The search for elusive traction...

crasher813
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crasher813
Edited Date/Time 1/3/2016 6:00pm
So, this is really a question for suspension gurus. I raced at a local track yesterday, first one in over a decade. Was pushing harder than I usually do in practice which revealed that my setup was a little off. The dirt was a soft mix of sand and clay with alot of moisture. Rolling the throttle on just made the tire spin like I was in soup. Couldn't not get bite, just wicked in on all the way up the jumps to gain any kind of speed. It's a 2015 yz250f. They are sprung for 150lbs+ and I'm just shy of that at 146. Running 105mm sag, 5 mm up on the front forks. Short of changing to a lighter spring I'm looking for some suggetions. I was looking at slowing the rebound down to keep the bike squatted but my pop (he's an auto mechanic) had suggested softening the compression so it would squat more. Thoughts?
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mx836
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mx836 1/3/2016 10:05am
1/3/2016 10:05am Edited Date/Time 1/3/2016 10:06am
Try more sag if you want it to squat a little more. Pretty sure the YZF needs a different sag setting than your typical bike due to it's design. Put a 110 rear tire on it. With the power of the YZF and your light weight, it's a no brainer.
deltadestroyer11 1/3/2016 10:49am
1/3/2016 10:49am
Too much sag will make your rear end loose traction. Having your bike squat a little is good, just don't over do it with like say 115mm of sag..that's too much. You want your rear end to be pressing the rear tire downward. I would try a normal amount of sag...102-108 and opened up high speed compression a half a turn or so. Also speed up your rebound a click or two.. Just have to expieriment but those settings should give a little more traction. Also the 110/90/19 rear tire is an excellent idea. That would be my next purchase for any 250f.
pete24
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pete24 1/3/2016 11:01am
1/3/2016 11:01am
is your clutch smoked, and you think its spinnin
Gringoe
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Gringoe 1/3/2016 12:02pm
1/3/2016 12:02pm
pete24 wrote:
is your clutch smoked, and you think its spinnin
No, that makes it spin less, poor man traction control.

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Bruce372
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Bruce372 1/3/2016 12:17pm
1/3/2016 12:17pm
Stick to 105 sag. Turn the rebound out. Check your tire pressure
slipdog
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slipdog 1/3/2016 12:18pm
1/3/2016 12:18pm
Your dad is on the right track with going softer on the compression settings.

The problem is the '15 YZF is not sprung for 150lbs, it's more like 185+lbs stock. You need closer to a 5.2kg shock spring for your weight and stock is 5.7kg. You should also drop the fork springs down to around .44-.45 form the stock .47kg. Until you install correct springs for your weight you will just be fighting the bike no matter what adjustments you make.
Hcallz5
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Hcallz5 1/3/2016 12:33pm
1/3/2016 12:33pm
Try a soft terrain rear tire.

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crasher813
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crasher813 1/3/2016 2:12pm
1/3/2016 2:12pm
slipdog wrote:
Your dad is on the right track with going softer on the compression settings. The problem is the '15 YZF is not sprung for 150lbs, it's...
Your dad is on the right track with going softer on the compression settings.

The problem is the '15 YZF is not sprung for 150lbs, it's more like 185+lbs stock. You need closer to a 5.2kg shock spring for your weight and stock is 5.7kg. You should also drop the fork springs down to around .44-.45 form the stock .47kg. Until you install correct springs for your weight you will just be fighting the bike no matter what adjustments you make.
Thanks for the input. I was kicking around the idea of the 110 tire, but I'm pretty much in an open class. Most of the competition is on 450s or 250 two strokes. Giving up ponies and putting extra stress on the motor is probably not my best route. Just need to get the power to the ground. Guess I just have to pony up a few bucks for springs... but part of the reasons. I didn't buy a 450 was not wanting to explain why I spending 600 bucks on parts for a new bike to my wife....
j368
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j368 1/3/2016 6:00pm
1/3/2016 6:00pm
crasher813 wrote:
Thanks for the input. I was kicking around the idea of the 110 tire, but I'm pretty much in an open class. Most of the competition...
Thanks for the input. I was kicking around the idea of the 110 tire, but I'm pretty much in an open class. Most of the competition is on 450s or 250 two strokes. Giving up ponies and putting extra stress on the motor is probably not my best route. Just need to get the power to the ground. Guess I just have to pony up a few bucks for springs... but part of the reasons. I didn't buy a 450 was not wanting to explain why I spending 600 bucks on parts for a new bike to my wife....
A 110 rear is not going to stress the motor at all, but it will help with better traction with the wider contact patch. You're not giving anything up with power either.

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