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Author Topic: Hayabusa forks on CB750. What do I need?  (Read 2555 times)

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Offline 5thofhonda

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Hayabusa forks on CB750. What do I need?
« on: September 02, 2015, 08:01:11 PM »
A deal came up and I have the opportunity to pick up some first gem (99-07) Hayabusa forks, trees, stem and brake caliper for next to nothing.  I've called Cognito Moto and they've said it has been done, but some of the details eluded me. Can anyone shed some light for me?  I've done searches and the people that have done it didnt post specifics. Looking to keep the stock wire wheel up front as well.
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Offline SOHC4 Cafe Racer Fan

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Re: Hayabusa forks on CB750. What do I need?
« Reply #1 on: September 02, 2015, 08:58:56 PM »
Cognitomoto makes turnkey parts (hubs, triples, etc.) for many modern USD forks including CBR1000RR/CBR600RR/GSXR1000/750/600.  I don't think they make anything for the 'Busa.

I have seen several 'Busa fork conversions here on the forum.  Run a search and you should find more than a few build strings.  It usually involves sourcing a certain model Harley hub.
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1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
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"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline 5thofhonda

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Re: Hayabusa forks on CB750. What do I need?
« Reply #2 on: September 03, 2015, 07:07:29 AM »
I called them to see if any of their GSXR stuff was compatible and they said "kind of", basically, but with some tweaking. I have performed searches and have come up empty. Either the wrong CB, or the right CB with no specifics.
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Offline sinister902

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Re: Hayabusa forks on CB750. What do I need?
« Reply #3 on: September 03, 2015, 10:23:44 AM »
the reason the answer was "kind of" was because the hayabusa and TL models are unique in diameter at the lower triple clamp (55mm). most GSXR are 54mm lower. all top diameters are 50mm but TL and 'busa forks stock are 214mm apart while GSXR are 207mm apart. I am not positive off-hand but axles may also be different in length but diameter might be the same.

The closest Cognito setup to working with the 'busa parts would be a cognito hub to lace up a stock 19" rim, using the axle and lower tree from a GSXR1000-K1 or K2, or GSXR750-K0 or K3 since those are the only other forks that use the 320mm rotor diameter. this would allow you to use the cognito top triple tree and stem swap. you would have to machine the GSXR1000/750 lower triple fork clamps from 54mm to 55mm to accept the 'busa forks.

Other option is to get the cognito hub, and get conversion bearings from allballsracing to just bolt on the 'busa forks/triples.....use the 'busa axle and have custom spacers made to center the cognito hub. lace to your stock rim and then you should be set.

this chart is very helpful

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Offline 5thofhonda

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Re: Hayabusa forks on CB750. What do I need?
« Reply #4 on: September 03, 2015, 10:58:07 AM »
Awesome. Thank you, sir. Although someone on CL just offered me a complete pets bike GSXR 600 for about the same as the set of busa forks. Hopefully the VIN doesn't come back hot
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Offline SOHC4 Cafe Racer Fan

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Re: Hayabusa forks on CB750. What do I need?
« Reply #5 on: September 03, 2015, 11:00:16 AM »
Go with the GSXR.  It is bolt ON and if you want spokes you can used the Cognito hub.  Also, if you want to preserve stock offset, Devin will machine you a set of triples.

The Busa conversion is definitely more involved:
http://www.thechopperunderground.com/forum/index.php?showtopic=32232&hl=justin
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1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline 5thofhonda

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Re: Hayabusa forks on CB750. What do I need?
« Reply #6 on: September 03, 2015, 11:35:43 AM »
Scratch the complete 600, turns out it's a roller but may still be worth it.

Are there any advantages or disadvantages to keeping the GSXR offset? Bike is a hard tail not a cafe.
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Offline sinister902

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Re: Hayabusa forks on CB750. What do I need?
« Reply #7 on: September 03, 2015, 11:51:43 AM »
Quote from: 5thofhonda on September 03, 2015, 11:35:43 AM
Scratch the complete 600, turns out it's a roller but may still be worth it.

Are there any advantages or disadvantages to keeping the GSXR offset? Bike is a hard tail not a cafe.

if the bike is a hardtail the discussion on advantages or disadvantages is moot. might as well save the cash and just use the GSXR triples as-is with some bearings from allballsracing. bearings should be about $55-60 for top and bottom tapered roller bearings to fit the GSXR stem in the CB frame.
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Offline SOHC4 Cafe Racer Fan

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Re: Hayabusa forks on CB750. What do I need?
« Reply #8 on: September 03, 2015, 03:38:53 PM »
It's more about preserving the stock CB offset.  The offset is reduced on modern forks.  If you couple that with different size wheels, you can have significant effects on the bike's stability. 
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1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline calj737

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Re: Hayabusa forks on CB750. What do I need?
« Reply #9 on: September 03, 2015, 08:10:56 PM »
A small correction: the 750 stem and gsxr stem are differenet lengths, so you'll need to do a stem swap to mount the gsxr front end. Offset changes notwithstanding...
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Offline 5thofhonda

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Re: Hayabusa forks on CB750. What do I need?
« Reply #10 on: September 04, 2015, 03:33:18 PM »
Well thank you for all the replies. I ended up finding a set of 04/05 GSXR 750 forks, lower triple, brakes and cortex clip ons for $160.  Heading to pick them up in a bit.
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Offline SOHC4 Cafe Racer Fan

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Re: Hayabusa forks on CB750. What do I need?
« Reply #11 on: September 05, 2015, 06:30:21 AM »
Great choice and price.
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1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline 5thofhonda

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Re: Hayabusa forks on CB750. What do I need?
« Reply #12 on: September 05, 2015, 08:26:02 AM »
He also threw in a steering damper. I'll have to figure that out later.
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