Mar Forks

[bashplate]

Ok guy's,

got a 250 Mar here with leaky fork seal (apparently) and bottoming out alot. On strip down the seals were immaculate with as new edges on the 'scapers' and the dust covers gripped the stanchions good. Stanchions good fit in the sliders, with clean ATF drained from them, though a minimal amount due to leakage. Just guessing here (not my bike) but looks like the oil had got past the seals and then trapped between them and the dust covers....then to the out side world. SOOoooo, would excessive compression tying down on a trailer force the oil past the seals??? or is there some other scenario which would explain how tiptop seals would leak? Any tips for improving while I'm in there like oil grade or damping hole modifications? springs are 19 inch long no spacers...the other posts I've seen say 17 inch is that with spacers?

Cheers, Trev

[woody]

Are you sure they are proper fork seals and not rotary seals? Why ATF? Use 10W fork oil. May be a combination of rotary seals and ATF that's letting oil through?

Otherwise, no idea on that one, if there is no apparent damage to the stanchion surface that would let oil past. Can't see strapping it down would cause it, the oil should just flow through the damper rod. It's really hard impacts that burst seals.

MAR forks work pretty well without any mods from my experience. The standard springs are good, if they aren't worn or sagging. You can't say specifically what length spring is required as it depends on the spring being used, so 17" or 19" would both work if they are a correct rating.

The bottoming will be due to low oil more likely than the springs. I'd replace with proper fork seals just to be sure (1 of 35 x 47 x 10 in each leg) fill with 180cc of 10W oil and try again and see what happens.

[lbhbul]

Trev, A little trick taught to me not too long ago that really helped,

Using proper fork seals!!! Before installing, take the seal spring out & un screw it and cut 1/4 inch from FEMALE end & screw it

back together & re install spring. Now you are ready to re seal.

Have a nice day (edit female)

Larry

Edited December 11, 2014 by lbhbul

[b40rt]

Should always try cleaning them first, you can make a similar tool easily.

http://m.youtube.com/watch?v=1owBoyM-i3k

[bashplate]

thanks guys. the chrome is perfect and there's 3 seals each side....from my understanding there should be 2 each side with a spacer between them??? how can you tell if seals are roundy round or up and down ones? they all 35x47x7 but 'outer' ones are blue...tothers are black.

[woody]

Standard there are two seals per leg, I can't remember the actual thickness of them now, but probably 5 or 6mm . There is no spacer between them.

I only use one 10mm thick seal, same size as for the KTM SX65, so if you buy a genuine KTM seal you know it should be good quality.

Not sure if the seals have identifying markings as to whether they're rotary or hydraulic but any seal distributor should know. I believe rotary type can leak quite quickly if used in forks.

[bashplate]

thanks woody, will check out the seals