I am having difficulties with my newly rebuilt kx forks. I was riding today and took a break and noticed a clanging noise coming from the right fork and a lack of/weird damping characteristics. Well what could that be (I already knew)? The cartridge rod had removed itself from the top cap, not just unscrewed but all threads gone, and destroyed those plastic pieces that go right below it.
I had a local mechanic rebuild the forks and I don't think he would've tightened the jam nut enough to pull those threads out. The only thing I can think of is a previous owner messing with the forks and messing the threads up. Or possibly jam nut came loose and pulled threads out. The only mechanical change I made to them since getting them back is added 20ml oil to each side which wouldn't cause this issue. So now I am trying to source a cap and plastic bits to fix this myself.
Also the rod has no compression damping until 3/4 ways down. Is this normal? I didn't check the other side since it was still assembled. When I got the bike initially it took the guy a while to get them rebuilt because the compression valves in the bottom were leaking and were not factory, looked like some weird aftermarket deal from way back.
please help.
An easy problem to solve...
https://www.ebay.com/itm/166367355000
Unfortunately I'm not trying to buy a whole nother set of forks and seals to rebuild them. Will the top caps of another bike brand 46mm forks work? Yam and Honda and possibly Suzuki all used 46s at one point. I found the plastic guide pieces on the bay.
The fork cap off a 1997 YZ250 should fit, but you will struggle to find any, you would be better buying another set of forks, at least you will have spare parts!
I ended up ordering another set. Is there a write up or something somewhere on cartridge forks so I can better understand the operation. I have them almost complete tore down, cartridge and base valve still together. Lots of plastic bits so will need to take base valve apart.
The Shop
The 1997 KX250 has open cartridge forks...
Question before I put this back together. The base valve (the one at the bottom with the hex and comp adjustment), do I need to remove some peening before I take the nut off to disassemble? I want to make sure there's no plastic bits in the valve or shim stack.
I am using a cartridge from the new set of forks instead of disassembling mine to clean it. I read somewhere there's some seals in there that "cant" be replaced. Is this something to be concerned about? I'm going to disassemble this cartridge anyways for curiosities sake. I read about some peening, is that the 4 holes in the top I can see threads through?
The guy who did my forks said he set the oil height at 139 mm due to the stiffer springs, that would explain why I had to add 20mm oil to each side for bottoming resistance. I plan on filling to 139mm (5.47"), then adding another 20mm. I do this with the fork FULLY compressed and cartridge rod in all the way correct?
When I broke it down it pulled the tube out of the seal. It doesn't LOOK damaged, plan on reusing. I used a plastic sticker to get it over the square edge installing it. I have a 48mm driver. I assume that's not gonna work so I plan on using some tape to protect the leg and just going in old fashioned with a punch.
Perhaps a good idea would have been to have a suspension shop service and set up the fork to your weight and terrain. After this, then take over servicing.
They have a trained eye for worn parts and nothing is better than a personalized set of suspenders.
now to make things more fun and confusing. The cartridge I pulled out of the new forks is different than the one I removed from the originals. So it looks like I'm using the original. When I took the base valve apart to clean the plastic out the shins were oily and I got them mixed up and reassembled based on the wear markings, it looks like a different stack than the one I pulled from the new forks.
Now to answer my previous question I think the original carts have been torn into since the new ones do not have the peens drilled out. So we will see how well it comes apart since I will be reusing the original.
No doubt, shop services are excessive period. Even more so in relation to old bike value. I dropped almost $800 on my old '06 SX suspension.
I just thought you may be tearing down too far for a bushings replacement and oil change.
Good luck
I got them back together without much issue, set oil height @ 135 and added 20ml to try and match the left side. It was not leaking when I reassembled and put it on the bike.
They do not seem to have enough rebound damping but I already had the rebound almost maxed and have the stiffest springs they put on the shelf (.48) so it is more likely related to that. Only 4 shims on the rebound stack iirc, obviously not gonna try and change anything unless I know what I want to change and that would require actually riding the bike. But I have a much greater understanding of cartridge fork operation now and hopefully have good luck with the fork.
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