Bad scoring on Fork Leg (in slider) What caused this?

[Uncle Bob]

So got back from the MOT on Friday and the fork leg was leaking more than wanted, so striped down today to replace seal and the fork leg has really bad scoring on it and also the fork outer, internally. I have no idea what has caused this. I stripped them last year to have the fork outers power coated but cleaned and pretty sure they were assembled correctly - they certainly came apart with all parts correct and no extra bits found. The outer leg was blasted prior to powder coating and some "grit" left in leg was cleaned out with a high pressure water jet - inspected and all looked OK, but my only thought is was there some of the grit left somewhere I couldn't see and would it do this if so? Any ideas welcome as it's nice to know why something happened. Anyway I think the damage is so bad I am looking at new parts and will have to strip the other side down to check that as well now. It will mean no Katana for me at EK6

Click image for bigger version.

[callyboy]

Whow! That looks well fooked. Cant imagine how that happened.

Pete

[Nicky Dodds]

Never seen any forks scored that bad ever....tho I have led a bit of a sheltered life lol!

[Uncle Bob]

Yep, it is well fooked as you say and probably beyond repair.

The particles must have been hard as the fork leg grooves are quite deep. I just can't work out what has happened. I know during powder coating the part is heated up but not sure what temperature it is - it's couldn't go out of true due to that? The scoring is all on the back side of the fork and on the lower half. I'm thiniking it's something to do with the piston (image 3). The metal in the oil is what I think made the top oil seal fail.

I'll have to take the other side apart now as well just to check. Trouble is as I can't work out what went wrong, I start to doubt my own work.

[callyboy]

Was it powder coated then ? Maybe sandblast material?

Pete

[Uncle Bob]

I had wondered about sand blast marterial, but I did use a pressure washer to clean out the insides, unless it managed to get somewhere the water couldn't get to, but the only place possible would have been at the very top, just under the metal ring the seal sits on. I'm so hacked off about it as the stanchion was perfect before hand, and no Kat for EK6.

[stockcar]

almost definitely blasting media........

[fossie]

Yep gotta be last media, trouble with easing out with pressure is it forces ever ting to the bottom in the crevices , then when oil is introduced it frees up , moving about as grinding paste.

Best to have flushed them out with kero and a shaking action.
Feel for you! See you the weekend beer solves most issues ............for a while!

[Uncle Bob]

I'm coming to terms that it's blasting media. First time I have had the lowers done on any bike, In the past when I've taken the forks apart it's been for seals, so never had the issue before. I did check them well, but you can guess next time it will be surgical! I'm hoping the other side is OK. have found NOS leg and outer but it's going to cost me about £220, so lesson learned I guess.

So VStrom will be allowed then at EK6 or should I park in Swansea and get the bus?

[fossie]

We have a naughty corner for all non Kats!