Seen an air fork adapter for 1993+?

[Fire-medic]

I got this today and hadn't seen it before, it even stumped The Captain, with whom I spoke today. He hadn't seen one, either.

I happen to like the air fork function on my 1992 40 mm downtube front end, it's so-nineteen-eighty's! I like being able to fine-tune the front end w/a bit of air pressure.

When I switched the entire front end over to a 43 mm 1993+ front end, I was sad to lose the air adjustability.

Today I got this front end mod w/a parts bike I will be posting-up and wondered, "how-many of our intrepid readers have knowledge of this setup?" I recall in the 1970's when long-travel motocross suspension came into use, kits were available like this for nearly any competitive dirtbike, but I don't really-recall seeing them for streetbikes.

The fork cap is tapped for a fitting which allows a balance tube to interconnect left and right downtubes, and one has a Schrader valve. The balance tube is a plastic one, similar to the air shock hose plastic material that comes stock on Gabriel Hijackers and similar. Since the air pressure is <20 psi, in our forks, it should work just-fine.

Here are the pics. I'm sure if I went into the backs of the 1970's/'80's bike mags, I would see some of these advertised in those 1-&-2 column inch ads next-to the facial hair glue-ons that were popular items in the magazines of the day: "Fu-Manchu in five minutes! Or, choose from a Van Dyke!"

 

[gamorg02]

93 and up forks have the Schrader valves just no crossover, wonder why the tapped the caps.

-garrett now Free

 

[m-cman]

I had one or two of those sets on street bikes in the 70's. Had forgotten about them... Can't remember which bikes. Changed bikes every year from the 60's thru the 80's.

 

[Miles Long]

lhttp://www.kawasakimotorcycle.org/f...essive-suspension-air-fork-balance-kit-2.html

Progressive Suspension makes a balance kit, or used to make one.... Dennis Kirk now lists it as "no longer available"
I fabricated a balance setup years ago, using 1/8" NPT x 1/4" compression fittings, copper tubing, a pressure gauge, and a air valve. Even with aftermarket Progressive springs, it's still nice to be able to adjust fork pressure.
For long trips on smooth highways, I keep about 8 psi in the forks.
Cheers!

 

[one2dmax]

Definitely a rare part and looks homemade for sure.

 

[Fire-medic]

93 and up forks have the Schrader valves just no crossover, wonder why the tapped the caps.

-garrett now Free

Thanks, Garrett, yes they do, I guess I haven't been looking that closely at the front of the bike, concentrating more-on the upcoming roadway as they teach you to scan in the mcy safety classes. That's my excuse tonight...

About the only thing I can think of is balancing both downtubes at the same time, avoiding any side-to-side discrepancy.

 

[pjmac5]

Thanks, Garrett, yes they do, I guess I haven't been looking that closely at the front of the bike, concentrating more-on the upcoming roadway as they teach you to scan in the mcy safety classes. That's my excuse tonight...

About the only thing I can think of is balancing both downtubes at the same time, avoiding any side-to-side discrepancy.

Progressive sales an adapter kit for the 416 Rear Air Shocks that allows you to adjust the Air pressure in both shocks at the same time. That way you can change pressure quickly depending on load, weather, etc.

http://shopping.yahoo.com/components/large_image;_ylt=AvQCxAmY20zqT354ueCjtuJj0cUu?id=766333583

It looks like a similar type of set up. I believe these kits are still available as the 416 is still being sold.

 

[DMAN999]

Honestly I can't see any real need for that Balancer tube on a Vmax.
A hand pump is supposed to be used to fill them and as long as you have a good air gauge they will be pretty darn even anyways.

 

[Fire-medic]

Honestly I can't see any real need for that Balancer tube on a Vmax.
A hand pump is supposed to be used to fill them and as long as you have a good air gauge they will be pretty darn even anyways.

"I have something technical and you don't!":biglaugh:

Probably serves more of a useful purpose than paying $ to get 21% more nitrogen gas in your 'tyres' (I'm feeling British today), since the atmosphere is 79% nitrogen to begin-with. :rofl_200:

I think you could remove the valve stems & add another Schrader valve between them after running a balance tube from a couple of compression fittings on the downtube caps.

 

[cyclejohn]

I have the Progressive air balance kit on my '03 Max. Mine has a clear crossover tube. I installed it on the bike not long after I bought it in '03.

 

[SFCMcGan]

Unless you have a manual preload adjuster, having a cross over on air assisted suspensions has its merits... say you have a very slow leak in the shcrader valve...on one side... at some point 1 fork will have pressure and the other won't... this could cause a huge hard braking issue.. it could cause the bike to "Plow" in the corners etc.. A cross over would accomplish 2 things...air pressure would be constant between the 2.... and if 1 was completely out of air... so would the other... wait... I guess in reality... it is the same....

 

[DMAN999]

SFCMcGan,
while I see your point, I had Stock Fork Springs in my Max for about 10 years.
I used to check the fork air pressure 1-2 times a year and they were always almost exactly the same.
But when my left fork seal started to leak, it did lose a little air also (it was about 1.5-2 lbs down from the right fork).
I honestly couldn't tell a difference at all while riding.

I installed Progressive Fork Springs when I replaced the Fork Seals and now I don't use air in either fork.

 

[Fire-medic]

Well, the Ducati guys don't get a faster bike because they have carbon fiber fenders and OHC belt drive covers, but they look cool, it's something the next guy may-not have, and it makes your bike different from the next guy who has your make and model. It does have some functional benefit, even-if the average 'joe' isn't going to lap the Nurburgring faster than a $875,000 Porsche hybrid supercar because of it. It's more-practical than those 'road fairy' bells and the neckerchief tied-to the handlebar that the Harley guys sport-about with.

 

[SFCMcGan]

hmmm

 

[SFCMcGan]

SFCMcGan,
while I see your point, I had Stock Fork Springs in my Max for about 10 years.
I used to check the fork air pressure 1-2 times a year and they were always almost exactly the same.
But when my left fork seal started to leak, it did lose a little air also (it was about 1.5-2 lbs down from the right fork).
I honestly couldn't tell a difference at all while riding.

I installed Progressive Fork Springs when I replaced the Fork Seals and now I don't use air in either fork.

I hear you... may or may not make a difference the cruiser style... My ZX636 had no air pressure in 1 fork and it caused a noticeable mushy feeling going into a hard corner.... Once the pressure was corrected... the symptom went away... I am going to opt for Morely's manual adjusters...

 

[Miles Long]

Another advantage of having a manifold (crossover) arrangement is ease and accuracy of adding air - especially if you don't have one of the low-volume
micro pumps meant for filling air shocks.
Since you are adding twice as much air than would be required for one fork, it's much easier to fill to the desired pressure, without going over and having to bleed off. I use a regular bicycle pump, it's works dandy.
I don't understand why Yamaha eliminated the manifold, after the fork upgrade. A step backwards, for sure. Cost-saving, no doubt?
Cheers!

 

[DMAN999]

I hear you... may or may not make a difference the cruiser style... My ZX636 had no air pressure in 1 fork and it caused a noticeable mushy feeling going into a hard corner.... Once the pressure was corrected... the symptom went away... I am going to opt for Morely's manual adjusters...

If you still have the Stock Fork springs, you should definitely install some Progressive (~ $75-$80) or Racetech Springs (~ $100) when you do those Preload Adjusters.
The aftermarket springs make a Huge difference and are well worth the price.

 

[Traumahawk]

If you still have the Stock Fork springs, you should definitely install some Progressive (~ $75-$80) or Racetech Springs (~ $100) when you do those Preload Adjusters.
The aftermarket springs make a Huge difference and are well worth the price.

I have the progressives and the preload adjusters...BIG improvement over stock.

 

[SFCMcGan]

If you still have the Stock Fork springs, you should definitely install some Progressive (~ $75-$80) or Racetech Springs (~ $100) when you do those Preload Adjusters.
The aftermarket springs make a Huge difference and are well worth the price.

That is definitely the plan!

 

[johnpclynch]

Easy to make a balancing line yourself - 2 schrader adapters (90 degree?) some hose and an inline schrader valve to set the pressure
The difficulty is making it so that it is reliable and won't pop a hose off