Front wheel hop feeling????

[TommyT]

I have a 1990 K75s with 45k+ miles. I have had the bike for 300+ miles. Right after I got it, I replaced the 12 years+ old tires with new Michelin V rated tires. At 35 to 45 I feel a hop in the front, it is worst around 45 and from there disappears to "almost" smooth over 50 mph. I had the wheel and it's balance checked by a different shop then the one that mounted it (thinking their machine was off) and that shop said it was balanced and true. I only feel this on smooth roads.

I am stuck to think what else could be wrong, help? Bearings are good and I just changed the fork oil.
 

[Chaos]

I'd check everything on the rear as closely as the front.  Bad shock, wheel balance, bearing, whatever back there can manifest itself in the front.  Check your head bearings also. 

[TommyT]

Thanks all, I was wondering if something in the rear could be felt like it was up front. The first shop that mount mounted the rear tire couldn't balance it, no adapter, so I rode it for a while without being balanced, had the hop. found another shop that could balance it and that made no difference. I will look into the swing arm bearings and shock and post what I find but it may be a few days before I can get into it.

[TommyT]

oh forgot to say that the front bearing seems good, smooth side to side and no play.

[wally.fisher]

oh forgot to say that the front bearing seems good, smooth side to side and no play.

I
Why don't you replace the front bearings? Then you know they're good.
If the problem persists then you may need head bearing adjustment or replacement., be systematic.


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[TommyT]

Is there there an easy way to check for play in the swing arm bearings? I did not see anything here on Motorbrick or elsewhere on the internet.


Front bearings replacement, why not? Well that something to consider with 45k miles but so far from what I can tell with wheel off is that there is no poly in them and they move side to side smoothly. It looks like a lot of work to replace them. I plan on doing a major tear down on the bike as I get to the end of the riding season. if more testing does not find something in the rear, I will consider the front bearing replacement.

[Laitch]

Is there there an easy way to check for play in the swing arm bearings?

Parts like motorcycle wheels or swing arms that rotate on bearings are generally designed to have no movement forward to aft or side to side. Trying to wobble them lightly in those directions will show if there is any play. Movement will be subtle so attention must be paid.

Front bearings replacement, why not? . . . what I can tell with wheel off is that there is no poly in them and they move side to side smoothly.

It's morning here so I might need more coffee. What is meant by poly and by side to side? Bearings should be fixed in their positions. Wheels should rotate smoothly but not move from side to side.

[TommyT]

sorry typo, play not poly.

[Motorhobo]

You said you replaced the tires right after you got it -- does that mean you didn't ride it at all before you got the new tires?

[Laitch]

sorry typo, play not poly.

Thanks. How about the side-to-side movement? What's up with that?

[The Mighty Gryphon]

Laitch, I am probably wrong, but my read of that is that he is talking about the steering head bearings and smooth steering movement.

[Laitch]

Laitch, I am probably wrong

You don't expect me to think that's sincere, do you? :giggles

So by front bearings wally is referring to steering head bearings and by "they" Tommy is referring to the fork. Blood flow has apparently been restored. Fair poly.

[The Mighty Gryphon]

I've been caught out pretty frequently of late.

[Laitch]

I've been caught out pretty frequently of late.

Bad juju, I'm telling you. You should dump that avatar and seek a different personal transformation.

[wally.fisher]

You don't expect me to think that's sincere, do you? :giggles

So by front bearings wally is referring to steering head bearings and by "they" Tommy is referring to the fork. Blood flow has apparently been restored. Fair poly.

Sorry guys, front wheel bearings are just that, they fit into the hub of the wheel rim, head bearings are part of the steering swivel action.
You have had the wheel off a few times now, why not replace the bearings with new, you then can check the head bearings if nothing has changed.


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[Laitch]

Sorry guys, front wheel bearings are just that, they fit into the hub of the wheel rim, head bearings are part of the steering swivel action.

If you'd written wheel it wouldn't have been as much fun translating what you were attempting to convey, wally.  We're all on the same page, although we were anyway. :giggles

[TommyT]

tires - yes, I barely rode the bike before getting new tires. the back tire was 16 years old, the front 13, but both had very little wear, but there was some side rot. I did not think it was safe to ride it with tires like that. Strangle, the bike has 45k miles, 27 years old, by looking at the tires it must have not been ridden much in the last 16 to 13 years.


Front, head bearing, feels smooth side to side.


This hop is light, and I feel it only on smooth roads. The rear shock has 4 positions for damping, I am going to go out an ride soon and try it on all four settings. if it feels like there is NO difference between the settings, I will remove the shock, remove the spring and to see if the shock is dead on damping, but my guess is that it is okay because on the rough roads (and there is a lot of them around here) it would feel very bouncy and so far it does not. Other then this it seems to handle well.

[wally.fisher]

tires - yes, I barely rode the bike before getting new tires. the back tire was 16 years old, the front 13, but both had very little wear, but there was some side rot. I did not think it was safe to ride it with tires like that. Strangle, the bike has 45k miles, 27 years old, by looking at the tires it must have not been ridden much in the last 16 to 13 years.


Front, head bearing, feels smooth side to side.


This hop is light, and I feel it only on smooth roads. The rear shock has 4 positions for damping, I am going to go out an ride soon and try it on all four settings. if it feels like there is NO difference between the settings, I will remove the shock, remove the spring and to see if the shock is dead on damping, but my guess is that it is okay because on the rough roads (and there is a lot of them around here) it would feel very bouncy and so far it does not. Other then this it seems to handle well.

If the bike has been stood so long I suggest you  replace the front fork oil,  old tyres should be replaced. Lotta enjoyable work.


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[TommyT]

I did replace the tires, with new Michelin tires front and rear. I did replace the front fork oil right after the new tires, it did help the overall ride but did not change the hop feeling. It does feel a little soft to me with 5 wt oil, I have some 7.5 wt oil now, I think I will try that, plus the old oil looked crappy, I think another fork oil flush would not hurt.

[wally.fisher]

I did replace the tires, with new Michelin tires front and rear. I did replace the front fork oil right after the new tires, it did help the overall ride but did not change the hop feeling. It does feel a little soft to me with 5 wt oil, I have some 7.5 wt oil now, I think I will try that, plus the old oil looked crappy, I think another fork oil flush would not hurt.

It's more a personal feel ,  some say automatic transmission oil in the forks to be better , some add extra oil, I prefer a 15 wt oil. Trial n error . Are the head bearings good?


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[TommyT]

Yes the head bearings seem good, as far as I can tell. With the front wheel off the ground, movement side to side is smooth and at the stop points on each side I do not feel any looseness or play. When hitting rough spots in the road the front end feels good and solid.


I did ride the bike earlier and tried the different shock rebound settings, it did feel better at the stiffer rebound setting then the softest, but no by much. the two middle settings ( there are 4) did not seem to matter much. If I have to guess, I think the rear shock is mostly spring and not much damping if you know what I mean. Its like seeing a car or truck go by with a bad shock, the wheel is bouncing constantly once it hits one small bump. I am going to take it off and remove the spring to see how easy I can move it. 

[Chaos]

Yup, if that's the original shock it's probably toast.  30-40k was about their limit.

[Motorhobo]

Yup, if that's the original shock it's probably toast.  30-40k was about their limit.

When mine completely failed, it felt like I was riding a hardtail.

I'm not sure you answered the question whether the hopping was there before you changed the tire. If it was not, then you might have a bulging, i.e. manufacturer's defective, tire. A bulge can be balanced out but is still present. Can you remember whether the hopping was present with the original tire?

[wally.fisher]

Yes the head bearings seem good, as far as I can tell. With the front wheel off the ground, movement side to side is smooth and at the stop points on each side I do not feel any looseness or play. When hitting rough spots in the road the front end feels good and solid.


I did ride the bike earlier and tried the different shock rebound settings, it did feel better at the stiffer rebound setting then the softest, but no by much. the two middle settings ( there are 4) did not seem to matter much. If I have to guess, I think the rear shock is mostly spring and not much damping if you know what I mean. Its like seeing a car or truck go by with a bad shock, the wheel is bouncing constantly once it hits one small bump. I am going to take it off and remove the spring to see how easy I can move it.

To check the head bearings, bike off the stand, sit on it  n pull the front brake then rock the bike back and forward, if there is play you will feel it.


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[Laitch]

At 35 to 45 I feel a hop in the front, it is worst around 45 and from there disappears to "almost" smooth over 50 mph.

my guess is that it is okay because on the rough roads (and there is a lot of them around here) it would feel very bouncy and so far it does not. Other then this it seems to handle well.

When my OEM shock wore out, it bottomed out in potholes and was a hard ride in general. Is this hop occurring at predictable intervals within that speed range or is it random?