HPRE

Menu

Members Rides

My 2000


in
Members Rides

72 Guests, 4 Users
GSS, gremlin, retrolynn, burtial
Welcome, Guest. Please login or register.
Did you miss your activation email?
July 30, 2014, 02:57:14 AM

Login with username, password and session length

 

Author Topic: Bouncing front end  (Read 733 times)

boggy

  • Grand Gearhead
  • *****
  • Posts: 1756
  • Karma: 0
  • Karma Ultra: 7
Bouncing front end
« on: August 25, 2013, 12:39:14 AM »
I get more of a bounce, than the usual vibes over 25mph.  Just started happening. My new K70s/3.5 were really low all early Summer and I just set them to 24F/28R.  I need to get a proper tire gauge to double check as I don't trust the gas station gauge or my Cruz tool gauge so that is my first order of business.  However I also just fixed a leaking fork oil drain bolt and both sides have fresh ATF-F (I had it in there before with no bounce). 

Any ideas on tires vs forks?  I put in 200ml as I did before.  2007 AVL.

Thanks. Boggy

PS if you have a tire gauge you trust let me know what kind.
2007 AVL
2006 DRZ400SM

greenie

  • Scooter
  • **
  • Posts: 60
  • Karma: 0
Re: Bouncing front end
« Reply #1 on: August 25, 2013, 03:22:24 AM »
FWIW i'm using an older craftsman digital gauge and i do trust it.
did you possibly throw a wheel weight?  good luck
95 ural tourist w/ 97 motor (650)
06 electra

Buckeroo

  • Bulleteer
  • ***
  • Posts: 102
  • Karma: 0
Re: Bouncing front end
« Reply #2 on: August 25, 2013, 02:55:05 PM »
Sounds like your front wheel is out of balance.
This bike was stored for 3.5 years.  It had fallen on its side for awhile. I claimed it about a year and a half ago. Thus the low miles and inexperienced owner.
2008 Bullet Electra Classic 500
Classic Frame and AVL motor
Electric Start
Electronic Ignition
5 speed
CV Carb

D the D

  • Grand Gearhead
  • *****
  • Posts: 1174
  • Karma: 0
Re: Bouncing front end
« Reply #3 on: August 25, 2013, 04:36:47 PM »
Sounds like your front wheel is out of balance.

+1  Take them off and get them balanced.  My Triumph dealer mechs will do it for a 12 pack of Mountain Dew and the price of any spoke weights they use.  Use the spoke weights, not the stick-ons.  Stick-ons tend to get thrown to the wind.
Get a dial gauge or digital gauge from the autoparts store.  Any but the cheapest is better than the gauges on the gas station pumps that people throw to the ground all the time.
Accuracy of + or - one lb doesn't really matter.  Once you have a reading that runs well for you, say 24/28 or 26/30, just use the same gauge all the time.  You want to maintain the same setting and eliminate the variable accuracy of using random gauges.
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH

boggy

  • Grand Gearhead
  • *****
  • Posts: 1756
  • Karma: 0
  • Karma Ultra: 7
Re: Bouncing front end
« Reply #4 on: August 28, 2013, 02:35:36 PM »
OK - sounds like the consensus is balance issue.  I definitely did not lose a front weight so I'm not sure how it went out of balance. However, I did so much fork work this Spring/Summer I may have been focusing on the them during my rides (plus there is hardly a smooth road around here).

Just wanted to double check this wasn't a tell tale sign of tire pressure/fork oil issues. Thanks for the feedback.

Boggy
2007 AVL
2006 DRZ400SM

High On Octane

  • Grand Gearhead
  • *****
  • Posts: 3574
  • Karma: 0
  • Go Fast & Look Good Doing It
Re: Bouncing front end
« Reply #5 on: August 28, 2013, 02:49:41 PM »
If you hit any big pot holes you may have bent your wheel which would make it feel out of balance.

Scottie
Bulldog Kustoms - Denver, CO
Specializing In Kustom Paint

The Blackhawk
1958 Enfield/Indian 711cc Twin

Building the 1st EVER Supercharged RE Twin
FULL RACE motor with ACE Performance

DanKearney

  • Bulleteer
  • ***
  • Posts: 232
  • Karma: 0
Re: Bouncing front end
« Reply #6 on: August 28, 2013, 06:57:59 PM »
If you're going to go for a re-balance, I suggest you consider using Dynabeads instead of traditional wheel weights.  I've found them to work much better than weights on all three of my bikes.  2oz in each tube seems to work best.

Cheers,

Dan K.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Dan Kearney - Black Hawk, Colorado, USA
Royal Enfield Bullet Classic, Yamaha XT225, Ural Gear Up, BMW R100R
http://dansmotorcycleblog.blogspot.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

KB8ANY

  • Scooter
  • **
  • Posts: 85
  • Karma: 0
Re: Bouncing front end
« Reply #7 on: August 29, 2013, 06:23:06 PM »
I had the same problem early on, and in addition a "clank" when the fork would drop off of something (like the lip of a pothole) without first being compressed.

Also, on my bike, the 200ml did not give the level called out in the shop manual.  The shop manual calls out sticking a 1/4 inch rod down into the fork, with a resulting level of 370mm to 380mm.  With 200ml the level was too low.

I cured both by putting in 240 - 250 ml.

I also get a better ride with ordinary 10W-30 oil, also called out by the shop manual.

Good luck.

Paul

classicrider

  • Neophyte
  • *
  • Posts: 20
  • Karma: 0
Re: Bouncing front end
« Reply #8 on: August 30, 2013, 10:00:16 AM »
Seriously i can't work out the logic in using ATF-F in front forks.It's great in certain bike clutch's,but front forks need the slipperiest lube you can buy.It's all about reducing friction on seals and bushes.
Using an oil with high friction will only create bounce by resisting movement until a point is reached,and this energy will release all of a sudden.Hard on the wrists.My bet is this is the cause.
 

D the D

  • Grand Gearhead
  • *****
  • Posts: 1174
  • Karma: 0
Re: Bouncing front end
« Reply #9 on: August 30, 2013, 02:12:44 PM »
Seriously i can't work out the logic in using ATF-F in front forks.It's great in certain bike clutch's,but front forks need the slipperiest lube you can buy.It's all about reducing friction on seals and bushes.
Using an oil with high friction will only create bounce by resisting movement until a point is reached,and this energy will release all of a sudden.Hard on the wrists.My bet is this is the cause.

"Stiction"
ATF is the snake oil of choice for bikers.  Fork Oil is designed to reduce "Stiction", ATF is designed to, uh, run in an automatic transmission.
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH

boggy

  • Grand Gearhead
  • *****
  • Posts: 1756
  • Karma: 0
  • Karma Ultra: 7
Re: Bouncing front end
« Reply #10 on: August 30, 2013, 02:19:06 PM »
I had the same problem early on...
With 200ml the level was too low.
I cured both by putting in 240 - 250 ml.

That is very interesting. I was under the impression 200mm was tip top tight but I didn't check.  OK... very good to know.

Seriously i can't work out the logic in using ATF-F in front forks.It's great in certain bike clutch's,but front forks need the slipperiest lube you can buy. My bet is this is the cause.
 

OK.  Well this is a VERY easy thing for me to try.  I did just put the ATF in this Spring so you may be on to something.  It seemed like guy have been using ATF in their forks forever so I figured "old bike design - old bike logic," but maybe that's not serving me best in this case. 

I've heard people use 5w, 10w, and 15w fork oil so maybe I'll start in the middle at 10.

ATF is the snake oil of choice for bikers.

Haha.  Awesome.

Ok... thanks guys.  Good stuff.  Appreciate the info.

Boggy
2007 AVL
2006 DRZ400SM

D the D

  • Grand Gearhead
  • *****
  • Posts: 1174
  • Karma: 0
Re: Bouncing front end
« Reply #11 on: August 30, 2013, 02:27:08 PM »
Oh, and some people won't admit this, but they use ATF 'cause they're just too cheap to buy the right stuff.
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH

KB8ANY

  • Scooter
  • **
  • Posts: 85
  • Karma: 0
Re: Bouncing front end
« Reply #12 on: August 30, 2013, 03:01:12 PM »
That is very interesting. I was under the impression 200mm was tip top tight but I didn't check.  OK... very good to know.

OK.  Well this is a VERY easy thing for me to try.  I did just put the ATF in this Spring so you may be on to something.  It seemed like guy have been using ATF in their forks forever so I figured "old bike design - old bike logic," but maybe that's not serving me best in this case. 

I've heard people use 5w, 10w, and 15w fork oil so maybe I'll start in the middle at 10.

Haha.  Awesome.

Ok... thanks guys.  Good stuff.  Appreciate the info.

Boggy:

I only offer the 240ml trick because that's what I found on my bike.  I have been around long enough to not be surprised when I find that components don't match up with manufacturing runs.  A 1/4" dowel from Ace Hardware is an inexpensive checking tool.

Good luck.

Paul

Boggy

barenekd

  • Grand Gearhead
  • *****
  • Posts: 5038
  • Karma: 0
Re: Bouncing front end
« Reply #13 on: August 30, 2013, 09:10:56 PM »
The book actually calls for 265 ml of oil in your forks. the 200 ml or so comes from never knowing how much you got out when you drained the sludge. If you have already changed the oil with something that will actually run out, (which you did), that could have washed the sludge away, and now you can actually change all the oil. But gotta go with the fork oil argment. it is actually made for forks! Some old wives tales never die! As for causing the shaking, my bet would be that your tire is out of round for setting so long. Try about 40psi in it, ride it awhile, and see if that will round it out again. Also when you reset your pressure again, use less air, like about 18 psi Front and 24 rear. You'll have a lot smoother ride and have the air pressure down to the recommendations.
Bare
2013 Moto Guzzi V7 Racer
2011 Black Classic G5 (RIP)
I refuse to tiptoe through life only to arrive safely at death
http://www.controllineplans.com

boggy

  • Grand Gearhead
  • *****
  • Posts: 1756
  • Karma: 0
  • Karma Ultra: 7
Re: Bouncing front end
« Reply #14 on: August 31, 2013, 05:34:22 PM »
Where the heck did I get 200ml from?  OK, I should definitely try putting in the correct amount. I don't have an AVL shop manual... just the Snidal which I'm not 100% sure covers the AVL's fork-fill limit.  I'll also get some proper fork oil.  Changing the oil is fast although you'd be surprised how hard it is to find crush washers around here.  Only the Ducati-Triumph shop had what I needed and they were 3 bucks per for "Yamaha" brand washers.  Glad now I bought extras.

I'll definitely try that air pressure trick.  I never thought about it but yeah... it sat for a few months this Spring while the weather went from cold and rainy to way to effing hot to gear up.

Thanks.
2007 AVL
2006 DRZ400SM

barenekd

  • Grand Gearhead
  • *****
  • Posts: 5038
  • Karma: 0
Re: Bouncing front end
« Reply #15 on: August 31, 2013, 06:34:09 PM »
You guys need to look at Aircraft Spruce and Specialties for weird washers and seals, like the exhaust gaskets and other strange items that motorcycle shops charge an arm and leg for.
You may have gotten the 200 ml from me because that's what I put in my G5 forks, but it was because I didn't know how much glop I still had in the forks, and the 200ml worded quite nicely for me so I never bothered to try actually filling the forks up any more. It ws basically a start off number and see how it worked.
It was easy enough to add more if it felt like I needed it. Some people had been complaining that the 265 was too much, but there again how much glop was still in the forks? Since you had already changed the oil, it probably helped flush all the old crap out.
Bare
2013 Moto Guzzi V7 Racer
2011 Black Classic G5 (RIP)
I refuse to tiptoe through life only to arrive safely at death
http://www.controllineplans.com

D the D

  • Grand Gearhead
  • *****
  • Posts: 1174
  • Karma: 0
Re: Bouncing front end
« Reply #16 on: August 31, 2013, 09:05:23 PM »
...You may have gotten the 200 ml from me because that's what I put in my G5 forks, but it was because I didn't know how much glop I still had in the forks, and the 200ml worded quite nicely for me so I never bothered to try actually filling the forks up any more....

FWIW Bare, I put in 200ml via syringe into each fork and measured with a rod, per the manual, just wet on the end when touching the spring retainer inside.  200ml was the perfect amount.
Quoting Snidal's Manual: "Feel for the spring retainer at the top of the valve stud (the bottom of the spring). This is the minimum oil level."
I assume that won't work with the newer upside-down forks.
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH

barenekd

  • Grand Gearhead
  • *****
  • Posts: 5038
  • Karma: 0
Re: Bouncing front end
« Reply #17 on: September 04, 2013, 10:12:34 PM »
What's got new upside down forks?
I thought the AVLs had the same forks as the G5--My bad!
Bare
« Last Edit: September 04, 2013, 10:15:18 PM by barenekd »
2013 Moto Guzzi V7 Racer
2011 Black Classic G5 (RIP)
I refuse to tiptoe through life only to arrive safely at death
http://www.controllineplans.com

D the D

  • Grand Gearhead
  • *****
  • Posts: 1174
  • Karma: 0
Re: Bouncing front end
« Reply #18 on: September 05, 2013, 03:27:32 AM »
You're right Bare.  That was just for those who have upside down ones before they try.
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH

boggy

  • Grand Gearhead
  • *****
  • Posts: 1756
  • Karma: 0
  • Karma Ultra: 7
Re: Bouncing front end
« Reply #19 on: September 12, 2013, 08:38:41 PM »
Hey where does "265ml" come from? I have the Snidal manual and I see it calling for 200ml.  I don't have an AVL shop manual - is that where it is?
2007 AVL
2006 DRZ400SM