Do I need new forks?

guitar · July 19th, 2020, 10:02 PM

tl;rd:
Can I sand out the dents in my forks or do I have to buy new (to me) ones?
pics of said dents:
https://imgur.com/a/N2RkX48

Hi all,

I think this is my first post on this forum but I've been lurking since about this time last year when I started having problems with my ninja.

I bought an '06 ninja 250 with ~11k miles about 2 years ago. The PO told me he rear-ended someone but that the only damage was to the front wheel fender. I believed him, not knowing any better myself. I could hardly ride at that point much less diagnose mechanical issues that could result from a low speed accident. I had a local shop check the bike out when I got it back to town. They told me it had leaking fork seals but was otherwise in good shape. That shop told me they were too busy and sent me to the Kawasaki dealership in town. They did the fork seals and I had no problems for about 7 months and 5k miles.

After that though, I noticed the seals had started leaking again, but the bike also wasn't starting. I figured the latter was more important and took it back to the shop to take care of it. They struggled to find the issue and nearly 8 months later still never figured it out imo. They got the bike running, but it was more like they rigged it to get it running. I just got my carbs back from Ducatiman btw so I'm happy to know that at least my carbs are in good shape. Anyway, when I eventually got the bike back a few months ago, I got it to start once or twice and was right back where I started. Frustrated, I just let the bike sit and tended to other life matters.

A few weeks later, I was looking my ninja over and saw the entire caliper, rotor, and wheel covered in oil. It was like someone turned on a faucet.

I've been researching how to replace the fork seals for a few weeks and have been avoiding making another redundant thread. I now have my fork seals, and all the tools I need to do a diy fork seals job. Today though, as I was gathering the tools and parts to actually start the job, I thought I would look my forks over really closely. I confirmed that they are still leaking quite heavily, but came across a number of small dings in the forks.

So now I come to you, wondering if I need to just purchase new forks or if I can use some 2000 grit sandpaper and sand the dings out. I'm looking at eBay for used forks. Looks like around $80 for a set of straight forks with good seals. I'm beginning to pour more money into this than I was hoping to. I'm starting to wonder if I need to cut my losses and sell the bike. Any help or insight is greatly appreciated.

edit: I tried to add the photos but my girlfriends camera takes really high resolution pictures so they took up the entire page. Here is the imgur link

https://imgur.com/a/N2RkX48

tl;rd:
Can I sand out the dents in my forks or do I have to buy new (to me) ones?

Triple Jim · July 20th, 2020, 05:15 AM

I'd smooth that carefully with some 400 grit wet/dry sandpaper backed with a piece of metal and use it without worry. don't try to remove the dents, just smooth them a little until you can't feel any sharp edges.

guitar · July 20th, 2020, 10:53 AM

Thanks Jim. I’ll pick some up today and see what I can get going. I’m assuming I’ll utilize the cross hatch method recommended on the 250 FAQ.

Any ideas on what caused the seals to leak this time around? I’m thinking that not cleaning them is probably what did it. But when I get the forks apart to replace the seals I’ll inspect the bushings for problems too.

Looking at the parts diagram, I see two different bushings on one fork; could either of them cause a seal failure? The FAQ only mentions the one copper bushing.

Triple Jim · July 20th, 2020, 01:32 PM

All you need to do is take off any sharp edges around those dings. You shouldn't be sanding a large area around them with a cross hatch pattern or anything like that. Don't try to remove the dings, just make them smooth so the seals don't get damaged.

Seals can just fail... they don't always need a reason.

DannoXYZ · July 20th, 2020, 11:14 PM

Hi Sage and welcome to Ninjette!

If fork seals were sliding over those dents with sharp edges, that could lead to premature wear.

Yeah, you don't want to sand away surrounding metal until everything is as low as the dents, you'll open up a huge gap and seals won't... seal!

Just take away sharp-edges so it won't gouge out your new seals. I've used precision jeweler's files to gently take away anything that's raised. Then smooth area with 2000-grit sandpaper.

Good luck!

guitar · July 26th, 2020, 04:58 PM

Finally made the time to get out there and pull the forks. The wiki says if the copper is coming through then its time to get new bushings. I suspect that the forks were bent in the PO's accident.

pics of the four bushings:
https://imgur.com/a/doutO5Z

New bushings are almost as much as a pair of used forks on ebay. I'm thinking I'll avoid the risk of replacing the bushings on possibly bent forks. Peace of mind sort of thing.

DannoXYZ · July 26th, 2020, 06:08 PM

Put fork tubes on V-blocks and spin them. That'll show you how much runout there is. Typically bend is just under lower triple-clamp, where torque from impact is highest. Luckily, that means seals and bushings don't have to ride over bend.

One thing that may help longevity is to get some covers like on '08-12 250 to deflect rocks and anything that may damage surface of tubes. I've also seen accordion covers like on dirt-bikes.

July 19th, 2020, 10:02 PM	#1
guitar ninjette.org newbie Name: Sage Location: CA Join Date: Jul 2019 Motorcycle(s): Ninja EX250 Posts: 3	Do I need new forks? tl;rd: Can I sand out the dents in my forks or do I have to buy new (to me) ones? pics of said dents: https://imgur.com/a/N2RkX48 Hi all, I think this is my first post on this forum but I've been lurking since about this time last year when I started having problems with my ninja. I bought an '06 ninja 250 with ~11k miles about 2 years ago. The PO told me he rear-ended someone but that the only damage was to the front wheel fender. I believed him, not knowing any better myself. I could hardly ride at that point much less diagnose mechanical issues that could result from a low speed accident. I had a local shop check the bike out when I got it back to town. They told me it had leaking fork seals but was otherwise in good shape. That shop told me they were too busy and sent me to the Kawasaki dealership in town. They did the fork seals and I had no problems for about 7 months and 5k miles. After that though, I noticed the seals had started leaking again, but the bike also wasn't starting. I figured the latter was more important and took it back to the shop to take care of it. They struggled to find the issue and nearly 8 months later still never figured it out imo. They got the bike running, but it was more like they rigged it to get it running. I just got my carbs back from Ducatiman btw so I'm happy to know that at least my carbs are in good shape. Anyway, when I eventually got the bike back a few months ago, I got it to start once or twice and was right back where I started. Frustrated, I just let the bike sit and tended to other life matters. A few weeks later, I was looking my ninja over and saw the entire caliper, rotor, and wheel covered in oil. It was like someone turned on a faucet. I've been researching how to replace the fork seals for a few weeks and have been avoiding making another redundant thread. I now have my fork seals, and all the tools I need to do a diy fork seals job. Today though, as I was gathering the tools and parts to actually start the job, I thought I would look my forks over really closely. I confirmed that they are still leaking quite heavily, but came across a number of small dings in the forks. So now I come to you, wondering if I need to just purchase new forks or if I can use some 2000 grit sandpaper and sand the dings out. I'm looking at eBay for used forks. Looks like around $80 for a set of straight forks with good seals. I'm beginning to pour more money into this than I was hoping to. I'm starting to wonder if I need to cut my losses and sell the bike. Any help or insight is greatly appreciated. edit: I tried to add the photos but my girlfriends camera takes really high resolution pictures so they took up the entire page. Here is the imgur link https://imgur.com/a/N2RkX48 tl;rd: Can I sand out the dents in my forks or do I have to buy new (to me) ones? Last futzed with by guitar; July 20th, 2020 at 10:56 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
better then forks?	allanoue	General Motorcycling Discussion	11	March 24th, 2016 05:49 AM
How do i get this out of my forks?	Graugaard	2008 - 2012 Ninja 250R Tech Talk	33	February 14th, 2013 06:20 PM
Distance between forks.	nickadolph	2008 - 2012 Ninja 250R Tech Talk	5	March 15th, 2012 08:53 PM
88-07 Forks	SRTie4k	Motorcycle-related	0	October 9th, 2010 06:31 AM
Other Compatible Forks?	00v_Lucky	2008 - 2012 Ninja 250R Tech Talk	6	September 18th, 2010 10:19 PM

July 20th, 2020, 05:15 AM	#2
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	I'd smooth that carefully with some 400 grit wet/dry sandpaper backed with a piece of metal and use it without worry. don't try to remove the dents, just smooth them a little until you can't feel any sharp edges.

July 20th, 2020, 10:53 AM	#3
guitar ninjette.org newbie Name: Sage Location: CA Join Date: Jul 2019 Motorcycle(s): Ninja EX250 Posts: 3	Thanks Jim. I’ll pick some up today and see what I can get going. I’m assuming I’ll utilize the cross hatch method recommended on the 250 FAQ. Any ideas on what caused the seals to leak this time around? I’m thinking that not cleaning them is probably what did it. But when I get the forks apart to replace the seals I’ll inspect the bushings for problems too. Looking at the parts diagram, I see two different bushings on one fork; could either of them cause a seal failure? The FAQ only mentions the one copper bushing.

July 20th, 2020, 01:32 PM	#4
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	All you need to do is take off any sharp edges around those dings. You shouldn't be sanding a large area around them with a cross hatch pattern or anything like that. Don't try to remove the dings, just make them smooth so the seals don't get damaged. Seals can just fail... they don't always need a reason.

July 20th, 2020, 11:14 PM	#5
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	Hi Sage and welcome to Ninjette! If fork seals were sliding over those dents with sharp edges, that could lead to premature wear. Yeah, you don't want to sand away surrounding metal until everything is as low as the dents, you'll open up a huge gap and seals won't... seal! Just take away sharp-edges so it won't gouge out your new seals. I've used precision jeweler's files to gently take away anything that's raised. Then smooth area with 2000-grit sandpaper. Good luck!

July 26th, 2020, 04:58 PM	#6
guitar ninjette.org newbie Name: Sage Location: CA Join Date: Jul 2019 Motorcycle(s): Ninja EX250 Posts: 3	Finally made the time to get out there and pull the forks. The wiki says if the copper is coming through then its time to get new bushings. I suspect that the forks were bent in the PO's accident. pics of the four bushings: https://imgur.com/a/doutO5Z New bushings are almost as much as a pair of used forks on ebay. I'm thinking I'll avoid the risk of replacing the bushings on possibly bent forks. Peace of mind sort of thing.

July 26th, 2020, 06:08 PM	#7
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	Put fork tubes on V-blocks and spin them. That'll show you how much runout there is. Typically bend is just under lower triple-clamp, where torque from impact is highest. Luckily, that means seals and bushings don't have to ride over bend. One thing that may help longevity is to get some covers like on '08-12 250 to deflect rocks and anything that may damage surface of tubes. I've also seen accordion covers like on dirt-bikes.