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General Category => Modifications => Topic started by: jyrki on December 19, 2018, 12:03:44 PM



Title: To make front fork stiffer
Post by: jyrki on December 19, 2018, 12:03:44 PM
Hi, what would you recommendate to make front suspension stiffer? 1988 fj1200, original springs, 483mm. Stiffer springs from some dealer?


Title: Re: To make front fork stiffer
Post by: FJmonkey on December 19, 2018, 12:31:12 PM
Stiffer or perform better? Straight rate springs have been the budget choice for stiffer springs. Installing the RPM valves and straight rate springs are a major improvement. I have the valves and noticed a huge improvement when I installed them. The reflective dots glued to the freeway between lanes now feel like they are just paint and not a bump.


Title: Re: To make front fork stiffer
Post by: Pat Conlon on December 19, 2018, 12:43:38 PM
After experimenting with different oil levels in your forks, the next step is to consider the fork springs.
For a 550 lb street bike the oem Yamaha springs were light @ .644 kg/mm so I would start there.

1) Progressive springs are the easiest plug and play option: https://www.progressivesuspension.com/product/1465/fork-spring-kit (https://www.progressivesuspension.com/product/1465/fork-spring-kit)
They offer a mild upgrade over the stock springs.

(https://www.progressivesuspension.com/assets/images/products/fork-spring-kit_2.jpg.ashx?width=450)
 
 Any heavier springs will turn your front forks into pogo sticks. They will over whelm the oem damper rod valving and the spring rebound will become annoying. Plan on upgrading the fork valves to match the heavier spring rates.

2) RPM fork valves and .80 kg/mm matched straight rate springs give you a very nice ride.
http://www.rpmracingca.com/proddetail.asp?prod=M/C:RPMForkValve&cat=33 (http://www.rpmracingca.com/proddetail.asp?prod=M/C:RPMForkValve&cat=33)

(http://www.rpmracingca.com/prodimages/large/M C RPMForkValve-1.jpg)

Additional discussion: http://www.fjowners.com/index.php?topic=7486.0 (http://www.fjowners.com/index.php?topic=7486.0)

If money is a concern, try the straight rate .80 kg/mm springs now and save your money and add the RPM valves in the future.

3) Race tech makes valves for our FJ they call "cartridge emulators"  
They can handle much heavier fork springs than the RPM valves, up to 1.0 kg/mm
http://racetech.com/ProductSearch/12/Yamaha/FJ1200/1986-89 (http://racetech.com/ProductSearch/12/Yamaha/FJ1200/1986-89)

Over the years I've had all three of the above options ^^ on my FJs.... I like the RPM set up the best for street duty.

Hope this helps.

Pat
.




Title: Re: To make front fork stiffer
Post by: Motofun on December 19, 2018, 01:01:32 PM
Me personally? I'm not a fan of progressive springs.  They're a compromise.  If you have buy new springs buy the proper straight rate set up for your weight and riding style.  If you have no money, you can decrease the sag by the use of shims above the spring stack.  This is an old school technique and not the best solution but better than nothing.

I should add you lose travel with this technique so you will bottom out earlier....do not over do it.  quarter inch perhaps?

You know, after reading this a third time...If you have maxed the stock preload and it's still too "soft" I wouldn't go any further.  I was flashing back to my old CBX days.....


Title: Re: To make front fork stiffer
Post by: FJ_Hooligan on December 19, 2018, 02:11:02 PM
A cheap trick to stiffen up the stock spring is to cut the closely wound section of coils off (see Pat's picture of springs above).  Use a longer spacer to make up for the loss of length.  The resulting spring will have a higher rate without wasting fork travel to collapse the close coil section. 

Hoffman did this and it works well as a poor man's solution to initial fork performance improvement.  You would definitely want to move onto better (more expensive) solutions as money allows.


Title: Re: To make front fork stiffer
Post by: andyoutandabout on December 20, 2018, 07:54:48 PM
It’s Christmas, treat yourself to the RPM valves. They are kinda other worldly when set up with the right weight springs and fork oil volume/grade.


Title: Re: To make front fork stiffer
Post by: ZOA NOM on December 20, 2018, 07:57:04 PM
Don't forget the fork brace to keep the springs in line...

(http://rpmracingca.com/prodimages/large/M%20C%20ForkBrace-1.jpg)


Title: Re: To make front fork stiffer
Post by: andyoutandabout on December 20, 2018, 08:00:11 PM
Rick is right. The brace is another essential. The front end will thank you. These additions are money well spent. Don’t forget engine bars if you haven’t got a pair yet.


Title: Re: To make front fork stiffer
Post by: ZOA NOM on December 21, 2018, 06:06:08 AM
Rick is right. The brace is another essential. The front end will thank you. These additions are money well spent. Don’t forget engine bars if you haven’t got a pair yet.

It's a little early to question the guy's bravery Andy...  :rofl:


Title: Re: To make front fork stiffer
Post by: axiom-r on December 21, 2018, 04:57:45 PM
Or - just stiffer front forks.....

 :mocking:

(https://farm5.staticflickr.com/4337/36179390113_37e993cdae_z.jpg)


Title: Re: To make front fork stiffer
Post by: aviationfred on December 21, 2018, 06:54:35 PM
Or - just stiffer front forks.....

 :mocking:

(https://farm5.staticflickr.com/4337/36179390113_37e993cdae_z.jpg)

I waiting for someone to bring up USD 50mm forks  :biggrin:


Fred


Title: Re: To make front fork stiffer
Post by: Mike Ramos on December 22, 2018, 08:04:49 PM
Or - just stiffer front forks.....

 :mocking:

(https://farm5.staticflickr.com/4337/36179390113_37e993cdae_z.jpg)

I waiting for someone to bring up USD 50mm forks  :biggrin:


Fred

Gentlemen,

True works of art, no doubt about it! 

One can easily & with certainty understand the enjoyment and novelty of modifications.

Improved master brake cylinders, calipers & discs; modern suspension components such as a rear shock, fork springs & brace as well as Fork Valves (or emulators).

Individual air filters, timing advance, carburetor re-jetting and improved exhaust system to allow for a free breathing engine without a doubt add to an exceptionally improved riding experience.

No question it is a pleasure to individualize to one’s own personal preference and enhance the performance of a basically sound motorcycle platform. 
   
However, and with no intention of being trenchant, when does the FJ begin to lose its’ unique character?

It seems as if once a modification is accomplished that is not actually needed for “top shelf” STREET BASED performance, the uniqueness & appeal of the old FJ is perhaps compromised.

Just to make clear, the effort and the ability to install the USD's is admirable!   

Ride safe,

Midget







Title: Re: To make front fork stiffer
Post by: Tuned forks on December 22, 2018, 08:38:49 PM
Mike, I've wondered that too.  As wheels get replaced, suspensions get replaced, brakes get replaced, when is it no longer a FJ?  When the engine is replaced, the frame, the bodywork?  Not sure as I'm still new here.  I suppose it's still a FJ because in the hot rod world you can replace the entire drivetrain, brakes, suspension, change the bodywork, interior, etc and it's still called a '32 Ford or '69 Camaro or whatever.  I'd be curious to read others' comments on this subject.

Joe


Title: Re: To make front fork stiffer
Post by: Millietant on December 22, 2018, 08:40:01 PM
An interesting conundrum Midget, but in my mind you’re actually missing the point of the “uniqueness and appeal” of the FJ.

As a long term FJ owner, the appeal of the FJ is that at over 30 years old, with a small number of cost-effective modifications, it can perform in a way that can match what’s available on the market new today (within the confines of average owner/rider ability) and is a totally relevant vehicle (and mode of transport) on today’s roads.

I believe the uniqueness of the FJ is the way it handles its duties in such an unruffled and matter of fact way, across a whole spectrum of situations, primarily due to its simple but hugely effective engine and capable chassis.

All of the mods we do seem to be about enhancing its inherent strengths - rather than eliminating weaknesses - that’s the magic of the FJ today - a stock one is still an awesome road bike today, but a modified one can be Mega !!


Title: Re: To make front fork stiffer
Post by: Millietant on December 22, 2018, 08:56:00 PM
Joe. - I think the biggest difference between the hot rods and the FJ in the terms you refer to, is that the rods alter the intent and purpose of the base vehicle (ie they take a cheap family runabout and change its whole character), totally redesigning it to perform different duties to the original, whereas we generally try to just improve the way the FJ carries out it’s intended duties.

I know that there are some exceptions and I applaud these bikes, but the majority of us are still captivated by the original and are just trying to optimise them to perform to modern standards for those duties (without splashing out substantial cash on a new bike).

Although personally, I still get a buzz when a modern “superbike” owner/rider realises just how good a well
set up 30 year d FJ is on the road.


Title: Re: To make front fork stiffer
Post by: T Legg on December 22, 2018, 09:24:22 PM
    I still love to ride my 71 cb750.It is still a very capable bike and i love giving modern bikes a run for their money with a completely stock looking vintage bike but no matter what i do to it it wont be competitive with a modern bike.I take pride in how well an old bike rides.when I'm riding my fj 1100 it is more than competitive enough for me to keep up with modern bikes and with my full fairing and black paint scheme i take pride in the shock most riders show when i tell them the fj is 34 (almost thirty five ) years old.I was a member of the antique motorcycles club but the main emphasis was in having the bike as close as possible to the day it came off the assembly line and i find that to be incredibly boring. 


Title: Re: To make front fork stiffer
Post by: Mike Ramos on December 22, 2018, 11:34:31 PM
An interesting conundrum Midget, but in my mind you’re actually missing the point of the “uniqueness and appeal” of the FJ.

As a long term FJ owner, the appeal of the FJ is that at over 30 years old, with a small number of cost-effective modifications, it can perform in a way that can match what’s available on the market new today (within the confines of average owner/rider ability) and is a totally relevant vehicle (and mode of transport) on today’s roads.

I believe the uniqueness of the FJ is the way it handles its duties in such an unruffled and matter of fact way, across a whole spectrum of situations, primarily due to its simple but hugely effective engine and capable chassis.

All of the mods we do seem to be about enhancing its inherent strengths - rather than eliminating weaknesses - that’s the magic of the FJ today - a stock one is still an awesome road bike today, but a modified one can be Mega !!

Good evening,

Having experienced over 275,000 miles with the FJ, I concur completely with your comments.
 
My FJ has every modification possible: modern pre-balanced rims & tires, radial master brake cylinder matched to silver dots with the very best discs available; R.P.M exhaust system, suspension front & rear and fork brace.  Strengthened swing arm, engine tuned professionally (including timing & jetting). 

In addition, an XJR alternator is utilized & LED lighting front & rear is improved as to be on par with any other newer motorcycle.  Voltmeter, oil temperature & oil pressure gauges have been added.
   
As mentioned in my previous posts over the years, the FJ as configured with the aforementioned modifications all improve the inherent qualities of the FJ making it among the best all-around motorcycles available.  There is no doubt the character & “uniqueness and appeal” remain intact. 

My original thought (perhaps it should have been posed as a question) pertained solely to the installation of USD’s and if the FJ loses some of its' unique character. -  "It seems as if once a modification is accomplished that is not actually needed for “top shelf” STREET BASED performance, the uniqueness & appeal of the old FJ is perhaps compromised".

And yes, it is interesting to observe the reactions of other riders (and the occasional automobile) when it is discovered a 30 year old motorcycle is quite competitive!

Ride safe...!


 



Title: Re: To make front fork stiffer
Post by: ribbert on December 23, 2018, 07:19:44 AM

Mike, I've wondered that too.....when is it no longer a FJ? 

Joe

I reckon you can call it an FJ as long as it has the motor and frame.

Noel


Title: Re: To make front fork stiffer
Post by: ribbert on December 23, 2018, 07:24:58 AM

....in the hot rod world you can replace the entire drivetrain, brakes, suspension, change the bodywork, interior, etc and it's still called a '32 Ford....

Joe

Like the bloke that's had the same axe for 50 years and only replaced 3 heads and 5 handles in all that time.

Noel


Title: Re: To make front fork stiffer
Post by: chiz on December 23, 2018, 12:02:59 PM
Just my two pennies pretty sure I will never install any inverted forks... Don't like how they look especially on an older bike no mater how well well they improve handling.

 Lez


Title: Re: To make front fork stiffer
Post by: ZOA NOM on December 23, 2018, 12:07:54 PM

Mike, I've wondered that too.....when is it no longer a FJ? 

Joe

I reckon you can call it an FJ as long as it has the motor and frame.

Noel

Horse shit. If it doesn't have that fairing, those lines, that seating position, it's not an FJ.


Title: Re: To make front fork stiffer
Post by: Pat Conlon on December 23, 2018, 12:47:14 PM
OEM purists vs Modifiers, that debate is still alive and well. It's been around for a long time.
It can be divisive, we vs they, which seems common in today's world.

Out on a ride up to Palomar yesterday I stopped at the Hideaway Cafe (by Lake Henshaw) a local biker meeting point, and I overheard a comment from 3 guys in the parking area who were standing around looking at my '84, "Nice bike, but that's not an FJ anymore...."

...maybe so, but I noticed that nobody was standing around looking at their bikes.

Everyone knows that the USD fork swaps are reversible, right?
If you don't like them, go back to those spindley oem 41mm fork tubes. I know of NO ONE who has ever removed the USD's from their FJ to go back to oem. NO ONE.

Try them, you might like them, if not, at least you will know what the fuck you are talking about.

"There is a principle which is a bar against all information, which is proof against all arguments, and which cannot fail to keep a man in everlasting ignorance—that principle is: Contempt prior to investigation."

....besides, even Mike knows.... the USD's gets the chicks.


Title: Re: To make front fork stiffer
Post by: Grey runner on December 23, 2018, 01:46:22 PM
You don't have to go the USD route to upgrade, these are Thunderace forks if it wasn't for the different front fender you wouldn't spot the "mod"

(https://farm5.staticflickr.com/4917/44619237400_a973a348ed_k.jpg) (https://flic.kr/p/2aYRfLy) (https://flic.kr/p/2aYRfLy)


Title: Re: To make front fork stiffer
Post by: Millietant on December 23, 2018, 02:58:32 PM
Lovely looking bike Mr Runner  :good2: - agree on the Thunderace front end, still looks standard...ish.

Personally, I just prefer the look of my USD's, I think they really suit my 3CV, but your set up looks beautiful as well.

A modified FJ, but still very much, and clearly, a FJ in heart and soul.


Title: Re: To make front fork stiffer
Post by: Pat Conlon on December 23, 2018, 03:18:29 PM
Beautiful FJ Chris!  :good:

Yes indeed...for conventional forks, the 48mm stanchion tube T-Ace cartridge forks would be my first choice.

Never a need for a fork brace with those beefy tosdada fork tubes.


Title: Re: To make front fork stiffer
Post by: Bill_Rockoff on December 24, 2018, 05:38:56 AM
I overheard a comment from 3 guys in the parking area who were standing around looking at my '84, "Nice bike, but that's not an FJ anymore...."
FJs would have come from the factory just like yours, if they had discovered "Braking" and "Suspension" back in '84 the way they had already discovered "Power."

"Nice air conditioning indoor plumbing, but that's not a Victorian mansion anymore...." Well, it would be, if they had known then all the things we know now.


Title: Re: To make front fork stiffer
Post by: ribbert on December 24, 2018, 08:01:07 AM

Mike, I've wondered that too.....when is it no longer a FJ? 

Joe

I reckon you can call it an FJ as long as it has the motor and frame.

Noel

Horse shit.


Happy Christmas Rick.

Noel




Title: Re: To make front fork stiffer
Post by: ZOA NOM on December 24, 2018, 09:18:19 AM
Merry Christmas, Noel.