Why don't air bottles work on MX bikes?

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Spokes574

Member

Apr 27, 2001

171

0

• Jan 18, 2009

• #1

I got a set of air bottles to try to elliminate the harsh front end of my Y09 CR450R on the small braking bumps. The bottles only helped very little at full open. The bottles should easily simulate 10-20cc of lower oil height but it does not feel that way with the bottle setting to fully open. Why not?

I hear from folks it works well for trail riding but I can not see how if it doesn't work for MX, atleast on my bike.
The bottles do not even make the bike ride low in the stroke and it should. What gives?

Spokes574

 

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dirt bike dave

Sponsoring Member

May 3, 2000

5,348

3

• Jan 18, 2009

• #2

Never used bottles like you speak of, but lowering the oil height would mainly effect the last part of the travel, and would make the fork feel softer only when you were close to bottoming it out.

Sounds like you need less compression damping, or maybe the forks are still breaking in?

 

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Matt90GT

Member

May 3, 2002

1,517

1

• Jan 18, 2009

• #3

The bottles are not going to change the valving and spring rates in the forks. That is why they dont fix your issue.

Work on the valving and ICS spring rates on the forks.

 

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Spokes574

Member

Apr 27, 2001

171

0

• Jan 20, 2009

• Thread starter
• #4

I dropped the bike off at MDK for Front and Rear revalving.
They said that the SubTanks worked well with the older style single chamber Kayaba's but not on dual chamber forks. I have a 30 day money back guarantee, so I will be sending them back for a refund. i will use the cash to do the motor once cams are available at the end of February.

Spokes574

 

RM_guy

Moderator

Damn Yankees

LIFETIME SPONSOR

Nov 21, 2000

7,046

208

North East USA

• Jan 20, 2009

• #5

I have the Enzo sub tanks and they are amazing. The small chop disappears, even with adding additional oil. My forks have been re-valved and I thought they were great until I installed the tanks.

I was told that tanks that just hook into the air bleed screw hole have too much restriction at the hole and they don't perform right. The Enzo tanks require drilling out the hole to a larger size so the tank's own valving works like it's suppose to.

 

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Spokes574

Member

Apr 27, 2001

171

0

• Jan 21, 2009

• Thread starter
• #6

RM_guy
You are correct. The connection to the small bleed hole does not allow the subtanks to work effectively unless its drilled out and and create a larger orafice.
On the new dual chamber forks, subtanks are less effective than the older style single chamber KYB. The Subtanks are less effective if use the screw into bleed hole versions, especially on the new dual chamber forks. I felt maybe ~10% improvement with them fully open. That is not worth what I paid for them at all.

I was told that valving is a better way to go on the newer dual chamber forks than using the subtanks and much cheaper.

Also, the claim of no maintenance is not true. I removed the tanks after 1 ride and drained out ~2cc of oil from each tank.

Well, I guess we all have to learn the hard way once in the while.

Spokes574
California

 

whenfoxforks-ruled

Old MX Racer

~SPONSOR~

Oct 19, 2006

8,129

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Merrillville,Indiana

• Jan 21, 2009

• #7

I would think this set up would work better for trail bikes than mx. It is effectively giving your forks more volume? Look at the trials bikes with their valving in one side only? Setting them up with the larger holes instead of the air bleeders says alot about what it is doing. Stock mx bike, sag set properly, and you need stiffer or softer springs, you really need to get the valving to match. Using it for some other application, talk to MX Tech about the valving. The new 450, some like it, some hate it. Tells me that it is all in the set up. Be it oil, springs, clickers or valving. Bolt on magic, not likely? Trade a guy with an 08 and get some showas!

 

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Spokes574

Member

Apr 27, 2001

171

0

• Jan 24, 2009

• Thread starter
• #8

Old MX Racer, I gave up on the sub Tanks. I found out for the Y08+Y09 they made the tanks smaller due to clearing the dampner which could be affecting the overall perfomance of the tanks in addition to the small orvace used via the air bleed hole.

I gave up on the CRF450R Y09 suspension and dropped the entire bike off to MDK to get the front and rear redone. I have the new linkage, GPR stearing dampener, and 0.48 springs, but the bike still dances a lot on entrance to corners with braking bumps. Ya I tried lowering oil hieght in the front and that helped, but not to my standard. The bike is getting the suspension and engine done. I will have 55.5hp when I pick it up next week - Just like my Y0CRF450 Y05 MDK engine had.

I am tired of complaining about this bike, and just going to pay and get it fixed once and for all and get back to racing hard.

SPOKES574
California

 

Patman

Pantless Wonder

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Dec 26, 1999

19,765

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• Jan 24, 2009

• #9

Geesh and here I thought that the Y09CRF450 was supposed to be all that and more right out of the box. I wonder if all the stuff you are tacking on is really necessary and perhaps causing a lot of the issues you have mentioned previously? :think: A good suspension tune (MXTech is the only place I'll ever use) would seem like the best starting point for any bike, then work out what it may be lacking once you know how it really handles and puts down power. That's just me though.

 

whenfoxforks-ruled

Old MX Racer

~SPONSOR~

Oct 19, 2006

8,129

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Merrillville,Indiana

• Jan 24, 2009

• #10

I just have to agree, no way you can push that bike stock, to half its potential. Too bad about the suspension. MX Tech would fix it, period. I would rather have decent power and perfect handling any day. Bolt on power, pffft! Get the set up to remap it.