2018 Chassis Set Up Tips - Planted Front End

ssaulnier

Silver Level Site Supporter
I took my new 2018 300EC out for a ride this weekend on tacky dirt, mud and sand. Bike worked great but I could feel the front end pushing toward the outside of the turns and trying to plow straight ahead a little more than I like. Sliding forward on the seat helped plant the front tire a little, but not enough.

She now has 3 hours on her, so still early days. Still looks like new... very sexy beast. I see lust in the hearts of the KTM/Honda/Yamaha riders!

Stock jets 42 pj, 172 MJ with replacement Suzuki NEDH needle Top clip running very smoothly at 50 to 70 degrees F until the power valve opens and then she rockets off a bit too hard whilst in the trees and makes my butt pucker. Have not checked the power valve setting yet but might tame her a bit before I eat some tree bark.

Please advise your thoughts on best ways to increase front wheel traction from list below or add your own thoughts. I weight about 220 lbs suited up for riding.

Ideas to Improve Front Tire Cornering Traction.

1. Rear static sag was 45 mm as delivered (rider sag 112 mm in street clothes 200 lbs). I increased the spring preload as much as I could with my hands, but it wasn't even a full turn. Static sag with added preload is now 35 mm (manual spec is 35 +/- 5 mm) and rider sag with full gear is 120 mm (spec is 100 +/- 5 mm). So the rear end is riding too low and taking weight off the front wheel.

2. Presently running stock Metzler 6 days FIM front tire at 8 psi. Reduce pressure or replace with Bridgestone M59 or Shinko MX216 90/90x21?

3. Set forks to comfort settings recommended in manual for compression at 18 click out. But may not have turned the rebound out that far to match. Need to check.

4. Front forks height in the triple clamps are unchanged. I have not changed them and don't recall where they are. Perhaps raising the fork tubes in the clamps will put more weight on the front end, but also make it harder to adjust the fork top compression clickers. Think I should reduce the rear sag first.

Thanks for your advice.

Cheers, Steve
 
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My 18 xc300 forks are a completely different animal at 12 hours than they were at 3 hours. I'm a big dude and mine took quite a bit to bed in. Up until hour 6 I was 2 clicks out on compression from the manual's "comfort" setting and the forks were harsh enough on small hits. I also experienced more of the symptoms you are describing.

After 6hrs I felt them getting softer and by 10hrs I found my clickers in the "standard" setting.

Other than wanting to revalve the shock on the rebound side I'm pretty content with the feel of the suspension now. Hopefully your issues bed in too.
 
You're on the right path.. All good points. I'd double check your sag figures. Get the rear riding a bit higher maybe.. or drop the forks a touch more.

Sometimes too little rebound damping will stand a bike up in a corner and push it to the outside, but that is more of a case where it tips in and then unsettles..

dzhitshard. With the shock, do you find HSR a bit too quick?
 
Thanks guys I?ll tweak a bit and ride some more and let you know how I get on! It?s good to hear I am on the right track. Just need to make more time for riding now that the weather has turned here in South Texas and it?s not beastly hot and dry anymore. The cool temps and damp dirt are a welcome change.

Cheers, Steve
 
1. Rear static and rider sag was about 5 to 10 mm too much per manual (don't have my notes with me). I increased the spring preload as much as I could with my hands, but it wasn't even a full turn in so I likely need more preload. I suspect the rear end is riding too low and taking weight off the front wheel.

I agree 100% that the forks need about 10 to 15 hours until they are consistent. It was the same on my 300.

When you say the sag was too much, are you talking about static or dynamic sag? While you can correct the static sag with more preload you cannot correct the dynamic sag by adding more preload. Only changing the spring for a firmer one will solve a too low tail. One of the biggest misunderstandings in motorcycle history btw.

If the tail hangs low when riding you just need a firmer spring. Many riders prefer a slightly low tail as it helps in the very fast sections, especially on sand or tacky mud.

The running wide effect can have different reasons, so you wont get around of playing with clickers, tyre pressures and bar psoitions.

Let us know how things are going ;)

Cheers Doc
 
I agree 100% that the forks need about 10 to 15 hours until they are consistent. It was the same on my 300.

When you say the sag was too much, are you talking about static or dynamic sag? While you can correct the static sag with more preload you cannot correct the dynamic sag by adding more preload. Only changing the spring for a firmer one will solve a too low tail. One of the biggest misunderstandings in motorcycle history btw.

If the tail hangs low when riding you just need a firmer spring. Many riders prefer a slightly low tail as it helps in the very fast sections, especially on sand or tacky mud.

The running wide effect can have different reasons, so you wont get around of playing with clickers, tyre pressures and bar psoitions.

Let us know how things are going ;)

Cheers Doc
So winding on more compression(preload) does nothing for rider sag?
 
My static sag was too much. It should be between 30 mm to 40 mm per the manual, but mine was delivered at 45 mm. That means there is not enough preload, or stored energy, on the spring. I didn?t have much time to wrestle with the spring so I loosened the lock washers and added as much preload as I could by hand. Turns out that was less then one full turn. I could not get my hands on the spring collar to turn it very well and didn?t have time to mess with it and was not really in the mood to bugger it up with a screwdriver and hammer. I did not remeasure afterwards but suspect I need to add a bit more. In addition I should most likely go to the next higher strength spring due to my riding weight of about 220 lbs (100kg) being above the 75-85 kg target rider weight for the 52N/m stock spring. Turns out that the additional preload reduced the static sag to 35 mm which is right in the middle of the acceptable range per the manual.

The idea is to add enough tension in the spring to hold up the weight of the bike without the rider so that it only sags about 35mm +/- 5. That allows the spring to react properly to bumps, push the rear tire down into the dirt properly on the backside of bumps or launching off fallen trees, etc. Too much preload on the spring means that it takes a bigger hit to move the rear wheel in order to overcome the excessive stored energy in the spring caused by the excessive preload.

But if you weigh more than the target weight like I do then that ideal amount of spring preload will not hold up the rear end of the bike high enough to transfer enough weight to the front wheel for good traction and turning stability.

Having said all that sometimes less preload on the spring and a little higher rear sag is OK for a particular rider, bike, speed and riding conditions, as stated above.

In my particular case, As the others have stated, after 10 hours or so my front forks should break in and will most likely ride a bit lower in the stroke which should transfer more weight onto the front tire, giving it more grip and giving me more confidence. Then I can evaluate if I really want a stronger rear spring.

But I really need to measure the static sag again and bring it up to spec before I go riding again. No sense risking having the front end wash out and eating dirt because I was too lazy to wind in another turn of preload on the Shock spring.
 
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So winding on more compression(preload) does nothing for rider sag?

Basically straight rate spring compresses at say 5.2kg/mm ... so it takes 5.2kgs to compress the spring one mm. Adding preload just increases the amount of weight/force before the spring compresses further.. put a big load of weight onto it and it'll overcome the preload and continue.

Damping also influences where in the stroke the shock rides.

That's why a heavier spring with less preload can feel plusher in the initial action. You don't need to overcome the preload to set it in action. The problem being too heavy is usually when you are hitting something after already being half way through the stroke. The sometimes she gets a bit too firm instead of using the travel up.

This link explains it pretty clearly
https://lifeatlean.com/teach-me-suspension-everything-preload/

PreloadExample.png
 
I put another 2 hours on the 300 today for a total of 5 hours. I am feeling more comfortable on the bike and we are both getting to know each other.

I noticed that by tapping the front brake on turn entrances the front end settled down and turning felt more secure. I was not applying much front brake last week in the mud so the front end wasn't settling due to the new fork seals and components.

Happy Days! I am trusting the front end more now. But do have some doubts about the stock Metzeler 6 days tire. I am not sure I should trust it as much as a Bridgestone M59. Of course the problem could be that I have too much rider sag and need a heavier spring to keep the rear end up and put enough weight on the front wheel.

I measured static sag on spec at 35 mm (range is 30-40 mm per manual) and out of spec geared up rider sag at 120 mm (range is 95-105 mm per manual).

Since the ideal rider for the stock 52N/mm rear shock spring is 75-85 kg and I am 100 kg, I am not surprised at the results.

I guess I should source a 54 or 56 N/mm spring.

One other set up tip is that I added an additional turn of slack to the throttle cable using the adjuster on the throttle housing. I thought that there was enough slack already, but this additional one turn of slack gives me better control over braking bumps and while grabbing the front brake lever so I don't inadvertently open the throttle. After this adjustment I didn't scare myself (yet).

I am thinking I should lock wire the throttle cable to the housings on both ends to keep it from getting snagged on brush.

Thanks for your advice and support. I am a Happy Camper so far. :)
 
So winding on more compression(preload) does nothing for rider sag?

Exactly. As I said before this is one of the biggest misunderstandings in motorcycle history.

But even if I tried I could not better explain it as Jakobi did. It says it all.

I had to learn it the hard way. One of my riding buddies asked me to set up his suspension on his street bike. I checked the rear sag and it was too big. I also checked the rider sag with him, a really fat guy, on the seat.

After I gave the spring 1.5 turns the static sag was perfectly within limits. The rider sag didnt change. So I gave the spring another two turns but the rider sag didnt change. I was puzzled and gave it another turn but nothing changed. After that I went to a suspension guy and told him what I have experienced and he just laughed and explained to me how it really works.

The preload does only adjust the height of the bike. He also said, that it is more important to have a correct rider sag than a correct static sag. Depending on the rider weight a point will be reached where the spring is so firm, that you cannot adjust the correct static sag, but once the heavy rider sits on the bike, the sag will be correct....

@Steve: good to see you get ist sorted. I'd recommend you first install a firmer spring, then test ride ist for some hours. If all is good let the forks alone. If you feel you need to get firmer fork springs, then get them. But do test first with just the new shock spring. Good Luck!

CU
Steve

edit: PS. If you install a firmer rear spring dont forget to adjust the rebound accordingly!
 
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