Suzuki GSX400 Four Cafe racer with USD fork and monoshock


New Member
according to modern tire convention, your stock tire already has way too much sidewall. This causes tire flex and hurts stability and feeling. that's one of the main reasons for going to a wider wheel. I would also look into getting smaller diameter rims if youre gonna lace them up to the old hubs. apparently all the best rubber comes in 17" these days.


Suzuki FTW
I already know that, because I studied suspension, chassis and handling and such last year when I was in a student team. I developed the entire rolling chassis of our electric racing motorcycle. But based on looks I would like to stick with a this wheel, second reason is money. I am a student after all. But maybe upgrading to complete custom laced rim is a good one for next year.

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Suzuki FTW
Wow it's getting dusty here, time for an update!

First of all, al small milestone. She's back on her own wheels! I've put some tyres on the rims to make it easier to move her around.

Because I wasn't happy with the look of the tank and the seat I've had the tank modified and extended the subframe by 3 cm.


Some outdoor pics:


Next step was a trying to get the shape for the seat that I have in my head onto the foam, I finally manage to get it how I want it to be. (Looks better in reallife than on the picture because of the light)


Next weekend I will start with fabricating the seatpan, bracket for the headlight and a bracket for the taillight.


Been Around the Block
Looks great! But it looks like a tight fit to get the exhaust system on without risk of having the front wheel hitting it. Is it the pictures or is the plan to extend the front fork by making a "dropped" upper triple tree?

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New Member
this bike looks amazing. I'm softening up to the stock wheels, but how are you gonna mount the twin disks on that front? or just run one disk?


Suzuki FTW
Thanks guys!

@Eleganten: It's gonna be like this, I already saw that it's gonna be quite close but I think it's enough.

@Hellapet, I was suprised as well how good it looked with stock wheel sizes. The front wheel is from a Suz gs550 so twin disks standard, so on both sides I'll have a spacer:



Active Member
That's a nice bike :) I am currently building a gsx400 2 cylinder and I find the Suzuki tank a big no-go. I will be switching to gs550 gas tank.

Wysłane z tostera


Suzuki FTW
Thanks! Any pics of your build? I still have a gs550 tank laying around as well, but I found that one way to big for the style for I have in mind. But the gsx tank also looks different on the smaller 2 cylinder version.


Suzuki FTW
Progress of last Saturday:

The plan was to make a seatpan, so that's done. :D


Used some welding nuts for easy alignment.
I guess they will stay in place :p :


The plan is to mount the regulator/rectifier and ignitor underneath the seatpan. Combined with a mounting point for the taillight bracket.

I also started with the bracket for the indicators and taillight. I like the indicators but not sure if they are the right size for the narrow bike. But I can easily swap them for smaller ones.



Also cleaned up the garage, my parents were getting annoyed by the mess. ;D
Immediately gave me the opportunity to make a useful thing for the electrical wires.




Over 10,000 Posts
Neat project. That short wheelbase should be good for some interesting handling. When you checked for exhaust clearance, did you bottom the forks out first? Don't mean to beat a dead horse but it does look really close.


Suzuki FTW
Maritime said:
Just found this now, nice work so far!

Thanks, the topic hasn't been on here for that long ;)

VonYinzer said:
Neat project. That short wheelbase should be good for some interesting handling. When you checked for exhaust clearance, did you bottom the forks out first? Don't mean to beat a dead horse but it does look really close.

Thanks! I get your point and I still need to check it because I haven't at all. I was already planning to check it with the forks bottomed out. Otherwise I can always modify the middle two exhaust pipes a bit to not stick out any further than the frame. Because bottoming out and full steering lock probably isn't going to happen. :)


Suzuki FTW
Christmas holidays for me, so time to work on the bike! ;D

The first thing on my list was to finish the front brakes. Measured everything twice and put the discs on the milling machine to mill some new holes for the GS550 hub bolt pattern. Luckily everything lined up perfectly:

The calipers also slide onto the discs perfectly like they used to on the Kawa originally :)



As already mentioned the clearance between tyre and exhaust would be non existent.

First a pic with exhaust on and fork in normal position:


And here's one with nearly fully bottomed out:


Tyre is hitting the exhaust indeed. But like I mentioned earlier there is a lot of space behind the exhaust so they can move back a couple of centimeters, giving me enough clearance. Unfortunately this exhaust is shot. It's rusted trough at the flanges and not worth fixing. So I decided to go with a full custom stainless set up that will be build in a couple of months (I first need to gather some money :-[)

Something else I did was aligning the real wheel and the sprockets. Unfortunately it looks like I don't have the matching drumbrake that belongs to my rear wheel.


I'm suspecting that the one (drum brake) I have now is from a CB550K3 from 1979 and that my rear wheel actually is from a CB550F2, could somebody confirm this? Are there any other drum brakes that fit this rear wheel? Because I havent managed to souce a drum brake from a CB550F2 yet.


Suzuki FTW
First of all, happy new year to all of you! (I think it's still allowed within 10 days right? ;))

Thanks to the great help from an eBay seller I managed to find the fitting drum brake.
The one I had is from a Honda CB550K0-K2, but my rear wheel is from a K3 model. The drums are slightly different.

Look a lot better:

But the rear bushing in the lathe to compensate the slightly bigger offset on the new drum brake. Now everything fits nicely and is properly aligned.

Some new stuff I got:

- Cheap air filters, will put K&N on in the end but for now these will work. (They just fit)


- Muffler:

- M10x1.25 12.9 bolt for the front calipers. Of course immediately mounted them:

Also started on the new wiring loom. Using some of the old connectors on the R/R, signal generator and CDI. Rest of is all going to be changed.


Hopefully this afternoon I will get my new handlebar switches and throttle lever. They're from a Suzuki GSXR600 K4.

Next update will be when I finished the wiring loom and the welding on some of the brackets I still have to do.


Suzuki FTW
It has been a while, time for a small update.

Mostly busy with exams, but last one coming up on Friday. After that I have a week off, so right now ordering some stuff to keep me busy next week. ;D

Some pics of the nearly finished wiring loom, I forgot to post them on the previous one. ;)

Handlebar switches of a '04 GSX-R 600, I've put a new honda 2.8mm connector on in because I had them laying around for the speedo anyway. It's nice to keep everything uniform.


Bunch of wires:



Two more relays or on the way together with a led for the oil pressure. Right now I have the parking lights switching on when I turn the key. I'm going to use the relay to switch on the low beam when the kill switch is in the 'on' position, but I want to switch it off when I press the starter button. So, that is why I am using two relays.

Thing that came in already:
- New throttle cable for the GSX-R throttle
- New clutch cable
- brake fluid and copper rings

And also the battery came in, only 500gram instead of the original 3,5kg. But the decision is mostly based on size. It's small so I can fit it underneath the tank.


These mirrors are on the way:


Andddddd I saved the best for last. A new upper tripple clamp. Own design and CNC milled by a guy a now from 7075 aluminium. When for a clean look. I think it's mission accomplished. ;D ;D



Till the next one!


Suzuki FTW
And the wiring loom is done! (except for some small bits like, rear brakelight switch, signal wire for rpm and the lighting for the license plate)

Before tiding up:




And after:


Everything fits neatly underneath the tank and most importantly everything is working as it should.

The proof:

She easily fires up in one push of a button. I think the new more powerful battery also helps a lot. :D


When I bought the bike, the clutch was really heavy. I decided to change plates, springs and cable. Not the desired effect. Still far too heavy, until today when I noticed that the springs I replaced the old ones with were a lot stronger. Luckily I don't trow away stuff easily so I still had the old ones laying around. Replaced the new ones with the old ones and now it is like it should be! ;D

Also a new clutchlever is on it's way. Of a GSX-R 600 to match the handlebar switches and the throttle:


There was something strange today when I fired her up. I heard there were only 3 cylinders firing and when I checked the exhaust only the ones on 1, 2 and 3 were starting to warm up. My guess is either the spark plug is fooling me, the ignition cable is dying or that the complete coil is dying? ???

Some more good new to end with. The foam for the seat mold came in so hopefully I can start with modeling that on friday and see if there is some time left to make brackets for the headlight and the taillight.

It's 9pm over here in Holland so I wish you guys a great evening!


Active Member
Trippe trees clamp looks great :) You might have some issues with those cheap pods. A friend of mine who builds bikes for a living told me to use some interfacing folded in half to smooth out the air flow. Of course, you might be one of those 1 in 20 people who put the pods on and the bike runs like a charm ;D


Suzuki FTW
Thanks! About the pods I know they're on the bike to have an indication of looks and size. I don't care if these get damaged. Later on I will spend some money on proper K&N's :)

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See Bee Five Fifty
Really cool project. The suspension geometry up front looks like its going to probably be a hairball to steer.. ???

Another thing to watch (im dealing with it on my build) is the chain clearance at the swingarm


keep up the good work


Suzuki FTW
Thanks Dude, I still the handling will be fine. Still have to check it all, but I might have some options just in case.

Probably need a weaker spring anyway. But I know that the chain clears the swingarm, will put a small piece of POM (the white plastic stuff) as a chain guide just in case. Thanks for the advice!

More sad news, the oil plug is leaking. Going to look for a secondhand sump. If I can't find a proper one I need to put a helicoil in. :(

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