Hi guys! Has anyone done a gsx400r front end swap on their GS? I can get a complete frontend for cheap, but if it is not worth it, then I am not going to bother.
If I were you I wouldn't waste time swapping the front end over..............I would swap the whole bike :laugh:
That would be defeating the purpose of building the GS cafe racer! :laugh: But I can only get the front end in any case. I have decided to go for it and figure it out along the way.
Look at the online parts fiches and check out the headstock bearing sizes, always a good place to start.
According to allballs racings website, bearings and headstocks seem to be the same, so I might be in luck. Picking up the frontend on Thursday, cant wait.
I guess I don't understand why it would be worth it.
... either a) to use a GSX400 fork, b) to try and turn a GS500 into a "cafe racer", or c) why a "cafe racer" needs an upgraded fork?
is there any performance improvement in the GSX400R fork over a GS500 fork? is this improvement even possible to discern on a street driven GS500? if not, then are you really going to take a "cafe racer" to an actual race track for track day events or to race?
A stock GS500 fork with the correct springs and oil for the weight of the rider and intended use, along with a matching rear shock, should be more than enough to optimize performance on public roads.
I am sure I am missing something here, like a lot of something. I'm the guy who tried to turn a GS500 into an adventure bike, so I understand turning what you have into something more like what you want but if you don't have sentimental reasons to keep a this specific GS500 then swapping it for a GS450 or just about any UJM will give you a much better "cafe racer" platform.
I have seen folks swap GS500 forks for others for a number of reasons, most often it was a technical challenge they just wanted to try, sometimes they had the parts laying around and wanted to see what they could come up with, etc. Tinkerers at heart. But those folks don't tend to ask these kinds of questions.
To answer some of your questions:
- I bought a semi-finished (All be it a bit crappy) GS400e cafe racer off someone for cheap as a project, thus it only makes sense to continue with the cafe theme
- The stock GS400 forks are pretty crappy, not adjustable, and are in pretty bad shape rust wise. Rebuilding them costs way more than what the complete front end will cost.
- The front end comes with the brakes off the GSX400 = twin-rotor, way more stopping power, as the motor is currently receiving some performance mods it will just make me feel a bit safer on the roads although it will still not be a rocket, I still like to know I have enough to stop it.
- I will indeed be doing track days as I stay pretty close to one
- Aesthetically it just looks way cooler in my opinion
I have built and raced quite a few 2-stroke bikes in the past, mostly MX and one TZR road bike (and then I got married), so the world of the GS and four strokes are new to me. The cafe racer will be my daily transport to my workshop and back, as well as a bit of marketing, so it needs to tick all the boxes as far as looks go.
I get it. I am not sure about your performance mods on the engine, and I'm not sure you have a "GS400e" ... I don't even know what that is. But I also don't think the replacement fork will be an upgrade and I'll be surprised if it can be swapped and cost less than a replacement set of GS500 fork legs to remedy rust etc., even if you add in the cost of a new set of springs and a cartridge emulator setup. And cheap ebay top caps for preload adjustment if you just HAVE to have adjustability.
The dual front rotors is going to require a different master cylinder, two calipers, a whole different front wheel along with rotors, etc. I recently replaced the broken fork legs on my Bonneville with Thruxton parts which bolted straight into the triples but required a 10mm different rotor, a custom machined part to adapt the rotor, and more custom fab parts to get the fender to mount correctly. It was a major chore, and that was a very slight change.
If you just want to do it, then just do it. But it's going to be a whole lot more work and expense than you think and you are not likely to get a single bit of measurable benefit. Likewise your engine mods are not likely to yield any performance improvement. With a rejet and maybe a slip on muffler, you are going to essentially optimize the GS500 engine with stock parts and tune. To add actual usable power is going to require major surgery that would be far easier to do by swapping a whole different engine, and then why? Why not take the entire bike instead?
I mean, frankly, I don't usually like to agree with Sledge, but I do in this case.
There has been at least 3 versions of a GS400E that i can think of, one each from the 70s 80s and 90s.
The last one looked identical to a 500E but had a strap across the seat but I believe it was only available in Japan.
Mr72 doesn't always agree with simply because he doesn't know as much as me :dunno_black:
It is a 1991 GS400e, was not available for a long time before they replaced it with the GS500E. As far as the rest goes, I got a complete front end of the GSX400R, wheel, rotors, triples, switches, clip ons,master cylender etc. All but the rest of the bike that is usually connected to the frame, for the South African equivalent of $250, so not too bad in my opinion. Taste differs I suppose, as does opinion, there are loads of guys that have done fork swaps on the forum, so I figure why not try it, even if it is just for looks. Hell, all the pro builders out there doing swaps on Cafe builds must have some reason for doing it.
As for performance, again, not looking to build a rocket, otherwise I would have just bought a proper super bike, or better yet, put a big bore 2 stroke into the frame, but getting things done like a port and polish, some minor work on the cams and getting the carbs properly sorted will no doubt improve the stock performance.
What the heck, go for the swap... Trying things and making it your way is true custom... not just what someone else does.
I looked up the GS400E and found the specs on the 91. It looks just about the identical bike to the 500. Pity the stroke is shorter on the 400, otherwise an easy cylinder block and piston swap would net a nice improvement in power.
Quote from: Sporty on January 13, 2021, 05:05:57 PM
What the heck, go for the swap... Trying things and making it your way is true custom... not just what someone else does.
I looked up the GS400E and found the specs on the 91. It looks just about the identical bike to the 500. Pity the stroke is shorter on the 400, otherwise an easy cylinder block and piston swap would net a nice improvement in power.
It is a pity, its one of the first options I looked at.
Just got back to my workshop with the new front end, I suspect I might not get much work fone this afternoon, you know, priorities and such, the bike takes preference over all else :D
So I have the front end test fitted, bearings are the same, stem is slightly longer, so I will have to machine some spacers, but I think it makes a huge difference looks-wise over the stock front end. Once I have fitted it for the final time I will do a write up for anyone wanting to do the same conversion.
GSX means 4 valve per cyl, I forget what the r means, 4 cyl ?? No Katana's had F but are 4 cyl.
Anyway Is the GSX400r a 4 cyl water cooled ??? What year ? Looks like its part of the GSXR genre from the forks. Bandit 400 was an F wasn't it ? GSX400F in 91 ? Which had the same 39mm fork as the GS but disk on the other side.
A fork leg swap and you have twin disk 320mm rotors (the biggest ever freaking rotors you can fit on that wheel)
Cool.
Buddha.
I do like the look of the beefier upside down forks on the GS.
Going by the photos those GSX forks look a bit shorter than the stock ones. Have you measured the difference?
Quote from: The Buddha on January 14, 2021, 04:53:24 PM
GSX means 4 valve per cyl, I forget what the r means, 4 cyl ?? No Katana's had F but are 4 cyl.
Anyway Is the GSX400r a 4 cyl water cooled ??? What year ? Looks like its part of the GSXR genre from the forks. Bandit 400 was an F wasn't it ? GSX400F in 91 ? Which had the same 39mm fork as the GS but disk on the other side.
A fork leg swap and you have twin disk 320mm rotors (the biggest ever freaking rotors you can fit on that wheel)
Cool.
Buddha.
These are off a late 90's GSX400R, the SP2 model. It is basically like a smaller version of the slingshot, watercooled, 4 cylinder. I am not sure which countries recieved them, in SA we do have a few around, but they are all grey imports.
Quote from: moe_tunes on January 14, 2021, 05:29:21 PM
I do like the look of the beefier upside down forks on the GS.
Going by the photos those GSX forks look a bit shorter than the stock ones. Have you measured the difference?
They are only slightly shorter, but not enough to adversely impact handling, it looks way more due to the fact that the bottom neck bearing is not in at the moment, so the rake angle is not correct. Got some spacers made up this morning, so I am going to try to get it fitted properly this afternoon.
Quote from: The Buddha on January 14, 2021, 04:53:24 PM
GSX means 4 valve per cyl, I forget what the r means, 4 cyl ?? No Katana's had F but are 4 cyl.
Anyway Is the GSX400r a 4 cyl water cooled ??? What year ? Looks like its part of the GSXR genre from the forks. Bandit 400 was an F wasn't it ? GSX400F in 91 ? Which had the same 39mm fork as the GS but disk on the other side.
A fork leg swap and you have twin disk 320mm rotors (the biggest ever freaking rotors you can fit on that wheel)
Cool.
Buddha.
This is the SP2 model
Holee effing hell. Well we received in the US an 92 only 600 version of that same thing. Heavy as the dickens for a 600, almost in katana 600 territory but had a lot of good stuff on it. Good forks, wheels, pretty much the 91 GSXR 750 which was considered by many as the best of the 750's till 96. I like those twin cradle frame ones but prefer air oil cooled.
Cool.
Buddha.
So you never got the slabsides in the 80s?
Look at the frame and swinger, I am convinced they were the inspiration for the GS5s
(https://i.ebayimg.com/images/i/191564903583-0-1/s-l1000.jpg)
Oh yea first gen GSXR's were slabsides. 85-87 750, 86-88 1100. But never had upside downs forks on those.
In fact 90 1100 still ahd the right side up forks. IIRC 90 750 and 91 1100 were first years of upside down forks.
I have a 90 1100. Not a slabside and no USD forks. 1127 long stroke motor and threaded valve adjusters.
But it had eyelet on top and clevice on the bottom rear shock.
Cool.
Buddha.
Quote from: The Buddha on January 22, 2021, 09:54:18 AM
Holee effing hell. Well we received in the US an 92 only 600 version of that same thing. Heavy as the dickens for a 600, almost in katana 600 territory but had a lot of good stuff on it. Good forks, wheels, pretty much the 91 GSXR 750 which was considered by many as the best of the 750's till 96. I like those twin cradle frame ones but prefer air oil cooled.
Cool.
Buddha.
I have actually had the chance of riding one of the little 400's. They are amazing little bikes, and they perform quite close to the 600's.
What was the last year of the 750 air oil cooled. 89 ? or 90 ? One of those was super short stroke with longest connecting rods of all of them. That was lightning quick, and in many cases outran the 1052 both on paper and the real world. The 1127 theoretically out performed it on paper but 1127's were torquey in the mid range but ran out of revs @ 11K, that one short stroke 750 revved to 13.5K.
The only 400 4 cyl to ever appear stateside was the 92 Bandit 400. As we all know the GS was responsible for it going nowhere, and I'm guessing the Honda CB1 and the MZ 660. MZ kept at it past 2005 in fact mainly due to the fact they were never put in the same space as the GS. All the foo foo euro ones stuck together, and compared to an Enfield Bullet, and a porky and $$$ Guzzi, MZ sure looked cheap. They were damn fine bikes IMHO. Like a GS with every part upgraded.
Cool.
Buddha.