modded gs frames

[timebombprod]

i was wondering if modding these frame to have a more upright fork position is something common or atleast done by people, when u look at it without the tank or the seat 80% of the frame says race to me except ofcourse up where the forks are at, also i dont know *@%^$*@%^$*@%^$*@%^$ about all the frame geometry and stuff so dont take my complete word for it, now i know theyre not meant for dropping a knee leaning so i guess you have to do other things too but i was just curious about it and what people think about them.

[roeme]

Not really versed in this matter, but before even thinking about modifying rake, I'd stiffen up the frame, suspension, all that jazz. At least that's what I constantly think of when changing between my 2014 Guzzi and the 1978 GS's I've put "M" handlebars on, which makes it a little bit "racy-er". And the Guzzi ain't a particular stiff frame to begin with, methinks. Both bikes have a similar rake angle.

[timebombprod]

Not really versed in this matter, but before even thinking about modifying rake, I'd stiffen up the frame, suspension, all that jazz. At least that's what I constantly think of when changing between my 2014 Guzzi and the 1978 GS's I've put "M" handlebars on, which makes it a little bit "racy-er". And the Guzzi ain't a particular stiff frame to begin with, methinks. Both bikes have a similar rake angle.

yeah im just wondering if its something people do i dont plan on doing it (not for a very long time atleast) but id like to see some pictures or something and get opinions on the matter

[GregT]

By the time you've raised the rear end for ground clearance while keeping the forks at the standard height - again for clearance - the rake and trail figures are getting close to modern norms. Our GS1000 on 17in wheels with long shocks measured up at 25 deg rake and 96mm trail. Similar to a late big Triumph - but longer in the wheelbase. Much quicker steering than stock but still stable.
Frame stiffening is definitely required with this geometry. There have been a lot of posts on here and elsewhere about that subject. Some are even useful.

I was looking at another local GS1000 last week. It's known to go quite well - it's approaching the lap times set by our bike before it was parked up. But the stiffening has been done in a quite different way from how I did ours....There's room for differences. More than one way to get the same result.

[80GS1000]

+1 to GregT. With the correct suspension changes you can approach modern chassis geometry (rake/trail) numbers.

http://oldskoolsuzuki.info/archives/315

I have braces D and E on my GS1000 as part of the monoshock conversion and can confirm that this stiffens up the critical area above the swingarm pivot. Helps to remove that "hinged in the middle" feeling when cornering hard at speed with the stock GS frame.

[GregT]

The full X isn't required. A single diagonal in the right place turns it into two triangles anyway. The bike I mentioned had the curves in the top frame tubes above the pivot sheeted in. Again unneccessary IMO. I did a lot of lightweight gussetting on the lower part of our frame as close observation of the bike under high cornering loads and power told me the frame was "scissoring" - the front downtubes were moving in relation to each other - one up, one down.
Tying the front of the engine in better also helps here. Thick alloy engine plates and close fitting bolts work well.