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help advice needed

Posted: Sun Jun 11, 2017 4:15 pm
by manxgtjohn
so gt750 1977 whats the widest swing arm and rear i can get in a standard frame if any one can point me in the right direction to which arm to use that would be a big help i was going to do a chassis change but just got a nice standard frame bought tonight so a week to get here and i can start

Re: help advice needed

Posted: Mon Jun 12, 2017 12:14 am
by Alan H
It's not the widest swing arm that needs looking at, it's how much clearance between chain and tyre.
You can't fit a wider tyre to any bike if there's no clearance. You then have to offset the drive sprocket to line up with the new wheel sprocket and all the farting about that entails.
I've a Dresda swing arm on my 750B, which allows a slightly wider tyre - I'll have a look later what size, but these are few and far between.
Of course anything can be fitted to anything if you have lots of cash available!

Re: help advice needed

Posted: Mon Jun 12, 2017 10:44 am
by Zunspec4
Hello John,

Unless you have you heart set on modifying your bike in some sort of customising project I would offer the opinion that you do not need big wide tyres on a GT750. The power output is pretty modest in todays terms and combined with the vast superiority of modern tyres compared to old you will have plenty of grip to ground those freshly re-chromed silencers :D

Cheers Geoff

Re: help advice needed

Posted: Mon Jun 12, 2017 1:05 pm
by manxgtjohn
the bike that i have bought is basically scrap
you can push your finger through the frame the tanks split pipes are rotten
so really i have a motor & electrics so a custom project is my only option and to be honest iv had customs from 1979 standard bikes dont do it for me

Re: help advice needed

Posted: Mon Jun 12, 2017 3:29 pm
by Suzukidave
Check out this one for some inspiration viewtopic.php?f=21&t=7781" onclick="window.open(this.href);return false;

Re: help advice needed

Posted: Mon Jun 12, 2017 4:56 pm
by manxgtjohn
thanks suzukidave cracking build page you got one on your build ?

Re: help advice needed

Posted: Mon Jun 12, 2017 7:10 pm
by Suzukidave
It was lost when the Sundial site refreshed a couple of years ago .

Re: help advice needed

Posted: Mon Jun 12, 2017 7:12 pm
by Suzukidave
There is also this build . also a Rossie with a Yamaha frame viewtopic.php?f=21&t=12161" onclick="window.open(this.href);return false;

Re: help advice needed

Posted: Tue Jun 13, 2017 12:19 am
by Mgmark
A GS1100 alloy swingarm will fit the GT frame with some modification. The pivot shaft is 16mm , which is larger than the GT 14mm so the frame holes will need to be modified. The GS pivot shaft will need to be shortened about an inch also. The GS swingarm pivot width is the same as the GT.
The GS1100 arm is about 3" longer in weelbase, but almost all of that can be removed from the front section and the arm reassembled to near stock length. Personally I don't like the extended wheelbase look on the GT, I prefer the stock length and the bike bike steers slow enough already without lengthening the wheelbase.
The shock absorber mounts are wider on the GS swingarm than the frame so that will need to be addressed. The chainguard and front mount will need to be changed also.

After the mods it will the slot into the GT frame like it was made for it. The best bit is a GS1000 spoked rear wheel and brake setup will then bolt right in with the 1100 spacers. The GS swingarm will take a wider wheel than the GT and I will be running wider alloy spoked rims front and back. The alloy SA is about 3.5 lbs lighter than the GT part before shortening.

Mark