Monster Marzocchi Fork Internals - Ducati.ms - The Ultimate Ducati Forum
 
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post #1 of 8 (permalink) Old Jun 17th, 2019, 10:13 am Thread Starter
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Monster Marzocchi Fork Internals

Hi all,

I just picked up a 2008 M695. It had about 7500 miles, but I don't know its complete history. Therefore and because its fun, I'm going through the whole machine, checking, cleaning, and replacing things. One of the jobs I'm doing is the forks (seals and fork oil).

It has non adjustable, 43mm forks. I believe they are Marzocchi according to what I've read. I pulled them off, checked the guts, cleaned them up, and replaced the oil and dust seals. I was putting new fork oil in them (Belray 5wt, which may be a bit light, but its what I had on-hand) and was working the damper rod to bleed the air out. On the right fork, as I bled the cartridge, I was able to feel normal damping resistance as I bled it and added fluid. However on the left cartridge, following the same process, I never felt any significant damping resistance. In fact, I did it twice but never got any significant damping resistance.

Any ideas why? Any chance these could be the types with rebound in one side and compression on the other? There was some compression resistance on the left side at the bottom of the stroke (which the right side didn't have). But it seems to me the left cartridge may be bad.

Any help or experience would be appreciated.

Regards,

Tom C.

Ducati: 2013 848 Evo, 2000 ST2, 2008 Monster 695
Non-Ducati: 2009 R6 (Track Bike), 2008 KTM 250XC (Practice Bike)
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post #2 of 8 (permalink) Old Jun 17th, 2019, 10:49 am
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Originally Posted by ih574 View Post
... Any chance these could be the types with rebound in one side and compression on the other? There was some compression resistance on the left side at the bottom of the stroke (which the right side didn't have). But it seems to me the left cartridge may be bad....
This was my very first thought. However, full disclosure here ... I don't know what I'm talking about. I just purchased my very first Ducati about two weeks ago.

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post #3 of 8 (permalink) Old Jun 17th, 2019, 5:30 pm
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Not an expert on those but to my knowledge both legs should resist movement. You said you ď checked the gutsĒ, does that mean the cartridges were removable ? I ask because the Marzocchi forks I had did not have removable cartridges so all I could do was clean them and replace seals, springs, and fluid. Both sides had resistance. If they donít come apart, and you find that both legs are supposed to have resistance, you could put heavier fluid in the one with weak resistance.

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post #4 of 8 (permalink) Old Jun 17th, 2019, 6:44 pm
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ime, with marzocchi 2005 ish and later one side is rebound, the other comp. same as the sc/gt1000.

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post #5 of 8 (permalink) Old Jun 17th, 2019, 7:26 pm
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Thatís a plus, as you can use a different weight in each side to improve control. Now would be a good time to set your sag. Even with stock springs you should be able to get it close.

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post #6 of 8 (permalink) Old Jun 17th, 2019, 10:55 pm Thread Starter
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Thanks all. I saw some posts on some other sites that confirm that this era Marzocchis for this application use one rebound leg and another compression. I ordered some heavier oil to experiment, so I'll change out the oil and see what happens. I will probably adjust the air gap as well. The on-line manual I found states 104mm. However, I found a 50mm gap when I first opened them up. So I'll experiment with that a bit.

The cartridges are removable. I was able to remove and reinstall the cartridge in the right side rebound side. However, the bolt was too tight on the left and I didn't want to force it. And anyway, there was nothing I could do with the cartridge anyway, so I left that one in.

The manual states the air gap should be the same for both. However, from some other details about the fork rebuild in teh manual, it seems to refer to symmetric fork legs. The parts seem a bit differnet and it references a compression adjuster in the bottom (where these forks only have bolts.

I'm not sure how to set the sag other than change the springs (from the current dual rate springs) or change the preload spacer.

I was able to measure the fork bushings so I could pick up some spares based on measurements since I can't find them advertised for these forks. The current bushings are in good shape, but still wanted to source some replacements just in case.

Thanks again for your thoughts and recommendations.

r-

Tom C.

Ducati: 2013 848 Evo, 2000 ST2, 2008 Monster 695
Non-Ducati: 2009 R6 (Track Bike), 2008 KTM 250XC (Practice Bike)
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post #7 of 8 (permalink) Old Jun 18th, 2019, 6:59 am
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Exactly, you either buy springs for your weight or you adjust the length of the spacers to get the proper amount of sag.

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post #8 of 8 (permalink) Old Jun 18th, 2019, 8:10 am
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if everything above the oil level is the same, then the oil height should be the same both sides.

the only thing the oil height affects is the air spring. was it 50mm with the springs in? 104mm with springs out would be std (sounds about right), which gives quite a lot of increase in rate in the last 1/3 of travel. if you increase the spring rate to something in the 0.85 - 0.95 range i would drop the oil to 140mm or so. std springs are very soft for the first 70 - 80mm of compression, but depends how much you weigh too.

playing with these forks here:

https://bradthebikeboy.blogspot.com/...nd-impact.html
https://bradthebikeboy.blogspot.com/...nd-impact.html

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