Topic: 2003 Yamaha R6 fork on CB550

[Franky]

Hi guys.

My CB550 K3 has always had a #$%*ty front brake. I've replaced parts, restored,  cleaned and what not, but it didn't really do the job. I guess I'm either an idiot or something is just plain old worn out. My CB360T seem to have the exact same brake, and it's fine.

Well, instead of spending loads of time and $$$ on the stock system, I figured I'd spend  loads of time and $$$ on a more modern set-up. Also, the 360 is my stock bike, whereas the 550 is the wrenching-project-screw-up bike ;-)

Greatly inspired by the awesome FunJimmy build (http://forums.sohc4.net/index.php?topic=27159.0), I started looking for parts. Since Denmark has very heavy taxes on motorcycles, I ended up finding stuff on especially german eBay and eBay.com. I ended up getting a great deal on a 03 Yamaha R6 fork, which isn't that much different than the 99-02 version used by FunJimmy. His thread goes into quite some detail, but for someone who's skills are so-so, it can be a bit hard to follow suit. For instance: the spacers and hub he made/machined doesn't have any dimensions.

With this I aim to make a fork-swap-for-dummies thread :-)  I know I would have loved one, so I hope you will too...

[Elan]

nice, theres a few of us doing similar things, im currently doing an 04' gsxr1000 onto my 750. lots of pics!

[Franky]

To fit the R6 fork you can reuse the stock bottom bearing, but you'll need a funky top one. The website of All Balls Racing has an amazing feature (https://www.allballsracing.com/index.php/forkconversion), that lets you choose your motorcycle after which you'll be handed a list of compatible forks AND the bearings you'll need to make it fit. (Do read the warning though!)



The stem-length is just about perfect. And after getting the All Balls Racing bearing, everything just bolts right on.



Everything is nice and tight. The rubber rings are from both the stock Honda and R6 fork. It's seals somewhat, but I plan to machine a small cover for extra protection.



You'll have to get your hands on some R6 (99-02 and 03) calipers and 95-98 Honda CBR600 F3 rotors. (The rotors were also used on other Hondas of the time).



I've started machining the hub to make room for the spacers. However, the machine I have access too is rather small and may not be accurate enough.

After carefull measuring of the mounted R6 fork, the calipers, the CBR rotors and the stock hub, I have made some detailed drawings of the spacers on my computer. This should allow me to fabricate the spacers without too much trial and error ;-) Wish me luck!

[Franky]

Elan! The cool stuff you're doing is making my project look like kid's play :-)

Also 'my project' is off course FunJimmy's - all credit goes to him.

[Franky]

The drawings are pretty much complete! And even better: On monday I'm going to meet a friend of a friend who works at a topnotch machine shop. Hopefully he'll have time to help out soon :-)

Below are some jpeg images of the drawings and here's a link to a scaleable PDF file  http://www.franky.dk/Honda/franky_fork-spacer-drawings.pdf . (Once I actually get the spacers and all done, I'll update both with whatever may change).


Overall drawing


Left Spacer


Right spacer


Hub

[RAFster122s]

Franky,

Thanks for documenting and sharing the photos.  You do realize that the bike's braking performance with one modern caliper with sintered pads would be light years "figuratively speaking" ahead of the stock braking system.
I think FunJimmy felt it sufficient.
In my view you are just adding un-needed weight and expense for cosmetic appeal and braking that will easily exceed your tire performance.

Good luck with the project.

Any idea what kind of time you will have invested in machining the hub?

Are you staying with stock 19" front wheel?
David

[Franky]

Yes, I know that one disc is more than adequate.

 I'm including the nr. 2 mount so that myself and others have the option of adding that extra disc. Although the caferacer craze used to be all about stripping weight and increasing performance, today it's just as much about looking cool. I'm not even sure what I'll end up doing.

Machining the hub is the easiest part and I'll report back when I have more details and experience.

For now I'm sticking with stock rims, but if you know of any good deals on allly rims, i'd love to hear about it.

[cwchan]

Many SOHC'ers are on Do the Ton as well.  Check out what this guy has done so far

http://www.dotheton.com/forum/index.php?topic=43369.130

[Retro Rocket]

Yes, I know that one disc is more than adequate.

I don't think it is an issue at all, 1 modern disc is better than stock, granted,  but these bikes are relatively heavy and there are lots of modern bikes that are lighter than ours with twin discs. I have uprated twin discs going on all 3 of my 750's..   Looks great...

[Franky]

So finally some progress on this project!

I had the hubs and spacers to mount the discs made by an awesome machinist, got new spokes form David Silver and was finally ready to start assembling. The below pics and words are summed up from quite a number of days/nights of wrenching. Amazingly enough, all my calculations, measuremts and drawings have been pretty much perfect! This surprises me quite a bit, as I'm usually too impatient, get carried away and/or not being thorough enough. Only one uncomplicated axle spacer and caliper measurement was a bit off - easy to correct.


Ingredients for a great night: New parts and fuel for the body!


Nice work! I had my machinist press the bearings into place.


Finding those long bolts was somewhat of a hassle.


Everything seem to fit properly.


The clearance to the fork leg is 4 mm (measured from the rivets that protude a bit from the disc surface).


After a few... erh... practice runs, I got the lacing right.

In order to center the wheel on the axle, more spacers is needed. After careful measurements I made some drawings. The spacers are quite simple, and I should be able to make them myself. But, my new best friend - my machinist - is doing such a good job and at great prices too, that I ended up having him do them. I did mess up one measurement, so I had to shave off about 10 mm from the middle spacer. (Drawings are updated). The axle spacers drawings you'll find here:  http://www.franky.dk/Honda/franky_cb550_fork_axle-spacers.pdf and below. The two outer ones are stainless steel and the middle one brass. You could use any material - the machinist and I just used whatever I had lying around.



Note the different alternate versions.


Shaving off 10mm because of brainfart when doing/calculating measurements. Drawings are updated.


The spacer rests on the inner bearing ring and the fork.


Finally all mounted. Man those discs look big!




More info coming, but it's getting way to late and junior get's up at 05:30 in the mornings... yay!



------------------------- !! UPDATE  august 2017 !!  --------------------------
A few guys have asked about the resulting height of the forks - here it is:


75 cm from the center of the front axle to the top of the triple tree.


Approximately 97,5 cm from the ground to the top of the triple tree.

[Elan]

looking good!

[Glaede]

Nice! Looks really good.. I'm also experiencing a very weak front brake even though I overhauled the front caliper, new brake pads, mastercylinder and stainless lines, so I'm considering a dual disc conversion.

Btw, fedt at se en dansker herinde! :-) Jeg er selv ved at bygge en CB500 cafe racer - har lige fået den synet og er ved at bygge mit sæde. Mangler dog at få motoren til at spille 100%. Hvad er dit forgaffel projekt rendt op i og har du benyttet std. fælg og hjulnav?

[RAFster122s]

Did you switch to an FZ6 top triple tree? Looks like it from the pic with handlebars (superbike?) In you last set of photos. Nice of Yamaha to use conventional fork R6 design spacing and forks on the FZ6.

[SOHC4 Cafe Racer Fan]

Kick-ass machining work. The adapters look great. Too bad you don't get to see how clean they look.

[Viktor.J]

LOOKING GOOD ! Sweet as hell, keep up the good work !

[Franky]

@RAFster122S: It's the standard top triple tree that came with the fork. I just drilled some holes and used two sets of CB550 handlebar-clamps to hold the superbike handlebars. It seems strong enough, maybe I'll have to reinforce it in some way...? And yes, I actually like the mash-up of 70'ties style and new high-tech look, but in this case I like to keep it more old-school, so the conventional fork design is perfect. I have a friend who has fitted an upside down Yamaha R1 fork on an early 80'ties Kawa - it looks very dominating, very frankenbike-like! As to your question in your first post: Machining the hub was quite easy and only took 30-45 mins, whereas my machinist spend about 3 hours on the spacers.

@glaede: You can convert to dual disc in several ways. My way incl. changing the fork, machining hubs, spacers and all is by far the most work and the most expensive (but maybe the most fun too ;-) You'll also find several post in the forums about adding another 70'ties disc. I don't know how good it would be compared to my setup.  Probably just fine. BTW: Spend time on getting the bike running good, before all the cosmetic stuff! Hub and wheel are stock, yes. Would've liked to use some alu-rims, but couldn't really find any + I wanted to keep costs down. I'm not sure about the total costs - I'll add it up one of these days - but it'll probably be around USD 800-1000.
And yes, nice with some more danes here. There are a few actually, including Strynboen, with the most awesome written english I have ever seen.

Finally, thanks for all the thumbs up! Gets me motivated! Also, I really get a kick out of giving something back to the forum. I'll be back with more details this weekend.

[Viktor.J]

I see that you live in Copenhagen ! I Live near Malmö, let me know if you plan to drive over to Sweden this summer

[RAFster122s]

Work looks good, glad it didn't take a lot of machinist time; as it is expensive.
The FZ6 top triple tree is designed for handlebars and gives about a 2 inch rise from the top of the forks. It is a very lightly textured silver finish instead of black like the R6. It is a cast part and incorporates an ignition switch ring & mount in the front offset to one side. It uses allen head bolts for most of the fasteners. The handlebar clamp bolts have small silver plastic caps that insert into the heads and cover the bolt head and opening which would collect water.
David

[Glaede]

@glaede: You can convert to dual disc in several ways. My way incl. changing the fork, machining hubs, spacers and all is by far the most work and the most expensive (but maybe the most fun too ;-) You'll also find several post in the forums about adding another 70'ties disc. I don't know how good it would be compared to my setup.  Probably just fine. BTW: Spend time on getting the bike running good, before all the cosmetic stuff! Hub and wheel are stock, yes. Would've liked to use some alu-rims, but couldn't really find any + I wanted to keep costs down. I'm not sure about the total costs - I'll add it up one of these days - but it'll probably be around USD 800-1000.
And yes, nice with some more danes here. There are a few actually, including Strynboen, with the most awesome written english I have ever seen.

Well, too late, I'm almost done with the cosmetic stuff ;-) The thing is it keeps fouling the plugs, so I replaced the plug caps and airfilter and now I'm waiting for my new plugs to arrive. Hopefully that will help. Hehe I know Strynboen from knallertforum.dk ;-) He has helped me out before..

I think I'll keep it stock and just put an extra disc and caliper on. Do you wanna sell your stock stuff maybe?

[Franky]

@Glaede: I know, I also have a tendency to do the cosmetics first... We should be able to figure something out with my stock parts - I'll PM you.

@RAFster122S: I'll look into the different top. Sounds like a perfect fit. Does it bolt right onto the R6 fork I wonder?

@VictorJ: I'm actually going near Linderöd this weekend. The mopedclub (www.teufelskerle.dk) and I are going to visit a guy that has his own dirttrack curcuit and a barn full of trailbikes and mopeds. Last year was some of the most stupid-fun-awesome time of 2012!

I'm going to work some more on the bike today, and hopefully get it 100% ready for the road. Can't wait - it's been on the bench all winter and spring...

[Franky]

A small update!

The summer has been amazing here in Denmark, so lots of riding and no use for a front fender. But, fall is coming soon, so i finally got around to fitting a fender. At the same time, I integrated a pushbike speedo into the design - it's actually quite nice to be able to see just how much I'm speeding ;-)


Mocking up!


I later connected the two hoops - more stable


Finish is not excellent, but a rough finish seem to fit this bike well!



Note that most pushbike computers top out at 99 km/h, but some go to 199 km/h - get the latter and you're good! Mine is this one:

[Franky]

In FunJimmy's original build, he had to shave off quite a bit of the calipers to make enough clearance for the spoked wheels.

It turned out, I only had to shave of a little of the right caliper to make things work. Everything looks quite balanced though, so I can't really tell why the left side didn't need any extra clearance...



So I have been riding this setup all summer now, and the new fork and brakes are performing amazingly well.  The fork feels good going into turns and not too stiff as Jimmy mentioned in his thread. But, I'm also 191 cm (6"3) and 95 kg (200 pounds) + I may not be a good enough rider to be able to properly judge such things!

I'll update the thread with some pics of the 'finished' bike soon. (Never ending build ;-)

[RAFster122s]

Jimmy went with a wider front rim, WM3 if I recall correctly, thus the need to shave more...

[jtran000]

man, this is sick.  keep it up!  I just got my bike together after rebuilding the forks and putting on new tires.  Brakes are next on my list cause they feel like marshmallows.  working up the balls to do a conversion like this.

as always, more pics!!!

- Jtran

[Franky]

That's right RAFster - he has the nice alloy ones... However, it's not the rim that need the extra clearance, but the spokes. If our hubs are the same, the needed clearance would also be the same I take it?

Maybe the dimensions (width) of the R6 forks are a little different. Mine is a slightly newer than his.