Author Topic: Fork leak when bike is sitting  (Read 1401 times)

0 Members and 1 Guest are viewing this topic.

Online MAN OF BLUES

  • I Need a Life
  • ******
  • Posts: 6944
  • AREA: North Central Area
  • COG#: 5977
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #25 on: July 24, 2017, 08:14:51 pm »
 :P

And to go back and clarify, my comment about the effects of the airspace were made to dispell so what, this post below, or some of it anyways...

With the correct amount of oil in the forks, to allow the dampers to do what they are supposed to do, and the normal airspace above to allow the forks to compress said airspace to half of its volumn by design, increasing that airspace has no effect on the correct fork damping....
I'll use this as an example:
Take a set of forks, all stock guts, springs, and oil level, and add a 2 foot extension tube to the top, and also add a 2 foot spacer to compensate, and keep the contact with the springs....all this is sealed airtight, as the factory fork caps do. No additional air pressure....
Will the forks ceasse to function? Will they bottom out?
No. They won't. This is what I meant when I described the tests I did, on pre 94 forks, fitted with progressive springs, and left unsealed, and also added a pressure gauge to the schrader valve.... I thought that part was clearly written, and could be digested... I guess it was not.

I'll also add that for these tests I did, on a smooth road, I placed 4 pieces of 2 x 4 on the road, spaced about 20' apart, and rode over these at about 8-10 mph.
I wanted to test travel, and did so by putting tie wraps on both fork tubes, slid down against the dust seal, so I could measure the compression distances.
Ran this test 3 times, 3 different scenarios, as noted originally.
Scrader valve in, no pressure, sealed forks.
Schrader valve out, open forks.
Plastic cap with .030" hole on open Schrader valve.
Solid plastic cap threaded on open Schrader valve 1-1/2 turns (apprx 2 threads, to see if it would "pop" off)
Low pressure dial faced air gauge attached to open schrader valve fitting.

The difference in the tie wrap locations were at max 1/8", and I have to say that could have been caused by braking or getting off the bike... moot.
All were right about the 3" mark +/- 1/8"
The 15 psi full face dial gauge never jumped above 2 psi, and when I screwed that same gauge on the other forks "fake" threaded fitting, did the same, so I attribute the reading to simply the needle bouncing from shock.

The oil shocks suck to begin with and I don't need it.

 :-\

The oil and mechanical spring work together to supprt the bike, as well as provide dampening. Without the oil, there would be a much larger volume of air in the fork, which would allow the bike to bottom out more frequently. The spring by itself is not strong enough, it relies on the compression of the air in the fork to prevent bottoming.
« Last Edit: July 24, 2017, 08:39:49 pm by MAN OF BLUES »

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW

Offline Steve in Sunny Fla

  • Industry Member
  • I Need a Life
  • *
  • Posts: 7360
  • AREA: Southeast Area
  • COG#: 6977
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #26 on: July 24, 2017, 08:57:16 pm »
M OB, I knew you'ld know it, that's why you paid the big bucks  ;)

 But isn't the air , being at atmospheric,  14.7 psi at sea level, so doubled would be 29.4 psi? Steve
C-14 ECU flashing for performance and rideability enhancement
C-10 Carb work , cams, & performance enhancements
 " Modifications for sport-tourers, BY a sport-tourer"
https://sites.google.com/site/shoodabenengineering/home

Online MAN OF BLUES

  • I Need a Life
  • ******
  • Posts: 6944
  • AREA: North Central Area
  • COG#: 5977
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #27 on: July 24, 2017, 09:04:16 pm »
M OB, I knew you'ld know it, that's why you paid the big bucks  ;)

 But isn't the air , being at atmospheric,  14.7 psi at sea level, so doubled would be 29.4 psi? Steve

You hoser... :rotflmao:

Go pick up your air gauge, and read it.....
Does it read 14.7 or zero. :nananana: :))

I did mention riding to the top of a mountain, or at sea level... what is the weight of an unladen sparrow????

Also, I went to see the rates on sonic springs...
The hefty ones you and I would use, are 1.2 kg/mm...

That works out to a spring force of 185.2 pounds at half compression, and 370 pounds at full compression.....

I don't think air is a factor anymore... :rotflmao: :rotflmao: :rotflmao: :rotflmao:
Ya just need some "airspace" as specified. :great: :great:

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW

Offline Steve in Sunny Fla

  • Industry Member
  • I Need a Life
  • *
  • Posts: 7360
  • AREA: Southeast Area
  • COG#: 6977
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #28 on: July 24, 2017, 09:19:05 pm »
well, if atmospheric is zero, the if you compress the air to 1/2 the area then the pressure is 2x0?  ::)

  No seriously, I related the story, and with 1/2 the air that was supposed to be in the forks they were almost solid. Seriously unridable.

Sounds like fodder for a great experiment... for you :rotflmao: :rotflmao: :rotflmao: :nananana: :beerchug:  Steve
C-14 ECU flashing for performance and rideability enhancement
C-10 Carb work , cams, & performance enhancements
 " Modifications for sport-tourers, BY a sport-tourer"
https://sites.google.com/site/shoodabenengineering/home

Online MAN OF BLUES

  • I Need a Life
  • ******
  • Posts: 6944
  • AREA: North Central Area
  • COG#: 5977
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #29 on: July 24, 2017, 09:34:08 pm »
well, if atmospheric is zero, the if you compress the air to 1/2 the area then the pressure is 2x0?  ::)

  No seriously, I related the story, and with 1/2 the air that was supposed to be in the forks they were almost solid. Seriously unridable.

Sounds like fodder for a great experiment... for you :rotflmao: :rotflmao: :rotflmao: :nananana: :beerchug:  Steve

I don't dispute that, I corroborate it in fact...
When I did the calcs based on specs, and you had 150 mm extended, when you compress them they went solid.... no question there bro,
Surprised you didn't blow a seal, ....speaking of jokes like that, I just love you guys.... and love to poke fun, especially at Ted, because he gets all like..."man, now you're making fun of me and hurt my feelings... :'(   "  but in reality he knows we care about him.....
Hey, let's get Ted to do the experiment... yeah, that's the ticket..... "hey, Ted, ......." :rotflmao: :great: :great: :beerchug:

Besides, even tho you don't drink, and I can't drink anymore, he can, and that will chase away allllll the silly things we say... :beerchug:


30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW

Offline Steve in Sunny Fla

  • Industry Member
  • I Need a Life
  • *
  • Posts: 7360
  • AREA: Southeast Area
  • COG#: 6977
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #30 on: July 24, 2017, 09:56:35 pm »
Poor Ted, everyone picks on him. At least he doesn't wear stretch pants that I know of!  :rotflmao: :rotflmao: :rotflmao: :rotflmao: :rotflmao: :rotflmao:

Steve
C-14 ECU flashing for performance and rideability enhancement
C-10 Carb work , cams, & performance enhancements
 " Modifications for sport-tourers, BY a sport-tourer"
https://sites.google.com/site/shoodabenengineering/home

Offline VTconnie

  • Crotch Rocket
  • ****
  • Posts: 1550
  • AREA: Northeast Area
  • COG#: 11081
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #31 on: July 24, 2017, 10:42:03 pm »
Poor Ted, everyone picks on him. At least he doesn't wear stretch pants that I know of!  :rotflmao: :rotflmao: :rotflmao: :rotflmao: :rotflmao: :rotflmao:

Steve

Yeah and at least doesn't suggest just draining some oil out of something leaking. If DC gets an engine oil leak, just drain a little out? No one even mentioned how having uneven oil levels in the shocks would have worked out on the road, either. This whole thread blows my mind..
<--2003 Concours C-10 "Conifer", -AKA- The Cruise Missile
1980 CB900C DOHC "Old Iron" -AKA- The Hill Climber                

Offline connie_rider

  • OtP {assistant} Slave Labor
  • I Need a Life
  • ******
  • Posts: 7190
  • Help us make "OtP" possible! "AGAIN"
  • AREA: South Central Area
  • COG#: 4154
  • Membership Level: Asst. Area Director
Re: Fork leak when bike is sitting
« Reply #32 on: July 25, 2017, 01:18:04 am »
Ya'll are picking on me again.   :-[

Replying to a few key points ya'll mentioned.
* Steve's right it's 14.7 "PSI" not the 0 "PSIG" that is trapped inside the fork tube.
       Would be 0 "PSI" if you pull out all the air.
   Next; Assuming the 29.7 PSI that both agreed to is a real number.
              Next; Multiply that 29.7 PSI X the Square area of the Upper fork tube. (!.75 square inches)
                 It works out to about 52 pounds of force..

* if you think about it, Steve's forks could not actually go solid as MOB suggested.
      {because there is a pocket of air on top of the oil}
    Unless you go to extreme pressures, that air is always there. (Compressed by the fork movement)
    NOTE: That air (because of the very small area) did go to a much higher pressure than 29.7 PSI.
                 The air was compressed and effected the movement of the fork tubes.
                     Which proves what S and T are saying. 

    Here is simple test you can do to show that air helps the spring.
       Draw the air out of the fork's and watch what happens. 
         Answer; The forks will move down.

* I did mention riding to the top of a mountain, or at sea level... what is the weight of an unladen sparrow?
       Err; A Sparrow's weight is effected by gravity, not air pressure.
             Air pressure decreases as you go up.

* Yes I can and do drink a little alcohol.
         But; I'm a real lightweight. I can't drink e'nuff to touch your share. {I would die}
         Note;  At the rally's I don't drink a lot of my "shine".
                     I give "it" to others,,,  so I can watch the fun

Ride safe, Ted

PS: DC, your forks are leaking while riding too. Most of the oil is blown away.
      NOTE: The trapped pressure when your on the bike {because of fork compression} is possibly pushing the seal tighter and slowing the leak. {MOB sez this pressure doesn't exist}   :rotflmao:
                When parked; there is less pressure to keep the seal tight and the leak may increase.
                   Plus; with no wind to blow the oil away, it accumulates and is easier to see.     
14 Connie (Traveler II)
03 Connie (Buddy)

To contribute to "OtP", (Chg. Card or paypal)  Click Here
(For Paypal) send to treasurer@cog-online.org

Online MAN OF BLUES

  • I Need a Life
  • ******
  • Posts: 6944
  • AREA: North Central Area
  • COG#: 5977
  • Membership Level: Active
Re: Fork leak when bike is sitting
« Reply #33 on: July 25, 2017, 04:06:12 am »
 :41: :41: :41: :41: :41: :s_laugh: :41: :41: :a012: :NIGHT_1:

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW

Offline Steve in Sunny Fla

  • Industry Member
  • I Need a Life
  • *
  • Posts: 7360
  • AREA: Southeast Area
  • COG#: 6977
  • Membership Level: Active
C-14 ECU flashing for performance and rideability enhancement
C-10 Carb work , cams, & performance enhancements
 " Modifications for sport-tourers, BY a sport-tourer"
https://sites.google.com/site/shoodabenengineering/home