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Technical Help Forum
Started by photocodo at 07-12-2010 11:30 AM. Topic has 17 replies.
  
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 07-12-2010, 11:30 AM
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photocodo
 
Joined on 06-29-2010
Orlando, FL
Posts 23
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I recently got my cx500 which is also my first bike. The front forks are very soft and it seems like they sag a little when I get on the bike or hit a bump. Does this sound like something that is an easy fix? A friend said that it may just need more fluid or they may need to be rebuild. If they do need to be rebuild, is that something that I can do on my own or should I have someone else do it? is it expensive? Thanks for the advice.
photocodo
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.
1978 cx500 in transition to be a 1978 cx500 cafe racer
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07-12-2010, 12:27 PM
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Timothy_D
Joined on 04-22-2006
Santa Rosa, CA
Posts 1,585
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Re: front suspension is soft
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Honda CX500 front shocks are very undersprung.
This was solved a little in the later models with air adjustable shock systems, but even that only masked the problem.
Best bet is to upgrade to a better spring, and upgrade to either 15 or 20 weight fork oil.
CX500 Turbo, GL650I, Two CX650E's, and one Crown Jewel of the CX line- CX650T.
Why do I own five CX/GL bikes? Ask an alcoholic why he drinks.
Donating Member.
Sold: 1981 CX500D, 2- 1982 CX500T's, 1983 CX650C.
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07-12-2010, 1:17 PM
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rickbert
Joined on 01-05-2009
Missouri....60 mis East of KC
Posts 1,384
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Re: front suspension is soft
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What Timothy said and to answer your other question Yes alot of people here have done it themselves...you'd need a manual though.
1982 CX500C...22K miles...owned since 10/08
My age: 45
Bike's name: "Long Cool Woman in a Black Dress"
If you need to contact me personally send an email, I never get my pm's for some reason.
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07-12-2010, 3:09 PM
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photocodo
Joined on 06-29-2010
Orlando, FL
Posts 23
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Re: front suspension is soft
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Thanks guys, would it be better to just upgrade the front forks all together? if so what should I look for? has anyone done it?
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.
1978 cx500 in transition to be a 1978 cx500 cafe racer
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07-12-2010, 3:57 PM
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Timothy_D
Joined on 04-22-2006
Santa Rosa, CA
Posts 1,585
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Re: front suspension is soft
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With no adjustments, you can upgrade to the 80 or 81 CX500D air suspension forks.
'81 are the best.
With fairly major modifications, you can use any of the CB750, or CB900 forks.
Modifications required:
Triple Tree, full brake system compatible with the donor bike's forks, wheels with dual discs, mount for the instrument cluster, spacers for the steering head bearings. Steering head bearings that are compatible with the inner diameter of the new fork legs, but fit inside of the CX500 races.
So, worth it, or pain in the ass, you have to decide.
CX500 Turbo, GL650I, Two CX650E's, and one Crown Jewel of the CX line- CX650T.
Why do I own five CX/GL bikes? Ask an alcoholic why he drinks.
Donating Member.
Sold: 1981 CX500D, 2- 1982 CX500T's, 1983 CX650C.
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07-13-2010, 6:20 PM
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SamsGL650I
Joined on 05-30-2010
Annville, PA
Posts 93
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Re: front suspension is soft
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Hi photocodo, the guys have some good ideas above.
I did this with my 650., and it made a great difference- new progressive springs and 20 weight fork oil. These upgrades are relatively inexpensive ( about @$80 for a set of new springs).
Your probably running your original springs (now @25 years old), and if you dont know when your fork oil was last changed, then it is overdue!
These projects are well within the DIY'ers realm.
Post us if you proceed,- super knowledgeable good members abound here.
1983 Honda GL650I
Kawasaki EN500LTD
1st Bike: @1974 Honda CL 175
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07-13-2010, 10:20 PM
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photocodo
Joined on 06-29-2010
Orlando, FL
Posts 23
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Re: front suspension is soft
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Thanks Samsgl650I
I really like to do things myself, I just learn better that way and I am pretty mechanically inclined, however I have little motorcycle experience. If you know of any posts that go through that process that would be great, or a website explaining how to go about changing the springs. I have realized more and more how much information is on this forum, and knowledge. Thanks and where would you suggest getting the springs? Is there a specific size that I need? thanks again
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.
1978 cx500 in transition to be a 1978 cx500 cafe racer
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07-14-2010, 1:36 AM
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spanish bandit
Joined on 02-12-2009
southern spain
Posts 5,010
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Re: front suspension is soft
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 photocodo wrote: | Thanks Samsgl650I
I really like to do things myself, I just learn better that way and I am pretty mechanically inclined, however I have little motorcycle experience. If you know of any posts that go through that process that would be great, or a website explaining how to go about changing the springs. I have realized more and more how much information is on this forum, and knowledge. Thanks and where would you suggest getting the springs? Is there a specific size that I need? thanks again
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bit of help here 
when i feel the need,i do it,llego,ve 60,s
-----------------------------
2008.1982 honda gli silverwing [uk model ]
2010.1981 honda gli silverwing [uk model ]
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07-20-2010, 1:27 PM
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NashvilleCX500
Joined on 07-20-2010
Hendersonville, near Nashville, TN
Posts 3
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Re: front suspension is soft
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I recently purchased a 1979 CX 500 Custom for my son. The front end was extremely soft, my 220 lbs nearly flattened the front forks without the effects of braking. Having ridden a 1972 Suzuki Prospector when I was a kid, I recalled sacrificing 2 inner tubes for the stems and mounting them in the fork caps.
Not swimming in inner tubes any longer, this time I went to the tire store and scrounged two rubber valve stems. I stripped the rubber off and produced two 1-1/2 long brass stems. I then drilled holes in the fork caps and used JB Weld to secure the stems. Air up with about 20 PSI and the front end is much improved. Those of you in colder climates may be aware that Fox makes air only front shocks for snowmobiles.
Here is a photo, I'll let you know how it holds up with the 20 psi.
http://picasaweb.google.com/lh/photo/5oS3edbcyiQKRFMYuNPKsQ?feat=directlink
Steve Lissner
Nashville, Tn
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07-20-2010, 3:43 PM
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Abes_CW
Joined on 04-17-2007
saskatoon
Posts 3,036
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Re: front suspension is soft
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Welcome Nashville.
20 psi might be a bit high, my Interstate, designed with air shocks, says max 16. I'd hate for you to blow out a seal.
1983 GL650i
Had 4 CX/GL's at one point this year, down to one, next spring is another adventure!
age 38 (29 plus tax)
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07-20-2010, 4:56 PM
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SamsGL650I
Joined on 05-30-2010
Annville, PA
Posts 93
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Re: front suspension is soft
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Progressive Springs are available at www.bikebandit.com
They will have a listing of sizes to fit your bike.
Easy to install. Just peruse the online service manual, available in quick reference info for new members.
Most members here are now using fork oil (20) vs the old, original OEM rec of ATF.
1983 Honda GL650I
Kawasaki EN500LTD
1st Bike: @1974 Honda CL 175
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Yesterday, 5:11 PM
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RxRC
Joined on 06-14-2010
NW Minnesota
Posts 17
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Re: front suspension is soft
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It's shockingly soft. I'll bet it's sprung for someone near 100lbs.
Air is a really poor suspension medium and oil is only effecting damping. And no amount of pvc will help either. Making a longer preload spacer out of pvc will only add preload, it will not effect the spring's rate. To make the front end "stiffer, you'll need a stiffer spring.
Only because I'm in a hurry with this bike did I order Progressive springs. Not really what I want but I'm sure it will be an improvement. I always buy Race-Tech, straight rate springs for my bikes but of course they don't have any listed for the CX. I'm sure I could remove the stock springs and take all measurements and the could cross reference or make something for me but I figure that will just take too much time for me.
If you want to get the correct rate spring for your CX you can measure the overall length, i.d., o.d., and contact Race-Tech. Another source for springs is Rich Desmond at Sonic Springs. I have not contacted him.
Here are two charts for selecting fork spring rates.
http://www.mad-ducati.com/Technical/racetech/SpringChart.aspx
http://www.sonicsprings.com/catalog/calculate_spring_rate.php#calculate
"Giving the Ralph to the prairie scrub of Grand Forks is like dressing up drunken monkeys in snowmobile jackets and packing them into the Ordway....."
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Yesterday, 10:58 PM
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Abes_CW
Joined on 04-17-2007
saskatoon
Posts 3,036
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Re: front suspension is soft
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My forks were saggy, for sure, I've mentioned this in the general discussion forum. Leaky seals and low on fluid, but I discovered that a PO at some time had put the springs in backwards and upside down. Who knows what you have, and what weight oil you have. Soft springs ripple effect down the line to handling and braking, so it's a good idea to check them out. The factory springs are progressive, when put in correct. Long spring should be first with wide coils at the bottom, the spacer and then the short top spring. My 650 full kit had the short (loose coil) spring at the bottom, the long spring with the tight coils down. No wonder it felt like the frame was made of spaghetti when cornering with mild road undulations.
1983 GL650i
Had 4 CX/GL's at one point this year, down to one, next spring is another adventure!
age 38 (29 plus tax)
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Today, 7:25 AM
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FRANKO
Joined on 07-14-2010
Knoxville, Tennessee
Posts 10
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Re: front suspension is soft
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I'VE GOT SOME SAGGY STUFF GOIN' ON IT'S JUST
NOT ON THE BIKE!!
GL500I '82
RETIRED AND BORED!!
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Today, 9:01 AM
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RxRC
Joined on 06-14-2010
NW Minnesota
Posts 17
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Re: front suspension is soft
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| Abes_CW wrote: | | The factory springs are progressive, when put in correct. Long spring should be first with wide coils at the bottom, the spacer and then the short top spring. My 650 full kit had the short (loose coil) spring at the bottom, the long spring with the tight coils down. No wonder it felt like the frame was made of spaghetti when cornering with mild road undulations. |
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I'm pretty sure the springs are progressive no matter how they are installed. Can you explain how the spring would act differently depending on installation? I don't believe gravity would effect the springs action or rate.
Mike
"Giving the Ralph to the prairie scrub of Grand Forks is like dressing up drunken monkeys in snowmobile jackets and packing them into the Ordway....."
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Today, 9:27 AM
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Abes_CW
Joined on 04-17-2007
saskatoon
Posts 3,036
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Re: front suspension is soft
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The top spring is almost entirely preload. Sit on your bike, and the weight on the bike compress the forks almost the length of this spring. This is a downward force and one you want controlled at the top of the fork, not the bottom. Suspension undulation is an upward force, and the energy moves upwards so you want the energy to be captured as it travels up the fork. Wide coils first then stiffening up with more fork travel.
It's not simply gravity, you want to absorb the energy in the direction it travels. The force doesn't hit the entire system at the same time.
In my case, the preload spring was at the bottom of the fork, then the tight coils, then the loose coils at the top. Preload \/ force was being soaked up at the opposite end of the fork from the direction of energy, ^ energy was hitting the very soft remaining preload spring first, then the really tight stiff coils, then the medium soft wide coils of the long spring. The result being an unsettling pogo stick action in corners.
Hopefully that makes sense.
Progressive Springs are a big deal because Harley guys do it to upgrade. HD's stock have straight springs, and only one. Our bikes come from the factory with a variable rate spring, and a separate preload spring. Measure the length of the spring as per the manual to check against sag.
1983 GL650i
Had 4 CX/GL's at one point this year, down to one, next spring is another adventure!
age 38 (29 plus tax)
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Today, 10:48 AM
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RxRC
Joined on 06-14-2010
NW Minnesota
Posts 17
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Re: front suspension is soft
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It is not a downward force in this instance. The wheel is traveling upwards and your excessive wheel movement, pogo stick as you call it, is due to a lack of damping.
Anyway, I don't really want to argue about that, as my point was to say if riders want a more stiffly suspended motorcycle they need stiffer springs to get the correct suspension sag.
As far as Progressive Springs go, it won't matter which way they are installed except for one minor point. The tighter wound end will displace more oil.
"Giving the Ralph to the prairie scrub of Grand Forks is like dressing up drunken monkeys in snowmobile jackets and packing them into the Ordway....."
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Today, 12:14 PM
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Abes_CW
Joined on 04-17-2007
saskatoon
Posts 3,036
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Re: front suspension is soft
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True about the oil displacement, false about the spring orientation.
To say it doesn't matter in energy dissipation is baffling. Look at it from a perspective of a modern car. You are saying it wouldn't matter to have the real stiff part at the front of the car, and the soft stuff in the passenger compartment.
Imagine a simple experiment. An egg, a seat cushion, and some rigid styrofoam. The seat cushion and styrofoam together will have the same compression, spring rate regardless of how they are stacked. but put the soft foam first, and drop the egg from 2 feet. Reverse them, drop the egg and see if there is any difference.
It's pretty basic physics, adding time into the equation. you wan't to dissipate as much energy as possible before it reaches the end of the line, and in the case of hitting a bump, the upward force's end of the line is the top of the fork, the handle bars, and you.. A moderate bump will transfer the energy from the bottom up and the tight coils at the bottom will not compress, and the energy has traveled half way up the fork before it begins to be dissipated by the softer coils. Cut the amount of time in 1/2, and it will effect your handling.
There is a reason Mr Honda designed the forks the way he did, and why virtually all progressive springs have the tight coils at the top. It's not an accident.
As you said in another thread, one shouldn't take shortcuts with suspension, tires and brakes. To suggest to noobs that it doesn't matter is irresponsible.
1983 GL650i
Had 4 CX/GL's at one point this year, down to one, next spring is another adventure!
age 38 (29 plus tax)
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Honda CX500 & G... » CX500 GL500 Tra... » Technical Help ... » front suspension is soft
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