Fork brace for OEM front end - Ex-500.com - The home of the Kawasaki EX500 / Ninja 500R
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post #1 of 14 (permalink) Old 12-1-2019, 11:10 AM Thread Starter
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Fork brace for OEM front end

If anyone is interested Flatland Racing in Emporia, KS made these. The biggest difference I noticed was that the feedback/feel from the front was greatly improved. I'm not sure what they cost as they were part of a deal when I sold a project bike to a friend, who then commissioned these to be made. He said he gave them $300 for the pair. The one-piece design requires sliding the forks out of the triple clamps for installation, but it also makes them stronger than other split designs I've seen. Made from billet aluminum they really are a nice bit of kit. I got confirmation that they would be happy to make more before I posted. Feel free to contact them.
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post #2 of 14 (permalink) Old 12-1-2019, 5:36 PM
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Those are nice looking pieces. Gen 2 has a 1mm larger fork than Gen1. I'm not sure about the C-C measurement, but, given how precisely fork braces must fit, I'd say that 1mm difference means that each generation would require a specific brace.

Your observations are interesting. Everywhere you go there seems to be debate as to how effective fork braces are. There's general agreement that some bikes (such as the C10 Concours and the 1200 Bandit) really benefit from them, while others, not so much. I always thought the forks on the ex-500 were spindly enough to benefit, but it's been written here that they increase chatter on hard cornering. I expect that for slightly less aggressive riding it could be beneficial.
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post #3 of 14 (permalink) Old 12-1-2019, 7:20 PM Thread Starter
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Regarding chatter, the only time I noticed any was before we had the forks refreshed & resprung early in the development of the bike for endurance. To give you an idea of setup the bike already had gold valve emulators. I run a Pirelli SC2 slick 120/70 up front with FOG bones and a Penske double clicker on the rear. Woodcraft clip-ons with no rise puts rider weight bias closer to the front too. The main reason for the 120/70 was because I have plenty of take-offs from my bigger bike racing and I'm too lazy to try and keep everything segregated. The only guys I have trouble keeping up with are on the new Ninja 400. Just one test so far after installation at Hallett, OK a few weeks ago. Conditions were quite cool and partly cloudy, but I was able to better my previous time by almost a full second while on the same tires we used during our last 6hr endurance. So may variables can contribute to chatter and I know this forum offers plenty of knowledge on the EX500. I'm the only rider on the team that has ridden it with the new brace, but I got one for my daughter's sprint bike too. We'll see how she likes it. If issues appear I'll do my best to keep the forum informed.

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post #4 of 14 (permalink) Old 12-1-2019, 10:45 PM
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Excellent! I'll be looking forward to see if you have further comment on this.
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post #5 of 14 (permalink) Old Yesterday, 4:43 AM
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Indeed those are very nice looking pieces. Very solid lockup, it would seem. Q: Have you perchance drilled the bottom of your slider so that both sides have an axle pinch bolt? Yamaha used this to tighten up their front ends. As well, they used a split collar (similar to these braces) on the upper triple where it clamped to the steerer tube of the lower clamp. The EX is really weak in that regard.

Most commercial braces have a spacing adjustment and this requires some careful setup. Best is to leave them slightly loose, then stroke spring-less forks through their travel taking note of any stiction, adjusting as needed. However, a lot of these went onto forks that were hashed and needed new bushings in the first place, so I suppose that some were indeed binding as a result of that wear and improper brace setup, thus, chatter.

As to the EX, fork tube diameter increased, but I have never measured the slider diameter for difference between generations.

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post #6 of 14 (permalink) Old Yesterday, 11:18 AM Thread Starter
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Quote:
Originally Posted by po18guy View Post
... Q: Have you perchance drilled the bottom of your slider so that both sides have an axle pinch bolt? ...
There are axle pinch bolts already in the bottom of the forks. As far as fit and stiction. I sent the machine shop my entire front end assembly. They referenced the center-to-center measurement directly from the triple clamp. The brace fits like a glove.

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post #7 of 14 (permalink) Old Yesterday, 11:49 AM
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Being a racer and a CNC machinist I though a fork brace a good Idea, until I made one. The problem come from a degree of precision lacking in the fork assembly. The slider housing is a cast piece that is hand ground for appearance only ,and is neither round or tru to location/ (remember Machinist think).
Forging ahead I made several, only to find them unneeded . Seem the wobbly front compliments the wobbly frame and one cancels out the other . Just as Viabration dampners don't help a ex, and can even worsen the problem. for braces seem to do the same.

Hears one I made and finally gave to a street poser, who loved the look.

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post #8 of 14 (permalink) Old Yesterday, 1:52 PM Thread Starter
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Appreciate the feedback, FOG. I like the change a fork brace made. I've endurance raced a Ninja 250 several times as well and absolutely hated the flexing characteristics of it. On the spectrum of wobbly to stiff the EX500 is closer to the 250 than the modern peremeter frames of today's sportbikes, but I won't accept that it can't be improved.

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post #9 of 14 (permalink) Old Yesterday, 4:47 PM
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Appreciate the feedback, FOG. I like the change a fork brace made. I've endurance raced a Ninja 250 several times as well and absolutely hated the flexing characteristics of it. On the spectrum of wobbly to stiff the EX500 is closer to the 250 than the modern peremeter frames of today's sportbikes, but I won't accept that it can't be improved.
Rots of ruck, triedfor 12 years within the context of box stock and gave up. Just learned the gynamstics to ride it.

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post #10 of 14 (permalink) Old Yesterday, 6:37 PM
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Quote:
Originally Posted by Tornado Bait View Post
There are axle pinch bolts already in the bottom of the forks. As far as fit and stiction. I sent the machine shop my entire front end assembly. They referenced the center-to-center measurement directly from the triple clamp. The brace fits like a glove.
Both sides have pinch bolts? That's cool.

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post #11 of 14 (permalink) Old Yesterday, 7:12 PM
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^What do you mean? Don't the gen 1's have pinch bolts on both sides?

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post #12 of 14 (permalink) Old Yesterday, 9:58 PM Thread Starter
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Quote:
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Rots of ruck, triedfor 12 years within the context of box stock and gave up. Just learned the gynamstics to ride it.

Fog
Thanks, you were spot on with the geometry change from your FOG Bones. And I was intuitively drilling the airbox when I came across this site during an internet search and your "mod" for that. I'm just an old racer too, and stubborn. I won't be satisfied until I give it a try myself.

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post #13 of 14 (permalink) Old Today, 2:12 PM
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You'd need to stiffen both fork & frame. Otherwise stiffer fork will just cause more bending in frame for same amount of stress. If you've got instruments or can detect where frame's bending, you'll find more torsional twisting in rear backbone area above where removable section bolts in. To stiffen frame you'd need to add about 25-lbs of braces and gussets to frame to do any good.

One thing I was considering was keeping just rear engine-mount section with mounting for swingarm and removing everything else. Then replacing with larger-diameter 25mm chromoly tubing. Will end up re-creating Ducati trellis frame with engine as stressed-member by time re-design was completed.
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post #14 of 14 (permalink) Old Today, 2:47 PM
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Quote:
Originally Posted by fog View Post
Being a racer and a CNC machinist I though a fork brace a good Idea, until I made one. The problem come from a degree of precision lacking in the fork assembly. The slider housing is a cast piece that is hand ground for appearance only ,and is neither round or tru to location/ (remember Machinist think).
Forging ahead I made several, only to find them unneeded . Seem the wobbly front compliments the wobbly frame and one cancels out the other . Just as Viabration dampners don't help a ex, and can even worsen the problem. for braces seem to do the same.

Hears one I made and finally gave to a street poser, who loved the look.

FOG
I tried a fork brace on the EX (on the track) back in the day, and decided against it as well. It did make the front chatter, and also changed the overall feel/flex of the bike. Ran it a few times and removed it.

The EX was/is a flexy flier, and removing one part of the flex has an effect on all the other flex. I felt it was better to just roll with it and not fight it.
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