How to tune Marzocchi MX Comp coil fork for the Mrs.?
My wife (120 lbs.) has a Kona Kahuna with a 2003 Marzocchi MX Comp fork, coil springs, open bath oil damping, non-ETA. The fork is an aftermarket model, not the OEM one supplied with the bike. It has the stock 105mm travel springs that came with the fork. I believe that "light" springs were never offered for this fork.
Any recommendations for tuning the fork for better small-bump compliance? (She's a fairly casual rider and wants a plusher ride.) The fork has 7W Bel-Ray fork oil and has 130 cc's of oil in each leg (per the chart at the Marzocchi website.)
Also, although this is supposedly a 105mm travel fork, if I put a zip-tie around the leg at the dust seal and compress the fork, the most I can get it to move the zip tie is 60mm. Is this normal?
Did you make sure and purge the old oil out? You should compress and extend the fork while upside-down to purge any extra oil before refilling. Too much oil can cause the fork to hydrolock and you wont get full travel out of it.
Bel Ray 7wt is actually a little heavier than stock Marzocchi Oil (Golden Spectro 125/150 Very Light). For a light rider, you should run a lighter oil. Compare the Cst @ 40* on this chart from Peter Verdone...Marzocchi Oil is 26.40
Last edited by mtnbiker72; 05-25-2009 at 09:44 PM.
Yes, I did purge the forks. I was going to let them drain overnight, but after several strokes, there wasn't anything dripping out so I didn't bother.
That is quite the chart, thanks! I just used the Bel-Ray oil because I had a bottle left over from my old motorcycle. Interesting how there is such variation between manufacturers - for example, Castrol 10W is 15.00 and Motorex 2.5W is 15.10.
Is there any rough rule of thumb on how big a step down to take for the rider weight? Since the Bel-Ray is 29.00 I'm wondering if I should jump down to an oil with a cSt value of 20, 15, or even lower..
Not sure if there is a rule of thumb, but I have used Bel Ray 5wt in a older Marzocchi Z3 for a friend and she probably weighed 130-140 (she would never tell me her exact weight). It has a 17.1 cSt so you might try something in that weight range. It worked good with the stock springs.
"Bikes aren't fast--people are fast. Bikes are overpriced. It's an important distinction."---BikeSnob NYC
I believe you can also run it with only 1 spring, instead of 2.
29 some of the time...
Looks like everyone has you in good hands. My recommendations were light oil and only run 1 coil spring. I did this for a friends GF who weighed in at about 130lb. She was much happier with the ride.
Originally Posted by saturnine
how's this for a thread ressurection?
Originally Posted by logbiter
After posting this we had 2 more kids, moved, and to make a long story short, I am now finally getting around to this and have one more question...
Originally Posted by AL29er
Which coil spring to take out, the one on the damper side, or the non-damper side?