Sag questions - Bottoming Out

[revitup]

Beginner here...3 total rides. First couple of rides, I just rolled over jumps. I started jumping small jumps (2'-3') on the third ride. Then I started a bigger jump (to me), takeoff slope maybe 6 feet long then slight down slope. I hit it standing up, got a about 2 feet of air, landed down and both the back and front shock bottomed out smacking both fenders. Scared the heck out of me. Almost lost my footing slamming down. Anyways, at that point, I knew I needed my suspension checked....I began by checking the race sag.

1. How far can I tighten the preload spring? My first measurement for race sag was 4.5" (recommended was up to 3.9, 2001 YZ250F). I turned it 3 full turns and it didn't do much. I have since turned it 8 full turns. Still over an inch of thread to keep turning it.

2. Does it matter about how much you can pull the bike upwards when the bike is on the ground? With the bike on the ground, I grab the seat and pull the backend up. It only comes up about 1/2". I thought I read somewhere that it should be at least 15mm (which is more than 1/2 inch)?

3. Should I not be worried about this upward pull measurement and just worry about race and free sag?

Once I get the sag set what 'clickers' should I use to prevent bottoming out or could I possibly need stiffer springs?

gm
6' tall, 185 lbs with gear on.
2001 YZ250F

 

[jzyz]

Did you buy the bike new or used? If used, did the previous owner have anyhting done to the suspension? It does sound like it need springs to me. Also if you have the proper amount of sag 3.5-4 inches or so while on the bike, you should have about 15mm when you pull up on the seat, having less than that is an indication of to light of a spring. I don't think that you what to control bottoming with the clickers, they are more for slowing or speeding up the shock or fork action to obtain the best ride for overall conditions.

 

[yz_387]

Your springs may not be exactly correct for your weight, but I don't think they are really the source of an extreme bottoming problem. I am about 160 lbs or so with gear on, and I have no bottoming problems on the exact bike you are riding even over 75 foot plus jumps. You said you are a beginner, so I assume you have done very little jumping. One thing you will find is that often hitting a jump slowly and flat landing will hurt more than hitting it fast going farther and flat landing. This is because the forward momentum helps absorb the impact. If you are jumping up and not really traveling forward, it is very hard for your suspension to absorb the impact. You may find that as your jumping skills improve and you are able to jump bigger jumps and time the landings properly, you will not experience as much of a bottoming problem. If you do want to adjust the clickers to help, you will gain bottoming resistance by turning in the low speed compression clickers. To find out what the correct springs are for your weight, go to the mx tech websight and use their spring rate generator. Good luck.

 

[revitup]

Yes, I bought the bike used. The dealer said the previous rider was about my weight but shorter. I'll have to find out if anything was done to the suspension when I go back to the dealer. There are stickers on both the front and rear that say ProCircuit. I don't know what the stock front and back shocks are suppossed to be or if the stickers were added just for design.

Since then, I called the dealer and am going in to have them check it out. I had my wife video tape me bottoming out. Race-Tech said the recommended rear shock for me is 4.944 kg/mm. Does this mean I need a 5.0 spring. The stock spring was 4.8. It says the Ideal Rider Weight for the Stock Spring is 160lbs which is about 20lb off.

>>You said you are a beginner, so I assume you have done very
>>little jumping. One thing you will find is that often hitting a
>>jump slowly and flat landing will hurt more than hitting it fast
>>going farther and flat landing.

This is true. I roll over most of them and pick a couple that I'm working on. After reviewing the video tape, I am going pretty slow.

I'm taking the bike in Friday to have a racer/mechanic look at. Thanks for the replies guys...gm