Jump to content
Sign in to follow this  

shock preload and gas question

Recommended Posts

Hey all. Question about the shock. Just got an 04 yz250 and all this new technology is fantastic. Last bike as an '80 CR250, yup, I am old!

I am 6'4, 280 and this shock is stiff as a board!! Hardly compresses with ME! I backed off the spring tension, that helped a little. Got a wild hair to check the N pressure. I now, I shouldn't check since the vol. is very low in the bladder, bt did it anyway. Touched the needle with a nail, had hardly and pressure. A quick touch on the needle, it sounded like about 3-4 lbs. Noting like what I ahve read here or what the manual suggests. Most of you like 140-150 lbs of N pressure...should/could I go higher for my size? I don't jump much, well not yet. Mainly woods stuff.

Oh, and that seat...kinda hard on "Big Jim and the Twins"

Guessing a charge should be about $5 or so?? Might sneak some out of the welding shop.

Share this post


Link to post
Share on other sites

Without a zero loss chuck, you can't check the shock pressure because it will be at least 10 lbs less than what you read due to the loss. Anyway, there's not much volume in there, so a quick touch of the needle can let out most or all of your nitrogen. So you need to fill it up, but I think you have other issues. First, check the compression adjuster to see that it's not all the way in. If that's OK, then I would suggest rebuilding the shock. The heaviest spring you can normally get for that bike is a 6.4 or 6.6 which is about right for your weight, so you should definitely be able to compress the shock, especially with a low nitrogen charge. If you can't, there's something else wrong.

Share this post


Link to post
Share on other sites

I can compress the shock but it feels like a lot of spring tension. I keep backing off the nut only 2-3 threads at a time.

I do plan to get the shock charged and while it's off, will back off the spring even more.

the kid who had it weighed about 150 (about what my right leg weighs), and the spring was almost at the end of the threads, tight. What was that boy thinking???? It is getting softer, guess I am not that bad of shape. the N charge will help. All in learning. Will get the book out tonight and back off all the settings when the shock is out, all back to factory 0 and go from there.

thanks for the input!

Share this post


Link to post
Share on other sites

It takes a lot of turns to change the spring preload a significant amount. Also, that Nitrogen pressure does not do as much for stiffness as it sounds like it does, or would.

Be sure and check the compression damping screw....Thats the top adjustment, near the reservoir. The flat head screw in the center, probably made of brass or aluminum.

Share this post


Link to post
Share on other sites

You may need to put 150psi of air in,"temporary", till you get nitrogen.

So that the rebound needle will get seated as it can affect your compression as well.

If you take the spring off then with the clickers mid-way, you should be able too push it in easy enough and it should come back out on its own.

Did you check all bearings, maybe frozen?

Share this post


Link to post
Share on other sites
Did you check all bearings, maybe frozen?
Good point :smashpc:. I can't seem to get one season out of a lower shock bearing. I got 5 bucks says yours is toast.

Share this post


Link to post
Share on other sites

Thanks all, going to tear into the shock tonight or tomorrow if I get time. You are right, it the brngs are seized, I am FUBAR for sure. I have seen kits for this all the time, must be a common problem.

Since I am not racing, just playing and checking fences, I may go the 150 lbs of air for a while till I get to town to get the N.

While I have it off, I thing I will go through/over the full suspension, swing arm brngs too. Hard telling how that kid took care of things, (or didn't take care of anything). Just did the front from the Triple tree, fork rebuils, wheel brngs, brake pads, and seals. Did the back wheel brng and seals too with both new tires/tubes. Finished the clutch check last week, did the carb a week ago with reeds.

Hell, why didn't I just build the stupid thing from the ground up??!!

Oh, well, at least I will know where I stand on maintenance will help resale too.

thanks again.

Share this post


Link to post
Share on other sites
Good point :smashpc:. I can't seem to get one season out of a lower shock bearing. I got 5 bucks says yours is toast.

Yup, you were right! I took out the spacer, needles all rusted, sprayed with WD, put little finger in to try to spin them, they broke and fell out! Guess I am off to town tomorrow to get a lower brng. which the local Yam dealer will not have! GRRRR!

Shock had no N in it. Local tire shop I deal with a lot charged it for me, FREEBEE, was insulted when I tried to pay for it! They will get more of my business later anyway.

Shock works fine, no leaks, spring was cranked all the way down tight. Not now. Have to read the manual on the settings now too.

Thanks for the info !!!

Share this post


Link to post
Share on other sites

Those bearings have no housing and will fall out..odd, but true. Often times you can clean the rusty stuff off and find them ok.

Share this post


Link to post
Share on other sites
Those bearings have no housing and will fall out..odd, but true. Often times you can clean the rusty stuff off and find them ok.

This one did fit in pretty snug but the needles fell out of the cage and most were broken, as in half. Part of the outer cage was broken too. I wonder how long this had been bad. Fixed soon, and repacked with waterproof grease. Learned that the lesson a long time ago.

Share this post


Link to post
Share on other sites
This one did fit in pretty snug but the needles fell out of the cage and most were broken, as in half. Part of the outer cage was broken too. I wonder how long this had been bad. Fixed soon, and repacked with waterproof grease. Learned that the lesson a long time ago.

even the new bearings will fall out.they have no cage(i don,t get why they do that?).be careful with the new one,s.

Share this post


Link to post
Share on other sites
even the new bearings will fall out.they have no cage(i don,t get why they do that?).be careful with the new one,s.

I see what you are talking about. They are not "locked" in the race at all. Will repack it with waterproof grease and throw in the freezer before installing them.

Share this post


Link to post
Share on other sites

Suspension update: Got the shock recharged with N, rebuilt both ends of the shock, polished all the piviot bolts, coated with waterproof grease, backed off the spring about 1". Now about in the middle of the total threads. Figured that is a good place to start. All setting back to factory settings.

WOW what a difference!! So smooth and responsive!! Not sure what made the most change but it all works great, now. Thanks to all who offered their help!!

New front brakes. Went with the metal sintered and tool off carbon fiber. Massive stopping power now!! at 6'4" and 280, I about launched over the bars the first time I grabbed a hand full of brake lever. Locks up the brakes very easily!!

Pro Circuit pipe to go next if it ever gets here. I am beginning to think this is more bike that I can handle. My last MX bike was a 1980 CR250 Elsinore. What a difference!

Thanks again to all!:smashpc:

Share this post


Link to post
Share on other sites
I can compress the shock but it feels like a lot of spring tension. I keep backing off the nut only 2-3 threads at a time.

I do plan to get the shock charged and while it's off, will back off the spring even more.

the kid who had it weighed about 150 (about what my right leg weighs), and the spring was almost at the end of the threads, tight. What was that boy thinking???? It is getting softer, guess I am not that bad of shape. the N charge will help. All in learning. Will get the book out tonight and back off all the settings when the shock is out, all back to factory 0 and go from there.

thanks for the input!

I love your humor. Representing the big riders hauling :smashpc:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...