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Author Topic: Gt650R Race Mods  (Read 2835 times)

CHC Racing

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Gt650R Race Mods
« on: August 05, 2015, 11:45:24 PM »

Hey,

We are building a GT650 2007 model for racing and so far we have fitted a GSXR750 rear shock with a Hyperpro spring. Has anyone any experience with swapping out forks? Such as if the forks are the same diameter and length should they work if taken from a differen bike such as 675 Truimph?

Any help is appreciated :)
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umop-ǝpisdn

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Re: Gt650R Race Mods
« Reply #1 on: August 06, 2015, 09:43:12 AM »

I looked a few years back to try and find another, better quality bike that used 51mm forks, but couldn't find anything :(

Again though, Racetech make complete inserts for the Hyosungs. You just need to specify what spring rate you want. They even have a tool somewhere on their site that helps you choose what spring rate you need based on your weight.
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I used to be a sensitive, new age guy, but times have changed and now I am more of a caring, understanding, ninties type.

CHC Racing

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Re: Gt650R Race Mods
« Reply #2 on: August 06, 2015, 01:06:25 PM »

Yeah we are having a similar problem, we have a 675 Triumph and measured it and they are 49.8mm so we were wondering if the Hyo headstock clamps would tighten enough to hold them securely? We saw on the forum a guy had put a 675 swing arm in, which we were planning to do, so would be good if it was Triumph for both, purely for product sourcing.

We say the race tech front ends, and heard they are good, front wheel gives us bother when changing it, as it never seems to line up and is a real fighting match to try and get it in quickly for race changes, so new forks would help with that also
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The_Phil

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Re: Gt650R Race Mods
« Reply #3 on: September 05, 2015, 12:29:37 AM »

according to this ebay item there are a few bikes with 51mm forks
http://www.ebay.com.au/itm/281740831491?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

"GT650R RC8 '09+ ZX6R RSV 1000R RSV4"

I dont know about the distance between tripleclamps though, that may be an issue. Ill see if i can measure the RC8 i have here.
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The_Phil

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Re: Gt650R Race Mods
« Reply #4 on: September 05, 2015, 01:07:19 AM »

KTM RC8 51mm forks, approx 260 (across the top tripleclamp, outside fork to outside fork.)
174mm between triple clamps (top of bottom clamp to bottom of top clamp)
about 150 to 160 inside to inside across the axle (hard to tell with the wheel in)

Can anyone give me the measurements of a GT650R? im not near my bike at the moment.

2015 KTM 690 duke has 51mm forks, 2014 KTM 390 Duke has 50.8mm forks
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umop-ǝpisdn

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Re: Gt650R Race Mods
« Reply #5 on: September 05, 2015, 02:45:26 AM »

It might be easier to get the complete front end from something more sport oriented, like a gsxr and use all the GSXR gear, wheel, axle, brakes, triple clamps.. everything.. and then just press out the pin that goes up through the steering stem and have a pin made that is the same diameter as the hyo pin and fits hyo head stem bearings.

Racetechs may end up cheaper, but you've still got the stock, very heavy, Hyosung front wheel. The GSXR wheel would be a lot lighter and unsprung weight is everything.
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The_Phil

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Re: Gt650R Race Mods
« Reply #6 on: September 05, 2015, 06:23:36 AM »

But if the forks are a direct swap you get brakes and a wheel as a bonus with less work.
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umop-ǝpisdn

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Re: Gt650R Race Mods
« Reply #7 on: September 05, 2015, 10:07:05 AM »

I'm not so sure though. The axle width would have to be the same. I'd rather have a machined steering stem than a machined axle. Stresses and all.
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I used to be a sensitive, new age guy, but times have changed and now I am more of a caring, understanding, ninties type.

The_Phil

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Re: Gt650R Race Mods
« Reply #8 on: September 07, 2015, 02:21:47 AM »

if the distance between the forks is the same and the fork diameter is the same then there would be no machining required.
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The_Phil

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Re: Gt650R Race Mods
« Reply #9 on: November 05, 2015, 06:49:00 AM »

i can confirm the spacing on the front forks is a direct match for the hyo in width.
The hyo triple just slips right on top without an issue.
not sure about the distance from top to bottom triple as the forks do have some taper.
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