Front tire "bounce" at speed

Kipper1012 · 05-03-2017, 11:17 PM

Hey guys I have this weird front tire hop at 40mph and above.
I thought it might be the front wheel out of Ballance so I took it off and had the local shop ballance it. Remounted it and well ..,... it's still doing it

Any ideas guys ?

jct842 · 05-03-2017, 11:49 PM

Out of round and still In balance.

Megadan · 05-04-2017, 12:10 AM

Out of round, or off center. Get the front wheel off the ground, mount a pencil or other small stick like object to the fork with wire or zip ties so it doesn't move, and put it somewhat close to the outer edge of the rim. If the edge of the rim moves up and down from that point, and/or side to side aka away and near to it, then your wheel is out of true and that needs to be taken care of.

Adjuster · 05-04-2017, 12:11 AM

Lean forward. The wind is catching your chest. More body weight on the front tire.

/

pete · 05-04-2017, 12:17 AM

dose it still have the chinese tyre on it ?
When you say "HOP".. hop to me means
the tyre leaves the ground

.

rwl6935 · 05-04-2017, 07:58 AM

Tire could have a flat spot on it

Sullybiker · 05-04-2017, 09:34 AM

I have this on my TT250, it's actually always been there, but became greater in amplitude when the tyre wore down.

I thought I had a warped rotor that was grabbing, but when I lifted the front wheel I realised it was the tyre. It only happens between 35-40 mph.

First, check your rim is true. They're big clunky steel things and it's unlikely that it's gone out of true, but good to rule it out, right? Get some large zip ties, or anything you can fasten to the bike to make a crude pointer (a little screwdriver zip-tied on also works, but I use the pointy end of the ziptie itself) place the tip of your improvised pointer near the rim, not quite touching. Sight along the rim (I kneel at the front of the bike and sight in on the gap between the fork leg and the wheel, where I fix my ziptie) spin the wheel and you'll soon see any deviation from true (runout).

My rim was fine, it had a tiny bit of lateral runout (side wobble) and no radial runout (up and down wobble) that I could see at all. I placed a wooden block under the tyre, again not quite touching, (you can use a book, anything you can choose from various thicknesses) and could clearly see the front tyre was out of round as it spun above the block.

There's a rubber ridge on the tyre bead that runs around all the way around the tyre, and in my case it was clear that it was slightly higher at one point relative to the rim, as if the tyre was slighty big for the rim and it had bulged out at that point.

The tyre is nearly done anyway, so I'm leaving it for a few days. In the meantime I deflated the tyre, massaged the bead with my hand (ooh err!) and put a little tyre oil on there, I then inflated the tyre slowly to 1.5 times the recommended pressure (around 45-50 psi), Let it sit for a minute, then deflated the tyre to the correct pressure. This was to encourage the tyre to reseat, although if it has deformed (mine has) it will only do so much. It's helped and has reduced the wheel hop to what it was when the bike was new, I can live with it until I throw a new tyre on.

If you do some googling, you'll learn that inexpensive dual sport tyres tend to have quite iffy quality control, they're usually difficult to balance. I don't mind so much on a bike that rarely sees more than 50mph.

Kipper1012 · 05-04-2017, 01:35 PM

Quote:

Originally Posted by pete

dose it still have the chinese tyre on it ?
When you say "HOP".. hop to me means
the tyre leaves the ground

.

It's not leaving the ground but you can definitely see the up and down movement of the forks that coincides to what i am feeling.
Yes still has Chinese tires that came with it only has 150mi on it

I will check that the Rim is true when I get home tonight

JeremyC · 05-04-2017, 03:52 PM

Have you checked the fork oil levels? Maybe one is nearly empty and causing dampening issues that is making it even worse. My front wheel was way out laterally, so check your wheel to make sure it's true.

chuck · 05-04-2017, 04:06 PM

Quote:

Originally Posted by Kipper1012

Hey guys I have this weird front tire hop at 40mph and above.
I thought it might be the front wheel out of Ballance so I took it off and had the local shop ballance it. Remounted it and well ..,... it's still doing it

Any ideas guys ?

There's not much riding on that front especially at higher speeds,I notice it on mine too when I'm going at 60 and up but the bike feels stable and that's what matters.

Kipper1012 · 05-04-2017, 04:13 PM

Quote:

Originally Posted by JeremyC

Have you checked the fork oil levels? Maybe one is nearly empty and causing dampening issues that is making it even worse. My front wheel was way out laterally, so check your wheel to make sure it's true.

I have not checked the oil levels but when I put it together 150mi ago I drained the stock oil and put in 250ml of good quality fork oil and there are no signs of leaking .
When I get home from work I am going to check to make sure the wheel is true

Quote:

Originally Posted by chuck

There's not much riding on that front especially at higher speeds,I notice it on mine too when I'm going at 60 and up but the bike feels stable and that's what matters.

yes the bike feels very stable but when i get up to 60 the hop turns into an annoying vibration

MOTOXtreme · 05-04-2017, 06:44 PM

Quote:

Originally Posted by Sullybiker

...There's a rubber ridge on the tyre bead that runs around all the way around the tyre, and in my case it was clear that it was slightly higher at one point relative to the rim, as if the tyre was slighty big for the rim and it had bulged out at that point.

Ive had this several times. So much so that I SLOWLY air the tire and bounce it while spinning it during the air up process. Hope that makes since. After I have bounced / aired the tire it seems to fit the rim evenly.

Not at all sure if this is your issue but pay close attention to the bead all the way around the tire on both sides.

**Mine still seems to have a slight hop / vibration at a certain speed but its very manageable.

chuck · 05-04-2017, 06:50 PM

Quote:

Originally Posted by Kipper1012

I have not checked the oil levels but when I put it together 150mi ago I drained the stock oil and put in 250ml of good quality fork oil and there are no signs of leaking .
When I get home from work I am going to check to make sure the wheel is true

yes the bike feels very stable but when i get up to 60 the hop turns into an annoying vibration

That is a lot of oil I don't think you should exceed 180ml in each fork.

Kipper1012 · 05-04-2017, 09:16 PM

Lol. That's what I meant 150ml

MOTOXtreme · 05-04-2017, 09:29 PM

Really?? That don't sound right to me. I got right around 225ml (dang near 1 cup) out of each fork. I put that back in as well and my bike rides great on road and off. I'd double check the the oil requirements.

05-03-2017, 11:17 PM	#1
Kipper1012 Join Date: Mar 2017 Location: Florida Posts: 198	Front tire "bounce" at speed Hey guys I have this weird front tire hop at 40mph and above. I thought it might be the front wheel out of Ballance so I took it off and had the local shop ballance it. Remounted it and well ..,... it's still doing it Any ideas guys ? __________________ 2016 Green Bashan Brozz.
	0

05-04-2017, 12:17 AM	#5
pete Join Date: Jan 2012 Location: ChCh , NZ Posts: 2,261	dose it still have the chinese tyre on it ? When you say "HOP".. hop to me means the tyre leaves the ground . __________________ 09 XT660R ... 06 TTR250 ... 80 Montesa H6 125 Enduro... 77 Montesa Cota 348 MRR "Malcom Rathnell Replica"... Current resto projects.. 81 Honda CT110... 80 Kawasaki KL250A1... 11 Husaburg TE125 enduro... "sold" along with another 31... Lifan 125 Pitbike.. "stolen" ... KIWI BIKER FORUM...... http://www.kiwibiker.co.nz/forums/content.php All the best offroad rides in NZ... http://www.remotemoto.com/ E-mail... xtpete1@gmail.com
	0

05-04-2017, 09:16 PM	#14
Kipper1012 Join Date: Mar 2017 Location: Florida Posts: 198	Lol. That's what I meant 150ml __________________ 2016 Green Bashan Brozz.
	1

05-04-2017, 09:29 PM	#15
MOTOXtreme Join Date: Apr 2007 Location: Waynesboro, Virginia Posts: 336	Really?? That don't sound right to me. I got right around 225ml (dang near 1 cup) out of each fork. I put that back in as well and my bike rides great on road and off. I'd double check the the oil requirements. __________________ Brian Previously owned / operated MOTO Xtreme selling American Lifan / Check out my friends at www.armattanquads.com "Imagination is more important that knowledge" Albert Einstein
	0

05-03-2017, 11:49 PM	#2
jct842 Join Date: Jan 2015 Location: arkansas Posts: 297	Out of round and still In balance.
	0

05-04-2017, 12:10 AM	#3
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 7,986	Out of round, or off center. Get the front wheel off the ground, mount a pencil or other small stick like object to the fork with wire or zip ties so it doesn't move, and put it somewhat close to the outer edge of the rim. If the edge of the rim moves up and down from that point, and/or side to side aka away and near to it, then your wheel is out of true and that needs to be taken care of.
	0

05-04-2017, 12:11 AM	#4
Adjuster Join Date: Dec 2014 Location: Deerfield Beach FL Posts: 1,410	Lean forward. The wind is catching your chest. More body weight on the front tire. /
	0

05-04-2017, 07:58 AM	#6
rwl6935 Join Date: Mar 2017 Posts: 203	Tire could have a flat spot on it
	0

05-04-2017, 09:34 AM	#7
Sullybiker Join Date: Dec 2016 Location: Western PA Posts: 363	I have this on my TT250, it's actually always been there, but became greater in amplitude when the tyre wore down. I thought I had a warped rotor that was grabbing, but when I lifted the front wheel I realised it was the tyre. It only happens between 35-40 mph. First, check your rim is true. They're big clunky steel things and it's unlikely that it's gone out of true, but good to rule it out, right? Get some large zip ties, or anything you can fasten to the bike to make a crude pointer (a little screwdriver zip-tied on also works, but I use the pointy end of the ziptie itself) place the tip of your improvised pointer near the rim, not quite touching. Sight along the rim (I kneel at the front of the bike and sight in on the gap between the fork leg and the wheel, where I fix my ziptie) spin the wheel and you'll soon see any deviation from true (runout). My rim was fine, it had a tiny bit of lateral runout (side wobble) and no radial runout (up and down wobble) that I could see at all. I placed a wooden block under the tyre, again not quite touching, (you can use a book, anything you can choose from various thicknesses) and could clearly see the front tyre was out of round as it spun above the block. There's a rubber ridge on the tyre bead that runs around all the way around the tyre, and in my case it was clear that it was slightly higher at one point relative to the rim, as if the tyre was slighty big for the rim and it had bulged out at that point. The tyre is nearly done anyway, so I'm leaving it for a few days. In the meantime I deflated the tyre, massaged the bead with my hand (ooh err!) and put a little tyre oil on there, I then inflated the tyre slowly to 1.5 times the recommended pressure (around 45-50 psi), Let it sit for a minute, then deflated the tyre to the correct pressure. This was to encourage the tyre to reseat, although if it has deformed (mine has) it will only do so much. It's helped and has reduced the wheel hop to what it was when the bike was new, I can live with it until I throw a new tyre on. If you do some googling, you'll learn that inexpensive dual sport tyres tend to have quite iffy quality control, they're usually difficult to balance. I don't mind so much on a bike that rarely sees more than 50mph.
	2

05-04-2017, 03:52 PM	#9
JeremyC Join Date: Apr 2017 Location: Southern IL Posts: 132	Have you checked the fork oil levels? Maybe one is nearly empty and causing dampening issues that is making it even worse. My front wheel was way out laterally, so check your wheel to make sure it's true.
	1