Need Help Lowkey hopping at low speed

[Requin]

Hello,
I'd like to start by saying that I did do a forum search but the words used came up with no relevant results.
This would be my first naked bike, I was always a cruiser/chopper guy.
I'd like to pick your brains about something I noticed while riding at low speed.
Under 30kmh, but even more so under 15kmh, the bike feels like it's... jumping up and down, very lowkey. Not a wobble, more like a hop, like going over cobblestone but not nearly as bad. Something I never felt on my heavy ass cruisers.

It feels the same in or out of gear, it feels the same with the engine turned off.

Tyres are Michelin road6 GT, new. I used beads to balance the wheels. Wheels are inflated to spec.
Chain is lubed and straight, 4.5 cm slack, every bolt and nut is tight.

Jacked the bike and spun both wheels. No nasty sounds, no side movement, no S shape movement, no bulges, no chips on the rims and also no bends/cracks, both perfect. All 3 disks are also straight, checked that just in case.
The "hop" goes away once I get over 30-ish kmh.
No, it's not a death wobble, I know how those feel.
At high speed the bike rides perfectly. I even tried to induce a death wobble at about 120kmh and it refused to wobble(I know, I'm an idiot).
Anyone got any ideas? I've been riding for 30 years and never felt that... hopping sensation. But my bikes were/are all heavy, with rather soft suspension so... maybe it's just how the road feels on these bikes?
Thanks!

 

[grahammarsden]

I can't tell if that's the OEM rear shock, but have you checked the suspension sag? (Lots of How To videos online)

If you're used to a soft cruiser and this is set up much harder, you'll probably be feeling sensations that you're not used to.

 

[Requin]

I can't tell if that's the OEM rear shock, but have you checked the suspension sag? (Lots of How To videos online)

If you're used to a soft cruiser and this is set up much harder, you'll probably be feeling sensations that you're not used to.

It's OEM, yes. Did not check it but will, I used to do it for my son's dirt bike but never cared about it on my cruisers.
Front feels somewhat stiff, I like it, but the back is rather hard. I'm at 80kg and the rear barely compresses when I sit on it.

 

[Gary in NJ]

Welcome to the forum. Could the problem be a loose front sprocket jumping on the counter-shaft? How do the teeth look on the front sprocket?

 

[Requin]

Welcome to the forum. Could the problem be a loose front sprocket jumping on the counter-shaft?

Thank you.
Would that not create a lot of issues at high speed? Or when launching the bike? I beat the hell out of it today, nothing felt strange. Pulls great, launches great.
If the sprocket would jump, it should feel like a... slipping clutch, more or less. Would it not?

 

[Motogiro]

Welcome to the forum!
When I bought my FZ6 new, it had the stock Bridgestone tires from the factory. At low speed I would noticed a feeling at low speed. On examination of the front tire, it turned out to be cupping on the tread. Replaced the tires and all was good.

 

[Requin]

Welcome to the forum!
When I bought my FZ6 new, it had the stock Bridgestone tires from the factory. At low speed I would noticed a feeling at low speed. On examination of the front tire, it turned out to be cupping on the tread. Replaced the tires and all was good.

Thank you.
Will take them off and check.

 

[grahammarsden]

Thank you.
Will take them off and check.

Have a look at the DOT number on the side.

First two numbers are the week of manufacture, second two are the year, so 0126 would mean they were made in the first week of this year. Just because they're "new" on, doesn't mean they're actually new tyres!

 

[Gary in NJ]

I would expect an out of spec or unbalanced tire to get worse with speed, not better.

 

[Requin]

Have a look at the DOT number on the side.

First two numbers are the week of manufacture, second two are the year, so 0126 would mean they were made in the first week of this year. Just because they're "new" on, doesn't mean they're actually new tyres!

Yeah, I know. They were made in 2025. Checked when they got here as the website failed to mention when they were made.

 

[Requin]

I would expect an out of spec or unbalanced tire to get worse with speed, not better.

Indeed. But I checked them anyway since I have no frikin clue what it could be that's giving me the bunny feeling. But I am now 90% sure it's just how these bikes feel since nothing seems to be out of order...

 

[tuning-forks]

You are right at the minimum for chain slack. These bikes are known to be quite picky about that. It's at least worth a try with a bit more slack. I think from what I've read here the usual recommendation is 2 inch (5 cm).

 

[Requin]

You are right at the minimum for chain slack. These bikes are known to be quite picky about that. It's at least worth a try with a bit more slack. I think from what I've read here the usual recommendation is 2 inch (5 cm).

Manual said 4.5-5.5 cm. So I went with 4.5. But I can bump it to 5 and test.

 

[TownsendsFJR1300]

2" exactly at it's tightest point, well lubricated. You will feel, not good, 1.75". Looser than 2",
shifting will be sloppy.

What is the condition / mileage of the chain and sprockets? You could very well have some kinks in there
if the PO neglected it.

If, say at 30 MPH, steady light throttle, (2nd or 3rd gear), the chain should be SMOOTHLY running around the sprockets.

What your describing is NOT normal for the bike..

I would also, just for S&G's, remove both wheels and feel the bearings, by hand for smoothness, turning.
It would take that long to rule them out. With the rear off, you can further check the chain, link by link,
for NO BINDING...

Lastly, is there any excessive brake drag? The newer S2 front brakes, the original seals, like to NOT release
and will grab the rotor. You should be able to free spin the ft, by hand, easily 2 full rotations...

.

 

[Requin]

2" exactly at it's tightest point, well lubricated. You will feel, not good, 1.75". Looser than 2",
shifting will be sloppy.

What is the condition / mileage of the chain and sprockets? You could very well have some kinks in there
if the PO neglected it.

If, say at 30 MPH, steady light throttle, (2nd or 3rd gear), the chain should be SMOOTHLY running around the sprockets.

What your describing is NOT normal for the bike..

I would also, just for S&G's, remove both wheels and feel the bearings, by hand for smoothness, turning.
It would take that long to rule them out. With the rear off, you can further check the chain, link by link,
for NO BINDING...

Lastly, is there any excessive brake drag? The newer S2 front brakes, the original seals, like to NOT release
and will grab the rotor. You should be able to free spin the ft, by hand, easily 2 full rotations...

.

Checked both wheels/tyres/sprockets/chain/bearings and brakes. Nothing if out of order.
Also gave the chain 5cm of slack, from 4.5 where I set it.
Nothing has changed, bike "hops" the same way.

 

[Gary in NJ]

Bad (or destroyed) wheel bearing?

Frozen brake caliper?

Blown shock seal?

Could be anything…you’re gonna have to dig a little deeper.

 

[TownsendsFJR1300]

Bad (or destroyed) wheel bearing?

Frozen brake caliper?

Blown shock seal?

Could be anything…you’re gonna have to dig a little deeper.

Yup, what's described is definitly not normal...

May want to try the string alignment method between the wheels, perhaps a bent frame, something tweeked.
Make sure both wheels are aligned....

.

 

[Requin]

Bad (or destroyed) wheel bearing?

Frozen brake caliper?

Blown shock seal?

Could be anything…you’re gonna have to dig a little deeper.

Checked all of the above, all fine.

 

[Requin]

Yup, what's described is definitly not normal...

May want to try the string alignment method between the wheels, perhaps a bent frame, something tweeked.
Make sure both wheels are aligned....

.

Wouldn't a bent frame or unalinged wheels create nasty problems at high speed?
Bike glides once I get over 30-ish.
Pushed it to 180 and nothing was off about it. I even did wheelies to see how the front sus takes the drop. Nothing felt out of order.
But I will check on those also as I am out of things to check anyway.

 

[grahammarsden]

Try taking it up to eg 50kmh on a straight, smooth piece of road, then throttle off, put it in neutral and let it slow down naturally.

Loosen your grip on the bars until you're only just holding them, but with almost no pressure.

When the sensation starts, are you feeling it through the bars or your backside?

Try it again with your thighs gripping the tank so your back is straight, core engaged and your feet are pressing down on the pegs.

Does that change the feeling?