Can anyone explain

[wjp]

Hi All,
Ok - I don't know too much about suspension, so please go easy one me!
I'm now trying to progress my jumping so that I clear the 40-50 foot jump at my local track. I'm try to work my way up to clearing the table, but I'm finding that my front fork suspension is always bottoming out, so I afriad not jump any further (only if I make the landing). Now I've got a stock 2002 250 YZ, and I weigh about 160 lbs. I believe that with this weight the stock suspension should be fine. Now I clicked up the suspension (at the bottom of the forks) up to about 17 clicks (20 in total) anymore and the bike becomes unridable in the rough stuff on the track. What can I do to stop it bottoming out - do I need more oil, different springs or what?
Any ideas are welcome.
thanks,
Wayne

PS the back suspension is totally fine..

 

[russ17]

First off ! I dont know your level of riding.I see alot of newer riders trying to jump table tops and flat land with the power off.If you would take a rock and hold your arm straight out and drop it into water it will go straight down and sink ( linier motion) but if you take that same rock and throw ( force) it at a angle it takes away most of the linier motion I feel that is what is produced when you land power on. might be your case might not. you might need a service, you would be surprised what cleaning and service can do for suspension. Also if you get a service have them check the mid-valve shims the have a tendancy to warp. for your weight you should be fine. you can also add 10cc of oil at a time to each leg to help with bottoming

 

[MikeT]

I think the landing with the power on comment is spot on. I would also look at your body positioning. Possibly you are too far over the front. Also the type/shape of the jump has a lot to do with how you land.

Are you experiencing this on all 40'-0" jumps?

 

[wjp]

yes its on most large jumps.
It could well be my riding style I suppose, as I'm not on the gas when I go for the jump, just take off with a steady throttle. Though I can't see how I can change this really otherwise I'll end up front wheel high.

 

[wjp]

just add that I do try and have the throttle on when I land - perhaps its not on enough!

 

[russ17]

Most of the fast guys like to have ther momentum up before the jump then adjust weather breaking off the face or excelerating ect. the other thing is when you dont quit make the table top most chop the throttle because they do not want to jump off the end of the landing .

 

[wjp]

so you concensus is that there's nothing wrong with the suspension, just my riding style?

 

[MikeT]

Originally posted by wjp
so you concensus is that there's nothing wrong with the suspension, just my riding style?

It probably is your riding style. Try this. When you are out at the track, look for a really good rider that is doing that jump well and tell him about the problem you are having. Ask him take your bike for a spin and see what he thinks about your suspension. If he thinks it's OK, then ask if he will watch you jump it and then ask him to comment on your position and style. Most good riders will help you out.

 

[russ17]

No! not my consensus just what I observe most of the time. If your suspension has never been serviced chances are that its do. but if you do have some issues with body position power delivery ect. then chances are your going to bottom out any way. I would take MikeT advise also.

 

[tchamberlain]

I have an 02 YZ250 too. You might not be bottoming. You might be "hydro-locking." From what I've been told the forks get too a point in the stroke where oil can't flow through fast enough and the fork kind of "locks." I weigh 185 and ride novice. I had my forks and shock revalved, set the compression at 10, rebound at 12, and oil level at 110. Forks felt great. I did eventually buy .44 fork springs to replace the stock 43. I then lowered the oil level to 125mm.

Also, are you at 17 clicks out from all the way in? That's lowering compression. Turn the clicker all the way in to the right (most compression), then turn to the left and count the clicks out. 11 clicks out is the stock setting.
Good luck.

 

[Buckholz]

RAISE the fork oil level!

 

[dirt bike dave]

I agree with Buckholz. Raising the oil level will dramatically improve bottoming resistance. Cheap and easy.

 

[marcusgunby]

first put a cable tie around the chrome fork leg and see how far it goes down on the hardest landings-if you are not using full travel reduce oil level(same as increasing the air gap)and or reduce compression damping.If you are using full travel then increase oil level(in 10mm increments)I generally try to get the plushness correct using the compression adjuster and then control bottoming with the airgap.

 

[wjp]

tchamberlain - its 17 clicks in..

MikeT - good advice. THe first thing I shall so at the track next weekend , is see if I can get someone to have a go. My French isn't great (I'm working here at the moment) but I'll give it a go. If not then...


Thanks for the advice guys - I think I might try the oil level.
Marcus - that's a really good idea - not thought about doing that. Just to comfirm - you saying that I should set the compression and rebound so that it feels good. Then do the tie trick to see if I need more/less oil to stop the bottoming ?

 

[marcusgunby]

Yes :)do the cable tie trick straigt away, i always have one ans set it before each race to see if im using full travel.
www.mx-tech.com has a tuning guide in the downloads section.