Suspension tuning advice
 

Been trying to get the suspension on the '11 GasGas EC250 dialed in for several months now and can't seem to get it where I want it. It's pretty good but I know it can be better. I'm hoping for a little advice to get me going in the correct direction.

I'm right at 140lbs without gear and a mid to bottom B rider/racer. I ride rocks, hard pack, sand, and silt, from hike-a-bike technical to hare scrambles/GP's, and some very beat up trails.

Forks are Marzocchi PFP 48's, .38kg main springs, 1.4 cartridge spring, Maxima 85/150 5wt oil, 210cc cartridge, 300cc outer, 0mm main spring preload, PFP fully out, compression 19, rebound fully closed, 5mm above clamps. Shock is Ohlins 888, 4.8kg spring, sag 103mm, hsc 3, low compression 26, rebound 8. IIRC, suspension front and rear was re-valved by Motolab for AZRickD who is a 180lb rider of similar skill and when I bought the bike it had .44/5.4kg springs installed

Front is really plush eating up trail junk, does well on square edges, and zero deflection. However, the front wants to wash pretty easily and when riding sand it is really tough getting the bike to go where I want to and to hold a line. Tried slowing the rebound as much as I could without fixing the problem. Next I started dialing out the PFP in hopes of slowing it down. It seems to have helped some but it still feels like I'm maybe 3-4 rebound clicks away from being where I want it.

The rear kicks a lot but not severe as if it's going to eject me but it definitely feels busy.

So, my left fork seal started leaking so I gotta have them out anyway. Should I try to switch to a heavier fork oil, 26.7cst@40 vs my current 16.2cst? Maybe raise the forks some more? Trying to avoid a re-valve right now as my budget is tight being it's the holiday season. I just don't know which way to go as my mind is reeling from all the variables and I think I have lost sight on how to get it where I want it.

Are you happy/competent to pull the damper shaft out of the cartridge when you're replacing the seal? And do you have the time to consider measuring the current rebound stack, comparing to stock and discussing adding some more rebound to the bike?

Yes, I can pull the rebound. Haven't done it before but I haven't ever found anything mechanical I couldn't do. I figured It was going to need to have the rebound stack modified. The next race isn't until January and I have my old KDX to ride until then.

That's what I would be doing.. and mechanically it's pretty straight forward.

Take a look at this thread
http://www.gasgasrider.org/forum/sho...=11075&page=30
In posts 292 onwards Jacobi and myself discuss the rebound stack modification that I did a couple of years ago

For riding in sand you probably went in the wrong direction. Let the rebound as it was and start to add more damping, and if possible more pre-load, then make sure your forks are flush with the clamps, if not push them in. What you want is a light front that doesnt dig into the sand.
The deeper the sand the more you need to increase your corner entry speed and steer with the rear keeping the front light.

Ok, tore the front end down. Drained both forks and disassembled the leaking leg. Bushings look good. Even the seals look good (inspected using a magnifying glass) but there was a lot of dirt in them. As typical for these forks the oil was filthy with just about 45 hours on it.

Trying to figure out how to get the rebound rod/stack out. Do I have to remove the clicker end? Also, do I just unscrew the nut around the rod going in to the aluminum tube (section w/the preload adjuster)? What about the cartridge section from the tube?

Yeah, I've read that thread completely through at least three times now and constantly reference it. :D

My issue is that with our rides/races it is never just sand or hard pack/rocks. It's always a mixture to some degree and the rocks are brutal out here sometimes so I need it to be very compliant to keep from being beat to death. I figure I can use the PFP to help find a good balance once my valving is sorted.

Yeah the collar/locknut on the damper rod that locks down onto the base plug while back right off the shaft. You may need to make up a little holder to crack it loose without damaging the shaft.. it won't be really tight though.

Then with the comp adjuster assembly (top of the cartridge) removed the whole piston and shaft will lift out the top.

Take note of the piston band. It's stepped and comes off the mid valve.

On re-assembly an o ring will hold the piston band in place and pop off when you push the piston back into the cart.

BE VERY CAREFUL with the threads on the damper rod passing through the cart seals. Some people tape them, others take the edge off them a little.. they can cut the seal if you're too forceful.

Going back together is opposite, but you will need to index the base plug and locknut to set the number of clicks on the rebound needle. It's not too hard.

Another option is filling the threads with grease as suggested by Paul Thede in the Motorcycle suspension bible. I have done so with good results (no leaks afterwards).

Yeah I usually make sure they're lubricated as well.. however I don't think packing helps that much.. It's the edge that can be sharp... and the OD on the thread is usually a touch smaller than the OD on the shaft.. It's more of a concern if you reem it through without it being straight.