Front Fork Air Pressure

Yamaha Star V-Max VMAX Motorcycle Discussion Forum

Help Support VMAX Forum:

Lotsokids

Well-Known Member
Joined
Jul 17, 2009
Messages
565
Reaction score
9
Location
Memphis, TN
I've tried the search engine on this forum and cannot get good results for some reason.

The manual says the front fork air pressure should be 5.7 - 14.2 PSI. I read that someone else is running at 0 PSI.

Right now mine is 0 PSI.

Thoughts? Opinions?
 

Lotsokids

Well-Known Member
Joined
Jul 17, 2009
Messages
565
Reaction score
9
Location
Memphis, TN
It's tricky. My compressor's gauge starts at 10. I think I put about 12 PSI in there.

I'm chasing down a high-speed wobble problem and trying anything at this point. One person said they installed Progressive springs and the wobble completely went away. I'm looking at them now, but hesitant to spend $80 on them.
 

brad bruggeman

Well-Known Member
Joined
Apr 19, 2010
Messages
148
Reaction score
1
Location
tell city
It's tricky. My compressor's gauge starts at 10. I think I put about 12 PSI in there.

I'm chasing down a high-speed wobble problem and trying anything at this point. One person said they installed Progressive springs and the wobble completely went away. I'm looking at them now, but hesitant to spend $80 on them.
I agree with you.I wouldn't want to spend the money if you don't know if it would work.But it did work on my 95.I had a high speed wobble that wouldn't go away.The only way it would stop is once it was doing it,you just simply had to back off of the throttle. That is pretty embarrassing if you were playing with another bike.The Yamaha mechanic told me that I wouldn't like it because it would ride too rough.But the deciding factor for me was that I had this same experience with a 88 Yamaha venture that I had ouned previously that did the same thing.I replaced the front springs with progressive springs and it worked like a charm.It handled so much better.I then realized that I made the right decision.It did the trick on my vmax also.Completely solved the problem.I have had it up to 135-140 a few times since i have had the progresive springs wih no problems,much better.I believe it was a good investment.What good is a vmax if you can not go fast safely.Hope this helps you,let me know what you decide and if it works..
 

Lotsokids

Well-Known Member
Joined
Jul 17, 2009
Messages
565
Reaction score
9
Location
Memphis, TN
Thanks Brad. I think that will convince me to get the Progressive springs.

I have a business trip to the U.S. soon, so I can bring them back no problem. Otherwise I need to pay a billion dollars for shipping, then pay 27% VAT tax when they arrive. My options are few.
 

Traumahawk

Well-Known Member
Supporting Member
Joined
Dec 12, 2011
Messages
8,141
Reaction score
372
Location
Lawton, OK
I just read where your running 0 psi. No wonder it feels spooky. When I first bought my 07 Vmax....I rode it hope from the dealership (used....I bought it 3 years ago). It felt really loose....kinda spooky.

After I got home.....and read the manual.....and it told me the pressures. I put mine at 10 psi......MAJOR improvemt. Did anyone show you the proper tool to put air in the forks? Because with a normal air compresser, when you move it away, there will be some air that escapes. It makes it very hard to get the same amount in both.

You need something like this
http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=0F74DM8P3Y776TBN9V3T

OH.....you ONLY run 0 psi in forks with aftermarket springs......running 0psi in stock forks can damage them.
 

Lotsokids

Well-Known Member
Joined
Jul 17, 2009
Messages
565
Reaction score
9
Location
Memphis, TN
...with a normal air compresser, when you move it away, there will be some air that escapes. It makes it very hard to get the same amount in both.
Interesting. When it stops raining next week I'll try it out. :damn angry:
I bumped it to about 16 PSI, then used a stick style gauge to let air out to an even 12 PSI in both. I'm confident they are close.
 

DMAN999

Well-Known Member
Joined
Apr 15, 2010
Messages
3,308
Reaction score
6
Location
Hamburg, NY
I used to use a bicycle air epump that had a gauge on it to add air when I had the stock springs. I kept them at around 10 psi.
Now with the Progressive Springs I don't use any air and my front end still feels 1000x better than it did with the stock springs.
I have never had an issue at high speed either way though.
I have regularly hit 140-145 mph with both the stock fork springs and with the Progressives.

I installed the stock length Progressive fork springs (11-1144 -1993 - 2007) with 10 wt. Maxima Racing Fork Fluid and the difference from stock is amazing.
I weigh around 180 lbs., most guys over 200 lbs. tend to like 15 wt. fluid better.
My bike is much smoother at highway speeds (I can actually see what's in my mirrors at 60-80 mph now) and they tighten up quickly in the curves.
Also brake dive is virtually eliminated.

I attached a picture of the Progressive and Stock Springs so you can see the difference.
 

Attachments

Specs95t

Well-Known Member
Joined
Aug 2, 2015
Messages
341
Reaction score
1
Location
Albany NY
I have had similar experience recently.

I bought mine in August - rode it home 120 miles with 0 psi, stock springs - scary on turns....

bumped up to 12 psi - much better...

swapped out stock springs with progressives (0 psi) - way better - a little bouncy @ 35 mph on a hot summer day...

replaced existing fluid with Amsoil synthetic ATF - reduced bounce @ 35 mph 80% gone, still some bounce on a hot summer day...

then it dawned on me! waited for next hot summer day, rode a few miles, till I felt some bounce @ 35 mph - stopped and let out the built up pressure - THATS IT

nice ride, no dive, good absorption on bumps, no bounce issue, good 2up handling - haven't looked back...
 

pcarroll

New Member
Joined
Feb 22, 2021
Messages
2
Reaction score
0
It's tricky. My compressor's gauge starts at 10. I think I put about 12 PSI in there.

I'm chasing down a high-speed wobble problem and trying anything at this point. One person said they installed Progressive springs and the wobble completely went away. I'm looking at them now, but hesitant to spend $80 on them.
Check your steering head bearings. I had the same problem and once mine were adjusted correctly the problem completely dissapeared.
 

bigpapacronk

New Member
Joined
Apr 29, 2020
Messages
2
Reaction score
0
Personal preference. With stock springs 7-10lbs is a good average.

Most guys with aftermarket springs run without air
I just had my fork seals replaced, was advised by mechanic to run at 0 psi, as to not risk blowing out seals again. If I wanted more stiffness, get spring add on's.
 

Fire-medic

Well-Known Member
Supporting Member
Joined
Mar 25, 2011
Messages
11,245
Reaction score
1,284
Location
Miami Florida
I just had my fork seals replaced, was advised by mechanic to run at 0 psi, as to not risk blowing out seals again. If I wanted more stiffness, get spring add on's.
I am not a professional mechanic.

Uh, no! That's total b.s. what he told you.

Sorry, but he is wrong. You entrusted him with your bike, but you can safely-ignore that advice. If you weigh >135 lbs you should be running air in the forks, unless you have Progressive Springs, which you said nothing about. The P.S. kit recommends no air pressure. If you have OEM springs and are average weight, or heavier, you need air in the forks. Actually, whatever your weight, I'd run air. The psi would just be for less-weight, less psi. More weight, more psi.

Assuming you are average weight or >, if you have to nail the brakes to avoid some texting, idiot driver, and you have no air pressure, you will easily bottom-out the forks, possibly resulting in a loss of control. Bottomed-out forks and trying to execute a rapid directional change to avoid an accident is a recipe for vehicle dynamics disaster. Add-in broken pavement, engine oil, diesel fuel, anti-freeze, ATF, or whatever other traction-reducers you can encounter, you need all the help you can get.
 
Last edited:

one2dmax

Well-Known Member
Joined
Apr 6, 2006
Messages
15,829
Reaction score
581
Location
Derby Kansas
I do NOT run air provided you resolve the weak factory spring rate. All that does is airiate the oil and put bubbles into it even more then no air. Plus it's a crutch for inadequate fork spring rates. IF you are running stock springs then you have no choice. Otherwise get progressive or racetech and run NO air pressure.
 

Jgas

Active Member
Joined
Jun 1, 2021
Messages
35
Reaction score
17
Hey. New guy here. Been racing off road for over 40 yrs. Exactly same psi. Wont matter as long as its close. Springs oil level and oil weight should all go together. Might as well while you are in there. Mismatched front to rear tire size often cause headshake. Even uneven tire psi. Whoever mentioned steering head bearings was a genius. Very common. Usually either too loose or out of grease. Or out of grease and worn. My 98 max shook only under decel and very briefly from 95 to 90 ish. It was all 3. Loose head bearings low fork oil and no air. All 4 actually. High rear tire psi and low front tire. Uh... i think that is 5?
 

bigpapacronk

New Member
Joined
Apr 29, 2020
Messages
2
Reaction score
0
I am not a professional mechanic.

Uh, no! That's total b.s. what he told you.

Sorry, but he is wrong. You entrusted him with your bike, but you can safely-ignore that advice. If you weigh >135 lbs you should be running air in the forks, unless you have Progressive Springs, which you said nothing about. The P.S. kit recommends no air pressure. If you have OEM springs and are average weight, or heavier, you need air in the forks. Actually, whatever your weight, I'd run air. The psi would just be for less-weight, less psi. More weight, more psi.

Assuming you are average weight or >, if you have to nail the brakes to avoid some texting, idiot driver, and you have no air pressure, you will easily bottom-out the forks, possibly resulting in a loss of control. Bottomed-out forks and trying to execute a rapid directional change to avoid an accident is a recipe for vehicle dynamics disaster. Add-in broken pavement, engine oil, diesel fuel, anti-freeze, ATF, or whatever other traction-reducers you can encounter, you need all the help you can get.
Thanks for your advice, I'll be getting PS very soon.
 

Latest posts

Top