Mirage 1200 Marzocchi fork oil change

mkavci9

mkavci9

Full member
Location
Slovenija
Hello,

I searched a lot on forum and net and I haven't found any good guide how to change fork oil on my Mirage 1200 TS, year 1982.
I'm not a mechanic so I need a bit help on my future weekend work.
Forks are Marzocchi. I guess  Marzocchi: 38mm (1000>80, 1200). I have 95 kg and lot of times my girlfriend is on bike to.

I found this:
http://www.laverdamania.net/suspensiongb.htm

and this topic
http://www.laverdaforum.com/forum/index.php/topic,89336.msg267326.html#msg267326

As I read some put 7,5W oil, some else put 10w , 15W ... What you recomend for normal driving?
Someone recomend 300cc , this means 0,3 litre of oil?

Than, what about measuring in mm.
As I understand I have to completly drain the old oil out of fork, than put new oil inside and measure for the top of fork to level of oil? Upside down. 
How much mm? ...

Thanks in advance
 
Done it twice last week.Didn't like the 15wt.BTW I have Cerianis,similar but maybe the damping holes might be different so don't take my oil as gosble.First you need to undo the bolts or screws down near the bottom of the fork,on the side.There pretty small.You then pump the forks to force the old oil out.Handily to have someone with a bucket on each side,its messy.Wash the oil off the tyre and brake dam quick.Put th bolts back in.Put the bike on the centre stand and undo the fork caps,take care as the spring is under a bit of pressure.Pull whatever is in the fork including the spring,take care to keep it in order.If the forks haven't been stripped for a while consider tipping in some Kero and lifting the wheel up and down to slosh out any crap.Pull the drain bolts and pump out the kero and crap.Drain bolts back in.Add maybe 200 cc of oil,I am now at 10wt, again pull the wheel up and down to flood the internals of the fork.I cable tie the brake on to stop it spinning while pumping it.I then use a car jack to jack the wheel all the way up.Take care not to have it fall off the stand.With the wheel all the way up I then set the level using a Turkey Baster,thats a rubber bulb like gadget that sucks up fluid.I use a bit of hose cut to the desired height.130mm.Again pump the fork to completely flood the forks and bleed out any bubbles.Jack it up and check the level.Drop the forks down and reassemble,be very careful putting the caps back on,very easy to strip the thread.Thats about it.
 
If there was a need to flush out with kero I'd be more incline to drop the fork legs off and strip the forks for a proper clean. Only 1 M8 cap screw and a 1 circlip and it all comes apart.
 
fork oil weight relates to personal choice, and ranges from people using 5 weight to people using 30 weight, and all swearing their choice is the best...

clean fork oil is better than dirty fork oil.

Vince describes changing the fork oil with the forks intact. There is a drain plug/screw on  each fork leg, not far above the front axle, that will allow you to drain most of the dirty fork oil. Pumping the forks up and down as Vince describes will get most of the dirty fork oil out. Then put the plugs back in.

To add fork oil back in, you will have to remove the fork tops. If you still have the so called Jota bars on your Mirage, the handlebars will block you removing the fork tops. So, the handle bars will have to come off, then remove the fork tops with the appropriate tools. Once the fork tops are off the forks will collapse as the internal springs will no longer hold them up.

Fill each fork leg. Impossible to give you an amount, as no way of knowing how much dirty fork oil is left in the fork legs. Start with maybe 1/4 liter, then with the fork legs collapsed, measure the "air gap" from the top of the collapsed fork leg to the fork oil surface, and adjust as desired with more or less oil.

The remaining issue with this method is all the dirty crap that will remain in the bottom of the fork legs to continue to act as grinding past going forward.

The more preferable way to do this is to strip the forks. Best to have an air impact gun available. Remove the front axle and wheel. The one allan head 8 mm bolt you need to remove is in the middle of the inside bottom of the fork leg, only accessible after the axle is removed. The allan head bolt is threaded into a damping rod that is not fixed in position and can rotate, so leave the top fork cap on to maintain spring pressure on the damping rod to try and prevent I from spinning. Then spin the allan bolt out, and the fork leg bottom will slide right off the fork tubes, allowing you to clean it out thoroughly. If you don't have the necessary tools, consider getting someone to help you. You will be amazed at how much fine silty crap will be in the bottom of the fork legs. You will be amazed at how easy this process is to do with air tools, especially removing the 8 mm bolt, and how hard it can be trying to do it with an allan key with the sucker spinning uselessly, frustrating the heck out of you.

The level of difficulty to strip the fork legs is relatively low as long as you have the correct tools available.

If you do strip the lower fork legs and are starting with dry internals, then it will take a bit more than a third of a liter in each fork leg. Buying a one liter container of, say, 10 Weight, will do both fork legs with some left over.

Paul LeClair

 
Lots of additional good points,my forks have been apart many times in the 25 years I have owned the bike so I know there clean inside as the first time they did come fully down.BTW if you do fully strip them its a no brainer to fit Cartridge Emulators,not that expensive and well worth the effort.I do it my way as pulling the 3C front guard is not my favourite job once fitted with the grommets and spacers.
 
thanks guys for nice instructions, I will see what will I do. I think to buy 15w oil for now. If I will have time, i will unmount forks down and do a proper job.

Thanks

 
When I cleaned my '78 Jota forks the first time, even stripping them there was still a lot of black gunk at the bottom of the sliders that gentle rinsing with solvent wouldn't remove. My local cheap Chinese tools emporium had an engine washing wand for use with an air compressor, it siphons in your solvent of choice. I spent a few minutes blasting up and down and noticed the walls of the slider were also getting cleaner as ground-in crud got blasted out. Hadn't expected to see that. So I washed a few times with clean solvent, then finished off with an electric pressure washer and detergent. I don't think the sliders were ever as clean, even when they left the factory!
Mind you there was also significant wear visible. Fred Howie once tried to talk me into fitting Teflon bushings on my old triple with the floppy 35mm forks but I bought new sliders 'cos they were cheaper, I think about $35 each at the time.

Ken
 
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