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Hi Chuck, I'm glad I was able to help!AWESOME, THANKS JOHN!
I suspected this was the case going off of the triple that I had here with the same looking stem. And it did look like there was quite a bit of room to space the triple up and down on the bearings and head tube of the frame. This is most excellent news. I was going to buy one of these myself just to measure it, as I see some on eBay for $13 just for the lower. I suspected this was the case going off of the GSXR & Hayabusa triples that I had here with the what appeared to be the same stem. And it did look like there was quite a bit of room to take the triple up and down on the bearings and head to above the frame. This is most excellent news. I was going to buy one of these myself just to measure it, as I see some on eBay for $13 just for the lower.
This triple sounds like it will be the ticket then for getting quicker steering on Fork conversions without much hassle.
Running a GS with a 17" set of wheels and this triple, in CBR 600 F4 or F4i forks, Bandit 1200 Forks, 1989 GSXR 1100 K Forks, or for the smaller bikes with shorter forks, 1989 GSXR 750 forks, and I believe 1990 is the same on the 750. RF900R forks are the same as Bandit except the 1997 models, the last year, had adjustable damping, but they are very short, even shorter than the CBR 600 F4 forks, which are about the minimum Fork blank that you would want to run on the bigger bikes, and that will drop a front a good bit even. The RF forks would work great on a twin but the springs are a bit stiff for a lightweight twin, but may work well for a GS 550 or 650 with a 4 into 2 exhaust.
This is most excellent news because this gives bikes a reduction in trail to make it much more sporty feeling than the stock specs! I was befuddled quite often with people who would run a near stock frame rake with 17 inch wheels and very minimal offset triple from their modern fork swap, as it would not improve on the steering whatsoever, and kill the ground clearance.
Thanks a lot, John!
FYI AllBalls has 5 mm lower bearing spacers that they have shipped me with kits before, so this is very readily available in very doable.
Chuck, you will find in attachment the spindle adapter required to fit a 15 mm spindle in a GSXR/Bandit front fork.John, did you have any drawings that you had posted previously for those 15 mm to 20 mm axle adapters?
Did you ever figure out why the first GSXR 1100 K Fork was so stiff? You said you swap the fork tubes. I wasn't sure if you just meant the Chrome upper tubes, or the entire fork leg assemblies. You also mentioned some different oil viscosities. Have you just put too stiff of oil into it? 2.5 weight was best? In Bel-Ray?
How did the GSXR 1100 K Forks compared to the Bandit damping?
Those two forks get the vote for me because they look almost exactly like a GS Fork, whereas they very awesome performing CBR 600 F4 Fork has the modern style caliper mounts with the lower projecting rearward an inch-and-a-half further. This is probably not a big deal at all, but I like the fact that the first two that I mentioned look very much like a GS Fork.
Thanks!
Chuck
It was a long time ago and I believe that minute changes were made while discussing with the machinist.Thanks John, I emailed you from my Yahoo address.
And then afterwards, I looked at the rest of this thread and saw that you posted a photo of your sketch! Is that what you gave the Machinist?

Revisiting this for some of my upcoming project bikes...
I now have a round column Vertical Mill, Enco 29, similar to the RF 30 and RF31 newer models, & a rotary turntable, adjustable boring head, etc for it...
I am looking at buying some 4 or 4.5" x 2.5" thick 6061 T651 aluminum bar stock & custom milling my own offset upper triple to make some of these shorter modern forks come back up to stock GS ride height by dropping the upper clamping portions of the fork tubes about 35mm offset lower.
this would allow me to run the GSXR 1100 K 1989 forks at stock ride height. it turns out that the comparison measurements for our bikes are a bit skewed because the GS upper triples already offset down a little bit, and are approximately 3/4" advantage increasing in ride height over a flat upper triple.
so just measuring the fork length from the center of axle to the top of the chrome tubes is not enough, you also need to take into consideration the steering stem length, upper triple placement, and any offset to drop the outside of the upper triple lower than the center of it...
This places a bit more stringent criteria on fork heights.
so my only serious motorcycle twisty road week long road mountains trip of the year, I was scraping left and right when fully loaded with camping gear and going through really tight twisties for a week. A little bit stiffer fork springs would help, but I already have longer rear shocks...
So now I have become very adamant about running the proper ride height on the front of a GS 750, GS1000, GS 1100, or the bigger shaft drive bikes as well if you are into those.
I will say that I think the VTR1000F with either the PC800 triples, or if the 90s and 2000 CB750 nighthawk triples or the 84 Honda VFR interceptor triples would work (steering stem height for bearing spacing is unknown) those might be the best ticket for adjustable (rebound) damping. The Bandit 1200 forks are still at the top of the list, especially considering you can run the V-Strom triples. Taller rear shocks and an 18 inch front wheel would make that set up work very ideally.
I never really looked into the suggestion of the 97-07 YZF600R Thundercat forks, but it seems that any modern sport bike that is designed to run clip-on bars on top of the triple clamps, they are going to be the taller forks that we would need. When searching for conventional forks. Or inverted forks I suppose as well.
Those YZF600R forks are 41mm, so I dont have a definite recommendation on triples other than the rare GS1100GK triples (50mm standard GS offset) or Honda PC800 triples (55mm offset, only for taller tires like stock 19" or 110/90-18), or possibly investigating 90's-2000's CB750 Nighthawk triples for steering stem height compatibility.
The great thing about them is the height, and that they have fully adjustable compression and rebound and preload, all externally! That bike is a bit lighter though (412lbs dry, 463lbs wet), so they will be a bit soft for a heavier GS and a very expensive set of fork springs would be needed, or else chop those stock fork springs slightly. They are 0.81 kg/mm. For a GS550 or 650, these would be pretty incredible as is with the right triples (GS1100GK!).
The 99-07 versions are listed separately by Racetech, although 97-98 are pretty similar. The first 2 years (95-96) are drastically different and do not look appropriate for a vintage bike

My personal conclusion for GS 1000 and GS 1100 Katana is to use a first gen R6 RSU fork for the GS and Bandit 1200 stanchions with DL 1000 triples for the Katana.
Here's a pictures of the GS 1000 so equipped.
The GSXR 1100 engine further helps for ground clearance of course...
View attachment 59676
I believe I have the early Vstrom triples with removable handlebar fittings.
The bearing areas are both 30 mm in diameter as you stated however the bottom is slightly larger requiring a force fitting.
The bottom landing is 22.5 mm long while the top is 16 mm long.
The inner distance between the two landings is 151 mm.
Here's a picture:
View attachment 56368

John Kat
Revisiting this thread again, I think I might have solved two problems simultaneously!
John Kat If you have a chance to measure the press fit area all the way to the very bottom of the steering stem on that V-Strom stem, that would be appreciated. I may just buy a set of triples off of eBay since you have already successfully used them I believe with a lower bearing spacer or a stem swap, I'm pretty certain that this will solve my issue. I may have to recess it up into the Suzuki RM 125 lower triple a little bit more, but It would require the least amount of machine work of all...
Thank you for posting!