Possible bent forks.

NinjaBraap · February 7th, 2017, 02:21 PM

Recently test rode a 2007 Ninja 250 after replacing the ignition switch. Right off the bat noticed that when turning the handlebars it tended to continue in the direction being turned and required pushing on the handlebar to keep from turning all the way into the direction being turned. Since it wasn't my bike, and it had been sitting for about 6 months since it'd been ran last, I had no idea what it'd been like before, nor did the owner. Just from experience though I knew it wasn't right from riding every other bike ever, and from owning a 2004 Ninja 250 and 2008 Ninja 250 of my own.

I immediately suspected bent forks, as the fork bearings weren't stiff and were working properly, and no other parts appeared to be damaged or bent in any way. Visually though the forks looked straight, there wasn't any leaking seals and the wear was even on the pads, so there wasn't any other indications that they were bent. The bike had been down from the previous owner (the bike's current owner is a new rider, and bought it last year), and someone had tried to steal the bike while it sat this winter, and kicked the bike over when they failed to unlock the ignition (why I was replacing the ignition switch).

Long story short figured I'd get a second opinion. Any Ideas or thoughts are welcome, thanks everyone!

Flying · February 7th, 2017, 02:30 PM

Maybe the forks are misaligned instead? Check the height from the top of the fork tubes to the triple clamp.

csmith12 · February 7th, 2017, 02:32 PM

Been sitting...

Suspect tires first... then move on to more complex solutions. The forks can be ruled out with some work, tires are bit more tricky.

NinjaBraap · February 7th, 2017, 02:54 PM

Quote:

Originally Posted by csmith12

Been sitting...

Suspect tires first... then move on to more complex solutions. The forks can be ruled out with some work, tires are bit more tricky.

That's entirely possible, I'd need to ride it more to find out, which is hard as it isn't my bike. I'd just hate to see a newbie crash because it was something broken.

NinjaBraap · February 7th, 2017, 02:58 PM

Quote:

Originally Posted by Flying

Maybe the forks are misaligned instead? Check the height from the top of the fork tubes to the triple clamp.

I double checked the heights several times with my calipers. Both measured the same, plus the handlebars sit right on top of the forks like caps. Usually when reassembling ninja 250 front ends I just bolt on the handlebars and then let the forks set in gently (while on the tiptree stand so as not to bend the forks from the bikes weight), then measure with calipers to double check that the clearance is correct.

jrshooter · February 7th, 2017, 04:59 PM

you said the bike went down. i would loosen tripple clamps and axel and make sure the clamps are aligned and tighten it all up.
sometimes when a bike goes down things in the front get in a bind.
probably wont fix your issue, but something to be aware about.

NinjaBraap · February 7th, 2017, 05:16 PM

Quote:

Originally Posted by jrshooter

you said the bike went down. i would loosen tripple clamps and axel and make sure the clamps are aligned and tighten it all up.
sometimes when a bike goes down things in the front get in a bind.
probably wont fix your issue, but something to be aware about.

Yeah I already did that just from the installation of the ignition switch. This was post installation.

Motofool · February 7th, 2017, 05:31 PM

Quote:

Originally Posted by NinjaBraap

..........when turning the handlebars it tended to continue in the direction being turned and required pushing on the handlebar to keep from turning all the way into the direction being turned..........

If I read you correctly, I understand that the bike is over-steering.

Worn tires can do that, as stated above by @csmith12.
Bad steering head bearings can do that when supporting the weight of the front half of the bike.

Front versus rear heights that are off-design can cause that as well:
http://www.dirt-bike-secrets.com/oversteer.html

If you suspect the forks are bent, a straight edge and poor suspension may be able to confirm that.

When on both tires, the angle of the forks respect to a vertical line should be 27 degrees and the trail should be 84 mm.
Trail is the horizontal distance between the center of the front contact patch and an imaginary line extending from the steering head.
Is those two values are way off, the bike can become over-steering.

February 7th, 2017, 02:21 PM	#1
NinjaBraap NinjaBraap Name: Tom Location: Long Beach, California Join Date: Dec 2016 Motorcycle(s): 06 Ninja 636, 2016 Yamaha R3 (Street/Track), 2019 Ninja 400 Project Racebike Posts: 175 Blog Entries: 2	Possible bent forks. Recently test rode a 2007 Ninja 250 after replacing the ignition switch. Right off the bat noticed that when turning the handlebars it tended to continue in the direction being turned and required pushing on the handlebar to keep from turning all the way into the direction being turned. Since it wasn't my bike, and it had been sitting for about 6 months since it'd been ran last, I had no idea what it'd been like before, nor did the owner. Just from experience though I knew it wasn't right from riding every other bike ever, and from owning a 2004 Ninja 250 and 2008 Ninja 250 of my own. I immediately suspected bent forks, as the fork bearings weren't stiff and were working properly, and no other parts appeared to be damaged or bent in any way. Visually though the forks looked straight, there wasn't any leaking seals and the wear was even on the pads, so there wasn't any other indications that they were bent. The bike had been down from the previous owner (the bike's current owner is a new rider, and bought it last year), and someone had tried to steal the bike while it sat this winter, and kicked the bike over when they failed to unlock the ignition (why I was replacing the ignition switch). Long story short figured I'd get a second opinion. Any Ideas or thoughts are welcome, thanks everyone! __________________________________________________ Racer, Mechanic, Enthusiast. Vendor for Norton Motorsports Subscribe to my Instagram and YouTube: Instagram YouTube

February 7th, 2017, 02:32 PM	#3
csmith12 The Corner Whisperer Name: Chris (aka Reactor) Location: Northern KY Join Date: May 2011 Motorcycle(s): 2010 250 (track), 1992 250, 2006 R6 (street/track), 2008 R6 (track) Posts: Too much. MOTY 2015, MOTM - Nov '12, Nov '13	Been sitting... Suspect tires first... then move on to more complex solutions. The forks can be ruled out with some work, tires are bit more tricky. __________________________________________________ Goal: Shake A Million Hands \| Look through the corners \| Track Day Prep \| Closest track? \| The Mid-Ohio School
	1 out of 1 members found this post helpful.

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February 7th, 2017, 02:30 PM	#2
Flying ninjette.org sage Name: - Location: somewhere cold Join Date: Jun 2013 Motorcycle(s): 2010 Ninja 250 Posts: 596 Blog Entries: 1	Maybe the forks are misaligned instead? Check the height from the top of the fork tubes to the triple clamp.

February 7th, 2017, 04:59 PM	#6
jrshooter ninjette.org guru Name: john Location: placerville Join Date: Apr 2016 Motorcycle(s): ninja 300 Posts: 386	you said the bike went down. i would loosen tripple clamps and axel and make sure the clamps are aligned and tighten it all up. sometimes when a bike goes down things in the front get in a bind. probably wont fix your issue, but something to be aware about.