Suspension Setup

[trapezeartist]

I don't think I've touched the suspension setup on my 2014 250 Evo since I got it last year. But now being under house arrest, I've cleaned and polished everything, I stood beside the bike with rag in hand defying any speck of dust to land on it, and then I thought I would see if I can do anything to improve the suspension generally. I've just been looking at the Owner's Manual and that is about as much use as a chocolate teapot.

My intention is to set up the sag by adjusting preload at both ends. I've seen figures of 33% and 38%. Any other opinions?

I think it's best to get the oil out of the forks and replace it as I have no idea what is in there or how much. What weight of oil do people recommend? How do you measure the correct amount? Do I have to drop the stanchions out of the triple clamp and work on them separately?

Finally I will have to adjust the damper screws. What settings do people suggest? I weigh about 80kg.

Thanks.

Edited March 28, 2020 by trapezeartist

[totty79]

I followed a guide for sag which is no longer online so I can't help with that.

Oil measurement differs by year, could be height or grams, but go with the manual.

I guess you could keep both forks in the bottom yolk but removing them separately would be easier.

Ignore the marketed oil weight, the cst value is more meaningful, match it to the oil in the manual, the weight may turn out to be 2.5w or 5w. If you get it wrong you'll run out of adjustment.

Adjustment, see how max and min feels to understand the effect, set to middle and tweak as needed.

[lineaway]

 Setting sag on a trials bike never truly works. We hear it a lot with all the Enduro guys buying trials bikes now. Tightening up the suspension is counter productive as this creates a stiff ride that bounces off obstacles and the bike does not get traction like it did. But you must have the correct springs for your weight. Running soft suspension is not the same thing as the springs sacked out with too much weight.

 If you are going to the trouble of changing the oil you might as well do it right. Take them off the bike and flush them clean, then refill to the proper height. Which is in the owners manual.

[trapezeartist]

And it was all going so well....

I dropped out the stanchions and drained the oil out of them. Both were low on oil: the right hand was 125mm below the top when it should be 65mm. The left hand should be 125mm but it was way less and I couldn't measure it. So I refilled with Putoline HPX 5W and carefully set the oil height to the spec.

There were a couple of issues but I decided to park them for another day. I couldn't get the plastic tube out of the left leg (as mentioned in the other post on here https://www.trialscentral.com/forums/topic/70417-beta-evo-left-fork-spring-stuckurgent/) but I thought I could just leave it. The preload adjuster is thoroughly seized in the cap so I will have to get a new cap and adjuster when the house arrest is over. Meanwhile there appeared to be only a tiny amount of preload, so no worries.

Once it was all back together I started checking sag. I was working on my own so my measurements weren't millimetre accurate but they were good enough. I was only getting 31mm of sag which equates to 19%. Bouncing down on the front showed that it was very stiff. For comparison the rear sag measured over 100mm. The manual doesn't give a figure for rear suspension travel but I'm pretty sure it's not 300mm so it appears pretty soggy, though it seems OK subjectively.

So why has the front become so stiff? Possibly there's a much stiffer spring in there, and the previous owner compensated by lowering the oil level to reduce the effect of the "air spring". I tried cracking open the caps so that the air leaked out on bump. It didn't make much difference. I'm puzzled, so now trying to borrow a slide hammer so that I can get the spring out and hopefully identify if it's a standard or fat-boy spec. I could lower the oil levels and see what that does, but it seems all wrong to try to make two wrongs = one right.

Final comment: pushing down on the middle of the bike shows an extreme difference between the deflection of front and rear.

 

[thall1]

When I spoke to beta UK for 2013 & 2014 4t fork air gaps they suggested 60mm rh and 120 Lh.

on the right fork did you gently pump the cartridge to expel all the air from inside it?... also I do the rh  first and leave it with the cap off while I do the left.. that way the all the smaller air bubbles generated after pumping the cartridge have a chance to float out. 

[huski]

Are you saying 100 mm of rear static sag or with you on it?Think the rear travel is around 180/200 mm so it's too soft.When I had an Evo I had to get a heavier spring,the standard one was way soft for my (heavy) 85 kg,don't know your weight.I found it balanced the bike out really well

[trapezeartist]

Thanks for your comments thall1 and huski. Both valid points, I think. However I was thinking about it in bed this morning and I believe I made a silly error. The air gaps are supposed to be set with the fork on full bump. I forgot that and then because I couldn't get the spring out I filled the left hand leg on full droop.? So next time out in the garage I'll be trying harder to get the spring out and then hopefully refill to the correct level. I have some urgent grandfatherly duties over the next few days though, so it may be later in the week before I can do it.

[huski]

It's definitely going to be over hard with that amount of oil in.Think the correct oil quantity will sort it

[trapezeartist]

I corrected the oil level in the LH leg and it feels much better. Sag is still measuring 29% though which would seem to be a bit stiff.

By way of contrast I found that the preload on the rear was not to spec. I wound on an extra 2mm to get to the baseline and 1.5 turns more for my weight. The sag is still not far short of 100mm so it looks like I need a stiffer spring. I only weigh 75kg so maybe 80kg dressed to ride.