Topic: R6 Fork Swap information gathering

[FunJimmy]

I have a set of risers from a CB350 that bolt on. As long as the shaft is long enough, why couldn't I drill the upper triple and use them?

Sure. Can't see any reason why not.
Looks like you scored that R6 front end. Touché

[754]

Depends if you are drilling through a rib or not in the tree, they can be thin in certain areas, and bard to get a flat seat for the fastener.. Have a look at the underside.

[Scott S]

Speedo drive was my issue as well. It's difficult finding a 20mm ID mechanical speedo drive. Kawasaki ZRX models use a mechanical speedo drive. I had considered investigating at the time but went the GPS route instead. Still might be worth considering.

 I actually see a few Kawasaki speedo drives. The 20mm I.D., is that to clear the new, larger axle?
 What about speedo drive ratios? Do they differ among brands? In other words, if I got a ZRX speedo drive, would I need a ZRX speedo?

 Also, didn't one of you mention using a Motolanna fender? Which one did you use? They offer several.  I'm guessing it's one with the "even" mounting holes to match up to the ears on the R6 forks.

[Scott S]

 I found http://www.dotheton.com/forum/index.php?topic=20952.0 on DTT. Looks like there are lots of 20mm axle speedo drives to choose from, even a few Hondas.

[Camrector]

I used a mottolanna fender. My bud took some measurements and 3D printed some mounts.

[Scott S]

I used a mottolanna fender. My bud took some measurements and 3D printed some mounts.

 Ah, so you just used the fender portion and not the mounts.

[FunJimmy]

I found http://www.dotheton.com/forum/index.php?topic=20952.0 on DTT. Looks like there are lots of 20mm axle speedo drives to choose from, even a few Hondas.

Good score Scott. Now let's hope one of those has a speedo drive with the correct ratio.

[Scott S]

I found http://www.dotheton.com/forum/index.php?topic=20952.0 on DTT. Looks like there are lots of 20mm axle speedo drives to choose from, even a few Hondas.

Good score Scott. Now let's hope one of those has a speedo drive with the correct ratio.

 That's what I'm trying to find out now. Wonder how I can figure that out?

[Camrector]

I used the fork leg tabs, but still needed to make an adapter to fit the fender mount. I used the motolana xs650 fender. It was close to bolt on but not quite.

[Scott S]

  I have found that Honda (and probably Yamaha and Suzuki) were 2240 = 60mph. Kawasaki is 2440rpm = 60mph.
 While the ratios were somewhat standardized by manufacturer, the drives were slightly different to account for wheel size/diameter.

 My task now is to find a bike that used a 20mm axle and an 18" or 19" front wheel.

 Did any of the bikes in this list use 18" or 19" wheels?

20mm
Honda CB400 F 89-90, CBR600 Hurricane 89-90, CBR600 F
Hurricane 91-96, CBR600 SE 96, VT600 Shadow 88-97, NT650 Hawk
88-91, CB750 SC 91-93 & 95-97, RVF750 R RC45 94-95, VF750
C/C2/D 94-97, VFR750 F 86, VFR750 F Interceptor 88-97, PC800
Pacific Coast 89-90, CBR900 RR Hurricane 93-97, CBR1000 F
87-88 & 90-91 & 93-96, CBR1100 XX Blackbird 97, VT1100 C
Shadow 87-96, VT1100 C2 ACE Shadow 95-97, GL1500 88-97, GL1500
Valkyrie 96-97, Honda VF750 C/C2 98. Kawasaki ZX750 Ninja ZX-7
89-90. Suzuki GSX-R750 88-92, GSX-R750 W 92-95, Honda CR125
00-03, CR125 95-97, CR250 95-97, CR250 00-03, CR500 R 95-97.
Kawasaki KX125 93-97, KX250 93-97, KX500 94-97. Suzuki RM125
96-97, RM250 96-97. Yamaha YZ125 96-97, WR250 Z 97-98, YZ250
96-98, Kawasaki ZX600 E ZX-6 93-98, ZX600 F ZX-6R 95-97, VN800
Vulcan Classic 96-97, VN1500 D 96-97, Yamaha YZF750 R 94-97,
FZR1000 94-95, XVZ13 Royal Star 96

[Camrector]

Or be like Dylan and go electric.

[Scott S]

 Looks like most of the Hondas on that list use a 17" front tire.

 The VT600 used a 19" (with one model having a 21").
 CB750SC 91-93 had a 19"
 CB750SC 95-97 had an 18"
 GL1500 88-97 used 18"

 Now....to try to confirm speedo ratio!

[Scott S]

Or be like Dylan and go electric.

 Always a possibility....and probably the easiest route. But I'd LOVE to have the stock '71 CB500 gauges from my first ever SOHC4 on there!

[Scott S]

 I think the Nighthawk SC might be the answer. Used a 20mm axle, Honda speedo ratio and 19" or 18" front wheel.

[Scott S]

 I notice that in this diagram, Jimmy makes note that the spacer(s) are for single disc. What's different for dual vs. single disc?

[FunJimmy]

I notice that in this diagram, Jimmy makes note that the spacer(s) are for single disc. What's different for dual vs. single disc?

Scott,

I can't take credit for the drawings. Franky was kind enough to provide them.
He incerted a picture of the spacers (from my build thread) for reference.
If you look closely you will notice that only one of the spacers has been drilled and tapped for the rotor. I could easily drill and tap for a second rotor if required.

[Scott S]

 Ahhh..... just noticed that you don't use the through bolts to secure the rotor like stock. Just tap both sides for dual discs, then.....gotcha.

[Scott S]

 One thing I haven't seen mentioned (two, actually):

 * What length/size are the bolts used and where did you find them?
 * Does anyone remember exactly what bearings you had to use for the stem? And for that matter, the hub, too.

[Johnny340]

Is there any concern about these old frames handling the increased stress from all that stopping power?

I'm also upgrading the font end on my bike (GSXR front on a 750 though)

[SOHC4 Cafe Racer Fan]

Is there any concern about these old frames handling the increased stress from all that stopping power?

I'm also upgrading the font end on my bike (GSXR front on a 750 though)

I've never heard of a frame failure (cracked welds or bent tubes) from the added braking force.  Most of that force is distributed across the forks but some gets transferred to the head stock.  I suppose you could reinforce the welds to the head stock.

[540nova]

You would do an endo before you overstressed your frame.


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[Scott S]

 So... I have these Lester's......

 How ignoramus of me would it be to use them on the R6 swap?

 I ask because if you're going with a modern front end, weight savings is usually part of the deal. Which means aluminum rims (Sun, Excel, etc.). But I have the Lester's. And I like them. And I can sorta visualize the bike with them in my head.

 Pro: They're Lester's. I already own them. They're cool.
 Con: Not as light as aluminum wheels. The front hub would have to be modified to use it on the R6 front end, so it would be no good for anything else. Not sure if the machinist could even trim the hub, being that it's part of the wheel.

[calj737]

I wonder what true weight savings occur with modern front end swaps. The inverted forks seem to be much heavier that stockers to me. Sure, the rims are lighter, and depending upon whose hug you use, it can be lighter (the Cognito hub is definitely heavier than stock) and then you add 2 smaller calipers (weight push or perhaps a touch more) and 2 rotors (got to be a bit of savings there). So in the end, is it truly a weight savings? Defintely better braking and suspension, but I am dubious over weight gain.

If the R6 are conventional, then perhaps they are a light package?

[540nova]

Agree with Cal. In the end, will +-10 lbs really make a difference? I'd wager you would not be able to tell the difference. Do it for the braking, I wouldn't worry about the weight.


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[Scott S]

 Cal, yes....the R6 forks are conventional.