Tarozzi fork brace fitment, 6 part #'s for the same dimension braces????

[Chuck78]

I am trying to get a Tarozzi fork brace for my 81 GS650G dual disc forks that I am fitting to my single disc 77 GS750 to do the twinpot mod. On both websites that I have found to order them from, FromThePast and another (in Australia I believe it was), they only seem to list the 1983 GS650GT in their guide. This bike has 37mm fork legs according to their charts. The GS650 forks I have are 35mm, to bolt directly into the triple clamps of my 35mm GS750.

Since they have no listing for the 35mm GS650, I went through all their specs and came up with 5 or 6 application part #'s that all have the same mounting specs!
(EDIT - posting photos, I saw some are flat and some are arched)

24-0028 / 1978 GS500E / 35mm tube - 58mm mounting diameter - 175mm mounting center distance arched center
24-0029 / 1978 GS550E / 35mm tube - 58mm mounting diameter - 175mm mounting center distance
24-0030 /1983 GS650GT/ 37mm tube- 58mm mounting diameter - 175mm mounting center distance arched center
24-0033 / 81-82 GS500 / 35mm tube - 58mm mounting diameter - 175mm mounting center distance arched center
24-0034 / 81-82 GS550 / 35mm tube - 58mm mounting diameter - 175mm mounting center distance
24-0040 / 1979 GS750E / 35mm tube - 58mm mounting diameter - 175mm mounting center distance arched center


As far as the 35 vs 37mm, I now realize that to install, since there is very little area to clamp them on below the dust boot, you remove the dust boot to clamp the fork brace on where the dust boot is intended to sit, and then the top of the brace is machined identical to the fork to accept the dust boot. It makes sense to me that the 83 GS650GT 37mm leg for brace would be the exact same as the other 5 braces I listed, but the Suzuki fork boot dust shield would have a larger top inner diameter and the same 58mm diameter where it snaps to the fork, as their chart shows. Can anyone else see any reason that the 37mm leg version would be different?


It would appear that all of them are similar shape, and none specify an arched center to clear a larger tire. I think I am good ordering any of the 5 with the 35/58/175 listing, but I have not heard back from FromThePast to verify. Any clues????

 

[Chuck78]

24-0028 / 1978 GS500E / 35mm tube - 58mm mounting diameter - 175mm mounting center distance

24-0029 / 1978 GS550E / 35mm tube - 58mm mounting diameter - 175mm mounting center distance

24-0030 /1983 GS650GT/ 37mm tube- 58mm mounting diameter - 175mm mounting center distance

 

[Chuck78]

24-0033 / 81-82 GS500 / 35mm tube - 58mm mounting diameter - 175mm mounting center distance

24-0034 / 81-82 GS550 / 35mm tube - 58mm mounting diameter - 175mm mounting center distance

24-0040 / 1979 GS750E / 35mm tube - 58mm mounting diameter - 175mm mounting center distance

 

[Chuck78]

After posting all of these photos, the only differences I can see is that some of them have a flat bottom center piece, and some have a slight arch cast into them while retaining a flat top. I think my best bet is the arched piece, although it may be marginally less rigid. I am going up to a 110/90 front tire, but dropping my rim size from stock 19" down to 18" in order to keep a similar outside diameter for speedometer accuracy and keeping near stock suspension geometry with ride heights, angles, and ground clearance.

 

[Charlie G]

I was looking for a brace for my 650g last week and was facing the same delema. I think I'll go with the 24-0029 for the GS550, in an attempt to have the dust boot from a 650g fit. If you hear back from them post a response here please.

cg

 

[salty_monk]

The GS1000 brace fits on an 1100 fork but the gap between fender & brace is bigger in the middle...

 

[Steve]

I am going up to a 110/90 front tire, but dropping my rim size from stock 19" down to 18" in order to keep a similar outside diameter for speedometer accuracy and keeping near stock suspension geometry with ride heights, angles, and ground clearance.

Are you more interested in keeping the "accuracy" that you have or would you like to make it closer to "correct"? :-k

The stock 90/90-19 is rather innaccurate on most of these bikes. Installing a 100/90-19 makes it very close. I have checked 4 of our 5 bikes with a GPS and found that at 60 MPH on the GPS, the bikes are showing between 61 and 62. With a 90/90-19, they were all right close to 65 MPH.

What size tire do you have now, that you are going "up to a 110"?
If you plug in the numbers, the 110/90-18 is only about 1.6% bigger than the 90/90-19.
Using the stock 90/90-19 as the baseline (with a very innaccurate speedo):
100/90-19 gives you 2.8% correction.
110/90-19 gives you 5.6% correction.
110/90-18 gives you 1.6% correction.

Please also remember that the 110 width tire needs a wheel that is wider than most of the GS wheels, which are 1.85" wide.

.

 

[salty_monk]

You should run the 2.15 wide rim from the front of the 82 650 or 850 if you want to run a 110...

 

[Steve]

You should run the 2.15 wide rim from the front of the 82 650 or 850 if you want to run a 110...

It might have been all the shafties that had the 2.15.

I got mine from an '82 1100G.

.

 

[Chuck78]

Or I could run THIS front WM4x18 (2.50" wide) DID rim on the front! Avon specifies a 2.50" as being the ideal rim width to accept a 110/90. I would have preferred a 110/80 but speedo would read very high, and there's not much worthwhile available in a 19" beyond a 90/90-19 (or similar original 3.25x19) and a 100-90-19. I suppose knowing this speedo accuracy info via your GPS calculations, a 100/90-19 on a 2.15x19 alloy rim would have sufficed. I will keep that in mind if I go to build a big bore GS425 or GS400 racer (minus the cafe seat and rear frame chop) up to 450 or maybe 516cc's.

 

[Chuck78]

I still have not heard back from FromThePast about the fork brace fitment, but I'm fairly certain any of those that I listed will fit, but will steer clear of the GS650 brace that says the model was fitted with 37mm fork tubes, just to avoid any problems.

Got my Mike's XS cartridge emulators in the mail just a few minutes ago, gaskets are in at the local shop for my carbs, cycleo-rings.com kit arrived Monday, making custom twinpot bracket mods for the upgrade, spokes for the front wheel on order, saving up for some nice tires... Lots of good news these days! Asking for the fork brace and a set of Hagon 2810 shocks for my birthday, which is the last day of our West Virginia/Virginia mountain riding trip, so hopefully I get both at the beginning! 530 chain conversion to install my GS1100E swingarm is also on the list, but noted lesser priority

 

[Chuck78]

Well, I got the 0040 and it does fit the fork legs as I suspected it would! The only thing that I noticed is the picture and description shows that it has the arched center and the one in the 0040 box that I got does not have the arched/ clearanced center. Have not installed the fork legs on my bike yet to know if it will be any issue with my fender or near stock tire diameter. By the end of the week I hope to have the front end swapped out and my carbs rebuilt and new wheels installed! Twin pot brake setup with custom brackets and rotor spacers, GS650 dual disc forks with cartridge emulators and chopped Springs. Just got the wider Alloy rims built up with wider Shinko tires mounted this afternoon!
leaving for a West Virginia Road trip in about 10 days so lots of goals before then, mostly all mechanical goals. GS1100E swing arm swap & some somewhat custom gauges and some cosmetic goals by AMA vintage motorcycle days in July at Mid Ohio Sports Car Course!

 

[Charlie G]

Chuck,

I just put emulators in my 650 forks and I was wondering if you used the stock 650 springs and if so, which spring you cut and how much?

cg

 

[Chuck78]

Funny you should ask! I actually used the longer of the two springs in the 750 Forks To get about 46 pounds per inch I believe it was. Just 10 minutes ago I went over with my friend how to chop 11 coils out of my 650 springs to get about 48lbs/ft with 6.8" of available travel. Those Forks have a shorter progressive spring and a longer spring with wider spacing. Chop no more than 11 coils if u plan to run up to 1" of preload.

See my thread on hagon 2810 rear shock spring rates for detailed info on the spring chop calculations for these '81(?) Gs650g forks

 

[Chuck78]

I should clarify that I abandoned the 4 inch long tightly wound spring and used only the longer GS 650 Springs, Minus 10 or 11 coils sitting here on my workbench that he chopped out earlier. His 1977 kz1000 springs were a little off compared to the Suzuki's. They used very tightly wound Springs with 66 coils & Thicker wire with very little spacer. They were sitting around 38 or 39 lbs-inch but after figuring up the free space available for compression you could only cut about 1 inch out of them. By chopping a substantial length from the 650 Springs which have a much wider coil spacing, we were able to get about 48 lbs-inch. The KZ 1000 has 36 mm fork tubes with .5mm greater wall thickness than my bikes, and coincidentally uses the same diameter Springs. This is probably a great news for him because his forks are stiffer and he can use the mikes xs $55 cartridge emulators most likely

 

[Chuck78]

My buddy came back with an ear to ear grin after doing the 650 spring chop install on his kz1000, set it handled substantially better and he had much more confidence with that and a good Shinko front tire that we just installed as well as some stiffer rear springs on some old unknown shocks

 

[Guest]

Bringing this back from the dead. Did the 24-0040 brace work out alright? I have a '83 GS650G where I won't be running a fender, and just wanted to make sure the brace will clear the tire (looking at my bike they all should). But I'd like it to have a little bit of an arch for aesthetic purposes.

Thanks for the great info in this thread btw!

 

[Chuck78]

The one I got fit GREAT! Its cast aluminum, there is a higher end company that makes them cnc'd for $150-ish, the name slips my mind.

 

[Guest]

The one I got fit GREAT! Its cast aluminum, there is a higher end company that makes them cnc'd for $150-ish, the name slips my mind.

Perfect, thanks! Do you have any pictures of it mounted from straight on?

 

[Guest]

Perfect, thanks! Do you have any pictures of it mounted from straight on?

Oh geez, never mind. Here I thought when you said there was no arch, the entire brace was straight across. Now I see that it's the connecting piece that either has the arch or doesn't.

Thanks again!