250-500cc 50mm Marzocchi bearings

G'day all, is anyone able to tell me precisely what the proper bearing clearance should be for 50mm Zokes. I refer to the upper and lower Teflon lined bushes. I am aware many people have had some issues with these forks leaking regularly. I can vouch for only the last 20 hrs of ownership on mine. Recently one of mine began leaking a little oil, when I removed the front wheel and applied a fore and aft motion to the lower fork leg, there appeared to me to be excessive movement, which measured to be .006" at the lower bush on one leg and .004" on the other. The six thou one was leaking, the other not. Placing a .002" shim under the upper bush seems to have removed the play from those, without causing any binding. It would be nice to know what the correct free play should be, which might stop the ongoing leaking problems people have. Oh, and I did the measurements with new bushes installed. The old (leaking seal) bushings had .008" and .006" clearance respectively.

(edited to correct "smart phone-isms" during drafting)

Hmm, perhaps someone can provide their experience of what clearance they have found to prove successful at prolonging seal life, and what they did to alter the clearance ? Any feedback will be appreciated. Thanks in advance.

I did notice that the open chamber 50s have some play like you describe but I never measured it.

My secret to preventing leaks is to switch to the skf seals. They advertise less stiction but i didn't notice a difference but they have lasted about 40hrs at this point.

I also clean the tubes of any dirt after washing.

G'day Uranys, thanks for your feedback. I had heard of using the SKF seals, good to get some idea of their performance. I also try to keep my fork legs as clean as practically possible. Done 6 hrs on the new seals, no leaks so far. Will try the SKF's next time and continue the pursuit of reducing the play also.

My factory seals (09 WR250) started leaking at pretty low hours. I went with SKF seals 3 years ago and they are still holding. The SKF seals also have less stiction and the forks work better on the small stuff. I'm not sure about the clearance but I do know that bigger tubes like 50mm need more clearance then say a 43mm.