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forks too soft?

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Riding crf 450 -08. Suspension set up is pretty good, but I feel like I need to go softer with forks compression because of braking bumps. Problem is at local track always bottoming 1 table sometimes very hard. Looked other riders landing same spot and suspension takes it well.

Compression adjustment is 2 turns out.

Is revalving only way to go? Adding some oil, but that doesnt solve the brake bumps prob.

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how much do you weigh. You may need to re valve. If your under 215 You should be able to set it up with the clickers.

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the 08 has a terrible midvalve setup , they are always harsh

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According to Race Tech's Spring Calculator, you need .476kg/mm fork springs, which is what your bike comes with from the factory. What does your shop manual recommend? If you have a tuner close by, maybe he can verify the actual rate you have.

Do you know the recommend air chamber? I had a bottoming problem on my WR. The factory recommends 130mm air chamber. My tuner set it at 110mm but I found that even for woods riding I had to go the max 95 mm air and replace 5wt with 10 wt to keep it from bottoming on hard landings. That's 35mm less air than the factory recommendation.

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Damn, that sounds like an awfully heavy spring for a 180lb rider. If I were him I would check my sag numbers to make sure the bike is properly balanced. Damping is what absorbs the impacts. The springs hold the bike up in the stroke. Too heavy a spring and the bike won't turn. Too light and you will be riding too low in the stroke or running so much preload you will have a harsh ride. Adding oil and raising oil level in forks will help with bottoming and you could come off compression damping a click or two to help with braking bumps. That is if you have the correct springs per the sags. I find that spring calculators are usually wrong. Most of those companies WANT to sell you a spring

IMO,

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Default springs at front and rear. Race sag 105mm and free sag 35mm. Rechecking tomorrow.

So adding some oil would help? Dont know which oils are in because just bought the bike and last owner had them done in shop. He didnt remeber. I read mixing oils is ok? If adding some cc.

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It would be best to take the forks off the bike and measure your oil height (remove the springs and push the fork tubes all the way down). Check your owner's manual for the recommended air chamber. If the existing oil height is close to the recommended level, check your manual for the min air chamber, and split the difference. You can always had oil through the air bleed screw.

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you can't measure oil levels on tc forks

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The 07 was bad,the 08 is even worse. The comp damp is way to speed sensative progressive giving you the "mid stroke hash" feel on sharp bumps.

It cannot be fixed with oil hight. Re valve only way on this one. The springs are also too soft if your over 180lbs. Im 190 and needed .49s front 5.7 rear. This also helps with overall plushness as the fork doesnt compress as easly into last part of stroke. I know that sounds contradiction but slowing the stroke down a bit with stiffer spring means it doesnt slam as hard into high speed damp lock.

The Honda valving is too soft at beggining and too hard at mid. This not only rides harsh in breaking bumps BUT on slower speed stuff like big jumps it will bottom hard. Slower suspension speed not bike speed.

MX 1 did a good job on my 07. They eliminated the mid strke spike and got a overall well ballanced feel.

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Do as a few others here stated, go the next stiffer spring rate in the forks and drop the oil 10cc's from the stock amount, this will help a lot with the mid stroke harshness and also help with fork bottoming. After you have done this mod and if you are having probs with the corners, raise the forks in the clamps 5mm's this will decrease the rake and help with corning quicker. I would start with the comp and reb clickers in the stock postion and go from there. Be sure and check the sag for the rear.

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are you sure you are bottoming?

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lowering oil and adjusting clickers will do little on this bike. Not talking from theory here but experience. The magority of the harshness is due to overly progessive valving. No matter the oil height the valving will lock at higher speed movments.

Clickers also dont change the high speed damping enough to matter. They can have good effect at lower speed stuff but once the stroke speed is high the vast magority of damping is on the valve stack and its related circuit. On this bike its a brick wall.

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yea its bottoming ( o-ring at forks to show it). Going to try adding oil and turning comp adjusters softer and measuring race sag.

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try to measure fork sag ( not sure if that's what you meant) the 08 CRf fork is normally like a sx fork and doesn't bottom

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turning the clickers softer wont do much to mid stroke harsh thing. In fact it will likley make it worse as the first few inches of travel wich were too soft will now be even softer. This means it will slam into the mid stroke wall even faster making it feel harsher. Believe it or not going a little stiffer on the comp damp will give some , not much, but some relief as you wont blow through the first few inches of travel so fast.

adding oil can help with bottoming a bit as it effectively gives you a stiffer spring at the last few inches of trvel, BUT it can make the mid stroke thing a little worse too.

the 07 fork as it traveled through its stroke was like this....

too soft,too stiff,too soft

too soft in first few inches, too stiff in the middle, too soft again at the bottom.

This means it blows straight through the first half of travel, slams hard into the middle stroke, then blows through the last few inches.

This confuses people. How can stiff supercross like suspension bottom?? Its because it really doesnt have much to do with wher you are in the stroke. We talk "mid stroke harsh" , BUT its really high speed stroke harsh. Its just that usually it takes till mid stroke to get the suspension traveling that fast . At this point the valving is dominating the performance and the valving is like too small a hole for the oil to go through fast. It starts to hydrolic lock and feel very very stiff. MY 07 would literally blow my hans off the bars in some chop.

BTW measuring fork sag is super tricky. The damn seals and bushings have so much sticktion they never seem to settle in the same spot.

I had a thought the other day. I wonder if we should check sag with engine running? This to send vibrations through everything perhaps allowing the suspension seal sticktion to losses a bit and maybe get consistant reads?? Thinking out loud here.

Now the reasion this stiff suspension damping alows bottoming is that it really not stiff on the things that make it bottom because the suspension stroke speed is low. For instance my 07 was super harsh BUT it will bottom metal to metal in the forks in the valley between larger sucsession jumps. Theres a bunch of G force BUT slow suspension stroke speed so it never hits oil lock like at high speed suspension strokes like in choppy breaking bumps.

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Oil amount 375 and comp 2 turns open and its much better. Still stiff and brakings but I need to live with that.

Another question.

I've been riding sand track. Shock rebound only 3-4 turns open. Sag 104mm. Is there something wrong with my riding style or what because cant reduce rebound without getting back of the bike jumping side to side at medium size high speed bumps.

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its because its too stiff, rebound adjuster has just as much affect on the compression to the point where the bike is moving instead of the suspension

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