Which fork oil?


23 replies to this topic
  • red7

Posted March 08, 2007 - 09:45 PM

#1

I'm making a trip home to the States in a few weeks and want to stock up on parts and fluids for the bike. I have an '06 YZ450 that needs it's fork oil swapped out so I'm curious what you guys are recommending. In researching motor oil it seems that Amsoil is as good as it gets so I'm curious about their shock therapy fork oil as well. If it's good I could add that to the cart before placing the order for the engine oil. Grayracer, I know you're big on their motor oil....are you using their fork oil as well?

Thanks!

  • grayracer513

Posted March 09, 2007 - 09:04 AM

#2

No, but apparently, it will work. I've resealed 3 '06 forks, including my own, and used Maxima Light Shock Fluid (3wt). Everyone likes it.

There's been a lot of discussion about this:

http://www.thumperta...ad.php?t=472632

http://www.thumperta...ad.php?t=473979

http://www.thumperta...ad.php?t=473085

  • SXP

Posted March 09, 2007 - 10:20 AM

#3

Gray - What oil do you use in the rear shock? The same 3W Maxima? Thanks.

  • grayracer513

Posted March 09, 2007 - 11:05 AM

#4

Haven't changed the shock oil, but as of now, I would probably use the same Maxima, yes.

  • Pincushion

Posted March 09, 2007 - 01:11 PM

#5

Haven't changed the shock oil, but as of now, I would probably use the same Maxima, yes.


At how many hours do you plan on changing the shock oil? I know it doesn't contaminate as quick as the outer fork oil, but I'm curious how long you let it go.

  • red7

Posted March 09, 2007 - 04:02 PM

#6

No, but apparently, it will work. I've resealed 3 '06 forks, including my own, and used Maxima Light Shock Fluid (3wt). Everyone likes it.

There's been a lot of discussion about this:

http://www.thumperta...ad.php?t=472632

http://www.thumperta...ad.php?t=473979

http://www.thumperta...ad.php?t=473085


Thanks!:applause: As always I had done a search but didn't come across amsoil specifically when I searched "fork oil" in here so I thought I'd go ahead and post. It doesn't sound like their fork oil is anything special like their motor oil so I'll go ahead and order up some Maxima.

BTW- I know that I should probably up the volume of oil by 5cc since I've been having some problems with bottoming out. Does 3 vs 5 wt (or other) have an effect on this as well? If so, please explain.

Thanks again everyone!

  • grayracer513

Posted March 09, 2007 - 04:13 PM

#7

3 to 5 wt isn't much different either way.

This may help:

http://www.thumperta...475#post4433475

  • N2Roost

Posted March 10, 2007 - 09:22 PM

#8

BTW- I know that I should probably up the volume of oil by 5cc since I've been having some problems with bottoming out. Does 3 vs 5 wt (or other) have an effect on this as well? If so, please explain.

Thanks again everyone!


You won't notice a difference between 3 to 5W. The oil level only affects the last 1/3 of suspension stroke.

You didn't say how much YOU weigh. If you're over 170 -180 stock springs are not heavy enough and you will need EXPERT suspension setup/service.

  • moochie

Posted March 11, 2007 - 06:11 AM

#9

You didn't say how much YOU weigh. If you're over 170 -180 stock springs are not heavy enough and you will need EXPERT suspension setup/service.


Based on the spring calculators on the Race Tech and MX-tech sites and my own personal experience, I don't believe that's true. Stock 2006 YZ450 springs should be just about right for someone who weighs 170-180.

  • N2Roost

Posted March 11, 2007 - 02:28 PM

#10

Stock 2006 YZ450 springs should be just about right for someone who weighs 170-180.


ASTOUNDING.

If you're [COLOR="Red"]over[/COLOR] 170 -180 stock springs are not heavy enough...



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  • moochie

Posted March 11, 2007 - 08:09 PM

#11

ASTOUNDING.


If you're over 170 -180 stock springs are not heavy enough...


Astounding?? :applause:

If you were playing horseshoes, a 10 lbs range might work for you.

If I'm 175lbs do I need stiffer springs? How about 181 lbs? Stock springs are ok all the way up to 185 lbs unless you're racing supercross.

  • red7

Posted March 14, 2007 - 12:29 PM

#12

I weigh 180. I'm thinking the last 1/3 of the stroke is where I need some help as I have to have the compression clickers turned in pretty far so that I don't bottom out but then I noticed that I lost the nice smooth action in the braking bumps. Our SX track doesn't get groomed much except for before races so it does get chewed up but thankfully no ruts since it's sandy. It's free though and the best track in Mexico...plus it's 2 blocks from my home so I can't complain.

  • N2Roost

Posted March 15, 2007 - 03:43 PM

#13

I weigh 180. I'm thinking the last 1/3 of the stroke is where I need some help as I have to have the compression clickers turned in pretty far so that I don't bottom out


Yep, probably compensating for slightly too soft springs for your weight. A good suspension shop should give you advice on the best price modes to try before buying new springs.


....but then I noticed that I lost the nice smooth action in the braking bumps.


Yep, and your high speed circuit needs setup.

You can mess with it for a year and maybe never get it all right... or have a tuner set it up just for you and feel like you've got a new ride.

  • red7

Posted March 16, 2007 - 08:36 PM

#14

Yep, probably compensating for slightly too soft springs for your weight. A good suspension shop should give you advice on the best price modes to try before buying new springs.




Yep, and your high speed circuit needs setup.

You can mess with it for a year and maybe never get it all right... or have a tuner set it up just for you and feel like you've got a new ride.



I'm still farely new to dirtbikes so I'm still figuring all this out but the frustrating thing is how much the suspension seems to change. The bike has about 25-30 hrs on it and I've been told that the fork oil is worn out and that is the reason i've started bottoming out and have not been digging my suspension like I did before. Brand new it was stiff and then about 10 hours into riding it was unbelievable and I knew exactly what people were talking about when they raved about the '06-'07 suspensions. Then at about 20 hours it's like someone took out some fork oil or dropped in lighter springs as all of a sudden I started bottoming out. Over the last week I've turned in the compression clickers 5 clicks (I'm almost all the way in now) and it hasn't stopped the bottoming (it has reduced it) but now it's rock hard on the smaller bumps.

Your comment about having someone set it up properly sounds good but I'm worried that every time I have the fork oil changed (sounds like 20 hours is the limit) I'm going to go through the same cycle where I love the suspension for a handful of hours but then it drops off quickly. In 2 weeks I"ll be going back to the States and can get the oil changed so hopefully that will take care of it and I'll get my great suspension back!

  • grayracer513

Posted March 16, 2007 - 10:36 PM

#15

Your comment about having someone set it up properly sounds good but I'm worried that every time I have the fork oil changed (sounds like 20 hours is the limit) I'm going to go through the same cycle where I love the suspension for a handful of hours but then it drops off quickly. In 2 weeks I"ll be going back to the States and can get the oil changed so hopefully that will take care of it and I'll get my great suspension back!

To some extent, this is brought about by break in, and that's done. A lot more is due to the stock KYB fluid breaking down, which it apparently does rather more quickly that most of the commercial replacements that have been mentioned.

  • red7

Posted March 17, 2007 - 09:23 AM

#16

To some extent, this is brought about by break in, and that's done. A lot more is due to the stock KYB fluid breaking down, which it apparently does rather more quickly that most of the commercial replacements that have been mentioned.


Yeah that's true the break in should be done so atleast that variable is out of the equation. So it sounds like if I can stiffen up the last 1/3 of the stroke to keep it from bottoming I could then back off on the compression clickers so that I get the smooth action back in the rest of the stroke. Is it correct that increasing the volume of oil by 5-10cc is the correct adjustment for the last part of the stroke? Sorry to have you guys repeat this but I want to be sure I understand what adjustment effects what part of the stroke.

BTW- so far I've really loved how my shock (and the rest of the bike) handles so my only issue is getting the forks dialed.

Thanks for your guys help!

  • red7

Posted March 18, 2007 - 06:13 PM

#17

As I mentioned I'll be changing the fork oil (or even have the forks reworked by a shop in AZ) when I go back to the States at the beginning of April. In the meantime, is it possible to add a little oil in 5cc increments to see how it helps the bottoming out even though we already know the fork oil is shot? One of the veteran riders at the track today said that I could open the air vent on the top of the forks and then add some oil with a syringe. Is that correct that those vents lead to the outer fork oil? Do I have to worry about mixing different weight oil or will it not make a big difference for the next few weeks? He has a little 15 weight oil that I can add and recommends I go to 15weight oil when I change mine so I'm curious what you guys thing about that.

My main objective is to get it somewhat rideable between now and my first SX race (first race in period) which will be on April 1-2. My issue is that even if I land the 60' triples perfectly I'm still bottoming my forks mainly because of how high the jumps throw you and because 2 of them have fairly flat landings. If I crank my compression clickers all the way in then it only bottoms out if I over or under jump the triples or the big table top so it's ok as far as that goes but then it's really, really, stiff over everything else and even just landing a small double rattles my hands so that I get arm pump faster.

I'm probably going to bite the bullet and have the whole suspension redone in April as it seems 180 is just a little to heavy for these bikes but I need your help bandaid fixing it until after the race.

Thanks!

  • Ranger18

Posted March 19, 2007 - 07:00 AM

#18

I don't meen to hijack this thread, but maybe this question will help people when they go to service their suspension.
Has anybody used or heard of using ATF trans fluid in their forks? I've heard it doesn't break down as fast, and it out performs standard shock fluid. Is Any of this true?

  • grayracer513

Posted March 19, 2007 - 08:20 AM

#19

Most current ATF's are extremely durable fluids, and can work well in most forks. In fact, since they are built as gear lubricants as well as hydraulic fluids, one of the specified requirements is shear stability equivalent to API GL-1 gear oil (75w-90). The synthetics, like Mobil 1, are usually a better choice because the viscosity index is better, and there's less change in viscosity through the temperature range due to that. They foam very little, lube very well, and hold up very well.

But so do contemporary fork oils. In fact, some of them have viscosity indexes that exceed ATF's, making their performance in valving even more constant as the fork or shock heats up. Plus, ATF works out at about 7wt, which is a little on the heavy side for most of the newer forks. The '06+ fork should have oil between 2.5-5wt. I have used Dexron III in '03's and '04's, and while I liked it in the '03, I didn't in the '04, and went back to a 5wt.

IMO, you can try it, and if you like it, it's a low cost, high quality oil that will hurt nothing to use, but I think you're better off with a good modern light weight fork oil, at least in the newer bikes.

  • red7

Posted March 19, 2007 - 08:57 AM

#20

Hey GR, you got any input for my situation as per my last post? I'm especially curious if that guy was right about being able to add fork oil through those air vents on the top of the forks with a syringe. Based upon your last post I realize that newer forks don't like the higher weight oil so it would appear that his recommendation of going to 15 wt is not correct for this bike. He rides a 06 KX450.

Thanks!





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