Update and More WR450F Questions/Issues on Suspension and Engine


4 replies to this topic
  • Magnetic

Posted July 30, 2011 - 02:46 PM

#1

Well today was my first time out since all the "upgrades" I installed. To recap:

Guts Racing tall soft seat foam and comp. cover
FC .50 fork springs
New fork seals and dust covers
13T JT front sprocket
FC 6.0 shock spring
YZ style rear fender
New spark plug
New fuel line
Greased linkage needle bearings
Serviced air filter
Rox 2" Riser
Lowered the pegs

Forks: Compression all the way out, rebound out 7, oil 150mm (min)
Shock: Compression 13 out, HS 1.5 turns in, rebound 13 out
Sag: 105mm race, 25mm static
Tires: 15 psi
Prior to this, everything was at factory settings and had 140mm sag.
Me: 6'4" and 250 without gear.

Today's terrain: Damp loamy sandy conditions compared to dry dirt and sand previously.

Impressions:
My bike went from slow turning and planted to quick turning and kinda twitchy. It allowed me to get out of a few hairy spots on the trail, but almost dumped me off the bike a few times too though. The steering is almost too responsive and the back end goes everywhere. The front end tended to dig and dive in the sand unlike before. Even with the compression turned all the way out, it still never bottomed one time. The few 3' jumps I hit landed nice and smooth. Other times the last 25-33% is kinda harsh. It does sit nice and high, which I like. The front was stiffer, as was expected with the springs, but bordering harsh. The seat spanked me a few times crossing logs, so maybe I need to dial in more rebound and a little less compression.

The Guts soft seat was awesome at first, but maybe a tad too soft after 3-4 hours of riding, but not enough to switch it to medium.

Rox/Lowered Pegs are cake! I was able to stand so much better and comfortable. I stood more than triple the time as my last outing.

I was thinking with the 13t front sprocket I would be able to lug it more in 3rd gear. Dropping a tooth in the front didn't change this at all. Also, while I was trying to lug it at low rpms I occasionally heard/felt what might have been detonation.


Question #1:
What do you think most contributed to the twitchy/fast handling? I want to dial about half of it out I think... or maybe I should get used to it and learn to control it? I'm also thinking about putting one of the stock springs in with a .50 to soften it back up a little without lowering the ride height too much. Any other input/suggestions from other big guys?


Question #2:
Too much low rpm load = detonation? I had put some fresh premium fuel in the tank, but maybe I was XR'ing it too much? It sounded almost like a metallic clank and could be felt all through the bike.

Thanks for taking the time to read and respond. I love this thing, and I'm having a ball dialing it in!

Magnetic

  • Krannie McKranface

Posted July 30, 2011 - 03:43 PM

#2

[quote name='

Question #1:
What do you think most contributed to the twitchy/fast handling? I want to dial about half of it out I think... or maybe I should get used to it and learn to control it? I'm also thinking about putting one of the stock springs in with a .50 to soften it back up a little without lowering the ride height too much. Any other input/suggestions from other big guys?



Question #2:
Too much low rpm load = detonation? I had put some fresh premium fuel in the tank, but maybe I was XR'ing it too much? It sounded almost like a metallic clank and could be felt all through the bike.

Thanks for taking the time to read and respond. I love this thing, and I'm having a ball dialing it in!

Magnetic[/QUOTE']

#1 Don't change a thing for at least one more ride. Once you get used the the rear end bouncing around, you will realize it will never goes wild, just out a bit. Re-valving would help immensely. Start your corners earlier, and straighten the apex. Now that it turns you no longer have to turn the old way, you can pick your line, and change it as you go.

#2 Might be chain slap, might be piston slap. If it's detonation, you would surely hear it react to load.

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  • Magnetic

Posted July 30, 2011 - 04:10 PM

#3

#1 Don't change a thing for at least one more ride. Once you get used the the rear end bouncing around, you will realize it will never goes wild, just out a bit. Re-valving would help immensely. Start your corners earlier, and straighten the apex. Now that it turns you no longer have to turn the old way, you can pick your line, and change it as you go.

#2 Might be chain slap, might be piston slap. If it's detonation, you would surely hear it react to load.


By the end of the ride I was getting more used to it. Any idea which change caused this? I'm guessing it was the sag, but I don't know.

I'm pretty sure it was detonation. It sounded like a clank/rattle from the engine. I will try some AV Gas the next time out and see if that helps. Should I be able to lug this engine down to idle speeds, or am I asking too much of the engine?

  • Krannie McKranface

Posted July 30, 2011 - 04:52 PM

#4

By the end of the ride I was getting more used to it. Any idea which change caused this? I'm guessing it was the sag, but I don't know.

IMHO

I'm pretty sure it was detonation. It sounded like a clank/rattle from the engine. I will try some AV Gas the next time out and see if that helps. Should I be able to lug this engine down to idle speeds, or am I asking too much of the engine?


Correcting the large sag made the bike oversteer more. This is good. But you have to get used to it. It will 'buck' much more now, if the suspension is off. More than with 140mm sag.

By the sounds of it, you have your suspension set up way to soft. If the bike 'hobby horses' at all, it's too soft.
It helps to go over the same piece of ground over and over, doing clicker changes, until the bike is razor sharp in corners. Then back off the rebound to see if you can get it comfortable too. If not, then back off the compression, and put the rebound back where it was.

How the bike responds to hard throttle and wheel stands also tells you a lot about rear damping. If I can;t easily lift the front wheel in just about any circumstance, the rear compression damping is too soft.

I too have .50/6.0 on my '07 (second one, just restored it), with ESP rear and ASR front re-valving.
Not sure about the rear yet. Seems a bit under damped. The front is much better than stock, and is better (for fast single track) than the SP work done on previous WR's. I emphasize single track, as that is the only type of riding this new '07 has done. I ride a local Mini-cycle track with all tight second/third gear corners, and it has never been graded or maintained, so it is consistently inconsistent in surface type. Great for testing stuff out. The straights are mostly gopher hole mounds, so I can do two laps and know conclusively if my suspension tuning is going in the right direction.




AV gas has lead in it, which will mask detonation issues due to leaness. It also is not high-stress oriented (constant rpm). So don't use too much too often.

  • Magnetic

Posted August 01, 2011 - 11:59 AM

#5

#2 Might be chain slap, might be piston slap. If it's detonation, you would surely hear it react to load.


I was feeling this right off of idle in third gear, but I wasn't heavy on the throttle. After more reading I am now revising my opinion, and I think it was chain slap. I'll double check my chain adjustment. I did change the front sprocket and I don't remember hearing it before doing that....




 
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