fork oil

Depends on the bike. Ceriani triples, 270ml recommended, but if you have new springs that gives a bit too much bounce. With old sagged springs you probably should try 270 then drop the level by a measured amount, say 1cm, at a time, keeping the level the same in both legs. Use a syringe (chemist shop) with a long tube to draw up the oil in a controlled fashion, and a cork on the end of a stiff wire to measure the level in the stanchion. You can also buy tools made to do the job (Motion Pro and others) but if you're only doing it once the home-made stuff is plenty good enough.

Ken
 
bevelman said:
250 ml of 15 weight the go?
Click to expand...

Bevelman,
On my '81 Jota I'm running 300cc of a 50/50 mix of 5 and 10w. The added oil helps with anti dive characteristics, and I prefer a slightly "softer" oil mix to help make the suspension a bit more supple. Handles mid corner bumps better. 300cc is approximate, I go for a 6 inch (152mm) air gap on top.
 
bevelman said:
250 ml of 15 weight the go?
Click to expand...

Definitely, on the other hand if it's a Chott, perhaps not. Then again if it's an Alpino you might want to rethink the quantity. Mind you, if it's a 125cc Lesmo you could be a mile out, same if its 100cc Lusso. Of course it could be a Ceriani equipped SF in which case I'd consult the manual. Or are we talking about one of the Zane models here?
 
I think the clue to which bike he is asking about is his avatar and signature, Paul is asking about his 81 Jota

 
An 81 Jota would have 38mm Marzocchis

Page 13 of the Marzocchi Fork Manual says 400ml for 38mm forks (260ml for 35mm forks).

Doesn't mention viscosity though. I use 5 weight oil with gold valve emulators and running the original springs - gives a nice plush ride with good damping. I have some lighter progressive springs that I mght try some time. I may find the damping will need to be a bit stiffer with the light springs.

With the standard Marzocchi ball-valve damper, I'd advise not to go above 10 weight.

Cheers,
Cam
 
Hi Rob

It all depends on rebound damping. The bloke I bought the gold valves from (Steve Wood - Suspension Improvements) said the rebound damping on the (asian copy) valves was a bit stiff. So I'm using lighter oil to get the rebound damping right, then the compression damping can be adjusted by tweaking the pre-load on the wee springs on the damper valves. The heavy fork springs tend to give the forks a stiffer feel too. The front end actually feels quite good and flows over the road bumps nicely, without trying to throw me off the bike like it used to.

Cheers,
Cam
 
Dellortoman said:
An 81 Jota would have 38mm Marzocchis

Page 13 of the Marzocchi Fork Manual says 400ml for 38mm forks (260ml for 35mm forks).

Doesn't mention viscosity though. I use 5 weight oil with gold valve emulators and running the original springs - gives a nice plush ride with good damping. I have some lighter progressive springs that I mght try some time. I may find the damping will need to be a bit stiffer with the light springs.

With the standard Marzocchi ball-valve damper, I'd advise not to go above 10 weight.

Cheers,
Cam
Click to expand...

Hi Cam

for 38 mm Marzocchi's on an 81 Laverda, it would have to be 300 cc/ml, from a fresh fork strip and rebuild, forks completely dry.

400 cc/ml would probably overflow out the top of the fork leg when you dropped the fork spring in.

sometimes I do what Ed does and go half 10 W and half 5 w, sometimes I am actually able to buy 7.5 w, and other times I just use 10W for a completely stock set of Marzocchi's on a fresh stock fork rebuild.

I just rebuilt a set of 38 mm Marzocchi's the other day from an 81 1200, I used 300 cc/ml of 10W in each fork leg from dry, typicaly gives a nice firm but plush ride and decent handling.

Paul LeClair
 
I recently replaced the seals in my 38mm Marzocchis and I refilled them with 400ml of #5 fork oil (as per the manual). There was still plenty of air gap and the forks work fine.
But I take your point, all you need is enough oil to immerse the damper valve. Any more than that does nothing for damping. It just makes forks stiffer because the air gap is smaller. I have tried running with less oil in my Ducati (same forks) but it doesn't seem to make much difference.

Cheers,
Cam
 
Cam's advice that the min fork oil qty is that which covers the damper valve is (of course) right and correct, but if you are seeking to minimise your 'air spring' rate, don't take this too literally and suck out every last cc. There should be a small amount of oil over, as, in use, an amount of oil gets hung up in the surfaces of the stanchions/springs/spacers, etc. Hag
 
quantity of fork oil to use is interesting. I just checked my RGS Laverda factory manual. As you know, the RGS forks are longer than the earlier forks. Laverda RGS manual specifies 300 cc/ml..........

Paul LeClair
 
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