter coils pointing downward, so I did reassemble them that way--would that cause this light of a feeling? It would be relatively easy to flip them while the forks are on the bike, or even toss them for Racetech's.

As far as the assembly procedure, I did not completely break down the forks. I took off the top cap, slid out the spacer, washer and the spring. I didn't touch the dampers as my seals look fine. Thoughts?

Funny thing about my choice of fork oil. I was in a bind on Saturday afternoon trying to find oil so I could do the work on Sunday. Only place that had a liter available was the Yamaha dealership. I went to pick it up thinking it would be Yamalube, but nope--they sold me the Bel Ray!

Thanks!

Funny, my 2006 springs were also in with the tighter coils at the bottom which is wrong! The 2004-2006 manual specifically says to put the tighter coils at the top and 2007+ bikes have the tighter coils up top. I put mine back in tighter on top and not sure if that had something to do with my improved suspension feel but I can tell you that with Maxima 10WT fork oil and springs put back in correctly my bike feels like a completely different bike, much improved! :thumbup:

 

[FinalImpact]

FWIW its not apples to apples. Stock springs are dual rate and are nonlinear. 0.77 - 1.25 or somthing like that. There is huge difference. Making both ends linear makes the bike track more predictably in the corners...

As for stock springs, when inverted they add to unsprung weight (weight thats active with suspension movement) and the 1.25 rate is being acted upon by every little bump as it has to slide the whole spring in the tube before it compresses the lighter rate which is at the top (backwards to best practice). So it does help having them installed correctly.

 

[FinalImpact]

Exhibit A... Spring in motion.... Why close coils are at the fixed end, not the active end.
A different view of the XJR: [ame]http://www.youtube.com/watch?v=-WUqDJPwZv0[/ame]

Thanks [MENTION=372]OZXJR[/MENTION] great timing!

 

[durty3]

OK, so I definitely need to flip the springs, makes perfect sense! This should be pretty easy while the forks are still on the bike. While I am in there should I add an inch of oil, or should I really do this in stages?

Nobody seems to be pushing me to get new springs???

 

[FinalImpact]

If you can safely collapse the nose, it would nice to double check the level just for kicks an grins. Be VERY CAREFUL as a mistake could land your bike on the ground! In addition the angle is going skew an accurate measurement so its moot point.

Roughly speaking you need to add 1oz to each to increase fill level 1.0"

 

[durty3]

If you can safely collapse the nose, it would nice to double check the level just for kicks an grins. Be VERY CAREFUL as a mistake could land your bike on the ground! In addition the angle is going skew an accurate measurement so its moot point.

Roughly speaking you need to add 1oz to each to increase fill level 1.0"

I plan to add an ounce to each tube and flip the springs. See where that gets me.

Thanks for all the help!