Forks won't bottom out

T-Dawg156
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Wilsbach DE

I recently had the chance to get my hands on a 23 crf 450, used in the world Championship. The bike had seen about 20 hours under a about 80 heavy pilot. I am a B  class front runner, and do have about 100 kg without clothes. So the point is my shop guy/ the Team owner said it would probably be just right when you consider the weight and Speed difference. Man... it is not! That thing is brutal! The engine rips your arms out of the socket and this fork just doesnt move. I tought i would figure it out at first, but i think i have to re think things, considering racing season is just around the corner.

So: i actually played around with it a lot, and are now running about 330ccm of oil. I still do have about 3 cm space before bottoming those forks out. I feel the friction is pretty high too. Rebuiled them about 2 hrs ago, it didnt help. The production forks are still on, just reshimd. I ride them with 5.4 springs. Compression out 10, rebound out 15. when i go further out on compression, it feels even harsher. Only riding hard pack. So right now i think iam working in the upper 2/3 of the stroke, and not touching the last bits. those forks are so hard, we didnt even get the starting device engaged trying our hardest with 3 grown man including me (with 1,96cm) also not the smalles guy.

how the fuck do i get those things softer? Even less oil? Dont have the money right now to get them re-shimed right now...

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4/17/2024 12:26pm

Make sure the forks are aligned and clamp bolts are torqued.

You'll probably benefit from softer springs (Race tech recommendation is .51kg/mm)

You probably need revalving too, but you might be able to save some money if you get the correct springs and it rides fine.  

Once you get the forks working good you'll probably notice the shock is too stiff for you.

3
aees
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4/17/2024 12:39pm

Drop the oil further. Not unlikely they run a spring perch or tube that is very aggressive. 

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MxAddic
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4/17/2024 3:00pm

I am thinking they are overdamped for you style/speed.

I would try less oil down to the min. if needed..

T-Dawg156
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4/17/2024 9:26pm

The manual states 330 is the minimum, how low can you go wiithout running in to problems?

The Shop

T-Dawg156
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4/17/2024 9:29pm
3strokemx wrote:
Make sure the forks are aligned and clamp bolts are torqued. You'll probably benefit from softer springs (Race tech recommendation is .51kg/mm) You probably need revalving...

Make sure the forks are aligned and clamp bolts are torqued.

You'll probably benefit from softer springs (Race tech recommendation is .51kg/mm)

You probably need revalving too, but you might be able to save some money if you get the correct springs and it rides fine.  

Once you get the forks working good you'll probably notice the shock is too stiff for you.

Race tech recommends 5.4, so the Springs should be fine. Kg not lbs. I alays make sure everything is aligned and torqued properly

aees
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4/18/2024 1:50am
T-Dawg156 wrote:

The manual states 330 is the minimum, how low can you go wiithout running in to problems?

Its a bandaid reducing oil, but it helps. Not sure what happens if you go below, not enough lubrication in fork? Not sure.

You need to get it revalved.

T-Dawg156
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4/18/2024 4:05am

The oil isnt filling the fork top to bottom anyway, the cartridge is filled completely independend of the outer tube. So theoretically i can go as low as 290 or so right?

MxAddic
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4/18/2024 4:43am Edited Date/Time 4/18/2024 4:44am
T-Dawg156 wrote:
The oil isnt filling the fork top to bottom anyway, the cartridge is filled completely independend of the outer tube. So theoretically i can go as...

The oil isnt filling the fork top to bottom anyway, the cartridge is filled completely independend of the outer tube. So theoretically i can go as low as 290 or so right?

You should be OK to do so but I wouldn't go any lower than that. If you are at the min. it's a safe bet you would benefit from a re-valve.

obiwan461
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Cypress, TX US
4/18/2024 4:58am

Oil isn’t the problem it’s way over sprung for you.  If it’s truly GP bike sounds like it was sprung and valves for Jeffry Hurllings. Sounds like you could flat land a 80 ft table over jump

by 20 yards and you won’t crash. Just make sure your fillings in your teeth aren’t loose.   The dr and your suspension tuner are the two men you need to be very Honest with.  I worked for  JM racing years ago and guys would come in and tell me they are pro level ect and I knew exactly how these kids were really mid pack novices.  Because I rode and raced every weekend.  We just used race tech springs and 3 different cookie cutter shim stacking  profiles they have. There’s stiff fast guys. Mid pretty much every one but slow novice and beginner and soft. For vets to make it plush. Now thaf I’m old vet but heavy I like spring heavy valves plush. 

CodyC
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Morgantown, WV US
4/18/2024 5:01am

Are they bound?  Try putting the bike on a stand, loosening the triple clamp bolts a bit, take the bike off the stand bounce it and then torque them back down.  While you're at it I'd check your height above the triples to make sure they are equal.

 

I'd give that a shot if you are getting stiction or weird feedback trying to test them in the shop.

T-Dawg156
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Wilsbach DE
4/18/2024 5:57am

The race tech guide states 5.4 for my weight, and i have 5.4 in there. How can it be that it its so over sprung?! And with the minimum amount of oil in it, i really wonder how that thing is still as hard as an german eiche ( the hardest tree which is growing here)

MxAddic
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4/18/2024 8:37am Edited Date/Time 4/18/2024 8:40am

I don't think it's a spring issue. I can't see him running .54 springs. That's what the top SX guys run. Maybe have them tested.

1
T-Dawg156
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4/18/2024 9:13am

Do i get something wrong? Type it in at race tech and you get .54 out of it

MxAddic
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4/18/2024 9:27am
T-Dawg156 wrote:

Do i get something wrong? Type it in at race tech and you get .54 out of it

I don't trust their calculator but maybe they have improved it. At your weight going up 3 rates sounds reasonable. If you think the springs are too stiff for you they may be.

4/18/2024 11:13am
T-Dawg156 wrote:

Do i get something wrong? Type it in at race tech and you get .54 out of it

image-20240418140606-1 If you select 0-29 age range they recommend the .53. 
The only way I think they would factor in age would be experience/maturity relating to better line choice. I also assumed German tracks have more chop and less SX inspired layouts, which made me think the .51 was a better match anyway.

My experience with the Race Tech estimator is that it is a really good starting point. I've used their valving suggestions and gold valve too, and it's been really good. Not as good as some A-Kit Enzo stuff I got to try out, but that setup was a little out of my budget.

aees
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4/18/2024 3:33pm

Did you get them with 5.4 springs? If not, my guess is that valving is stiff because of previous riders speed. Adding stiffer springs to that for your speed would make them feel like you describe. 3cm is not a lot left.

So get them revalved or drop to 5.2.

T-Dawg156
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Wilsbach DE
4/18/2024 9:45pm

I got the bike with 5.6 in there, those fast belgium guys are crazy...

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