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PostPosted: Mon Dec 26, 2016 11:44 pm 
On the street
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Joined: Sun Dec 18, 2016 6:15 pm
Posts: 21
Location: Northern British Columbia
Country: Canada
Bikes owned: 72 GT750, 74 GT750, 75 T500, 76T500, 09 DR650
Does anyone know if better springs would improve the front end of these bikes? The existing ones felt kinda limp when I took them apart

-what is the stock spring length spec supposed to be? (the old ones measure 442mm)
-what is the stock spring rate?
-any recommendations for an uprated spring?

Is there anything else that can be done to improve these forks?


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PostPosted: Mon Dec 26, 2016 11:53 pm 
Moto GP
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Joined: Mon Nov 03, 2008 10:47 am
Posts: 6030
Location: Illinois
I don't have an answer on the spring, but the damping needs a major modification to change it. It's an old shuttle valve type design. Blanking off the old damping holes would be easy. It may be harder to replace the spring support rods with what we would consider to be conventional damper rods. I would speculate that it would not be too hard to machine later model damper rods or maybe GS damper rods with modern seals - as long as the fork tube bore is smooth enough stock.

If not, it may be necessary to convert GS750/1000 forks to work with a drum front wheel.

PostPosted: Tue Dec 27, 2016 2:53 am 
Moto GP
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Joined: Mon Dec 13, 2010 4:32 pm
Posts: 3321
Location: southwestern Pennsylvania
Country: USA
Bikes owned: 69 T350 thru 75 GT750
Cycle World magazine had an article about modifying the forks. Don’t know if this will work on the J models.

I have a stock & modified 75 GT750s. The GS-series forks on the modified bike are a huge improvement.

BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

GT750 2x75
GT550 72 project & 75
GT380 72
T500 73 project
T350 69, 71 & 72 project
T250 72
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE

PostPosted: Thu Dec 29, 2016 1:00 am 
Moto GP
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Joined: Sat Feb 07, 2009 12:43 am
Posts: 3186
Location: Ontario
Country: Canada
Bikes owned: GT750(Jx3,L,M,A,B),T500
You can fit progressive springs - the ones sold for the GT750 are for the later versions and need to be shortened for the J, or possibly you can match up the length from another model. The ones sold for the later GT750's (kit 11-1120 and 19.75 inches long) are actually for a Harley Davidson so finding something to fit the J should be possible. 8)


If at first you don't succeed, just get a bigger hammer !

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