My CB-1 F2/F3 wheel swap and other mods

[eyhonda]

I got my bike late last year and have been upgrading it with parts from other Hondas.  During the recent lockdown, I've been busy doing some more work.   Here is the list of most of the mods:

Rizoma mirrors.
VTR1000 clip-ons.
VTR1000 switches, modded to fit OEM harness.
VTR1000 throttle tube and housing.
Pazzo levers.
VTR1000 choke cable & bracket.
600F3 front wheel with new bearings and CB-1 310mm rotor.
VTR1000 upper cartridge tubes with CB-1 lower stanchions and brake caliper.
600F2 rear wheel with custom aluminum spacers and collar.
Dunlop Q2/Q3 tires. 120/70 and 160/60.
520 chain conversion. JT 15t (CBR500) and Vortex aluminum 38t rear.
CBR1100xx shock.
CBR900rr side stand. Need longer stand for longer shock.
Vortex CBR929 rearsets, re-drilled to fit.
Rear HRC style reservoir.
CBR929 gold rear brake caliper.
Graves spool kit, redrilled/tapped for 8mm spool bolts.
Modify harness for MOSFET regulator.
LED turn signals and TST electronic relay.

I still have to finish the exhaust and tune the suspension (especially the forks).  I'll fab a mid-pipe to a high mount slip-on can.   Stay tuned.

https://flic.kr/p/2iUvUHM
https://flic.kr/p/2iUvUxg
https://flic.kr/p/2iUt8fi
https://flic.kr/p/2iUxtBb

Eric

[stussels]

thats looking the business

[eyhonda]

Thank you, stussels!  Waiting for my new TIG welder and I can get the exhaust mid-pipe done. I will either do an OMT or Kerker can.

[a_morti]

Looking good!

I tried VTR1000f / CB-1 hybrid forks once, they had way too much damping. I didn't have time to get into it, just undid the mod.

How hard was it to get an f2 rear wheel mounted? Just the new spacers or any machining of the cush hub area etc required?

[eyhonda]

Haven't ridden it yet but I will play with it then.    The front was bolt in but the rear needed custom spacers machined.  2 on the outside of the bearings and the one collar between the cush and wheel.  Bearings too to make it fit the OEM 17mm axle down from 20mm.  A small sleeve was needed to keep the 20mm f2 spacer inside the wheel from moving around.  It would have been better to lathe down the 17mm CB-1 part, which is longer than the f2.  Tire selection is important as the tire, though centered is very close to the swingarm.  I grinded down the welds smooth inside the swingarm to buy a couple mm's of clearance.    The 520 chain is pretty spot on for the chain line too.

I'm also planning to adapt a Ducati 999 Brembo 4 piston/4 pad axial caliper.

[a_morti]

I grinded down the welds smooth inside the swingarm to buy a couple mm's of clearance

Grinding structural welds would make me nervous  

According to this, the 160/60-17 is 6.67" "actual" width. That's 169.4mm.
https://www.dunlopmotorcycletires.com/tire-line/sportmax-q3-plus/

This guy measured 175mm on a 4.25" rim, so even more exaggerated.
https://www.supermotojunkie.com/threads/actual-tire-width-dot-and-race-slick.145216/post-1636113

I'd have rather trawled through specs to find the narrowest 160, or fit a 150.

The front was bolt in

Did you drill and tap the CBR front wheel to 8mm for the CB-1 disc? Or did you find some m6 bolts with 8mm shoulders of the right depth? I'm hoping you've not put 6mm bolts in 8mm disc bolts and called it done.

the rear needed custom spacers machined

You could also make those outside wheel spacers as (longer than usual) captive spacers. They'd go right through the CBR's original 20mm wheel bearings and the cush bearing and spacer to reduce the diameter to fit over a 17mm spindle bolt, and protrude into the central spacer by a few mm from each side to keep that in place. This would only require two turned pieces, and save the trouble of replacing the bearings. As a bonus, it becomes easier to remove and refit the wheel as your spacers aren't always dropping on the floor.

I'm also planning to adapt a Ducati 999 Brembo 4 piston/4 pad axial caliper

I'd also consider a 600rr/929/954/RC51 front caliper. This will fit on to a VTR1000F fork leg with just a tiny bit of grinding on the fork leg. Looks nice and Nissin/Honda is "just right". I have used a caliper adaptor before but they always look kinda ugly. It will need an upgrade to a 1/2" master cylinder to work right.

CBR929 gold rear brake caliper

You may also want to fit a smaller, tidier/sportier rear disc. The 220mm disc from a CBR900 (also used on tons of other Hondas) fits the CB-1 wheel. I'm not sure if there's an easy caliper hanger for a 220mm disc that'll line up to the CB-1 swing arm. For an easier job, the Hornet 900's 240mm disc is a direct fit, but looks more modern.

[eyhonda]

The grinding of the welds was well away from the structural part.  There was a lot of extra weld towards the rear of the swingarm that lines up with the sidewalls.  I didn't grind away the welds completely. Just smoothed them.   Yes, that would be dangerous if I did remove the welds.

I probably could have checked specs on which tires.  It was what was available at my tire guys shop and at first check, it cleared but barely. 

The front disc was easy to spot the difference.  I was going back and forth on the two choices that you also mentioned.  I finally went with the shouldered bolts.   I didn't want to drill and tap.  That's a no going back option.  I figured if 6mm is strong enough for a VFR, it should be ok for the smaller cb1.  Maybe, it is 8mm because it is a single vs dual?   

Yes, that is a better way to have designed the spacers.  Good idea.  Dropping the spacers on the right - yes that was a PITA.

Changing the rear disc wasn't a priority (yet).  I didn't want to relocate the caliper for a smaller disc. 

The front fork lowers are CB-1.  So stock caliper for now.  I have VTR calipers too.  The Brembos mount weirdly and yes the adapter will look kinda chunky there.  Not decided which route.  I will consider the VTR calipers which is likely the same as what you mentioned (CBR, RC, etc).  It might mount more elegantly with a smaller adapter.  It will depend which direction the bolts will mount.

I wanted minimal downtime and most of the work was in the late winter/early spring.   But now, she is stubborn and won't start.   No spark issue I am chasing.   I just pushed her into the trailer for now until I get time.    Mostly riding the Hawk and VFR for the time being.   Plus the CB-1 still has no exhaust.   

[a_morti]

Not really sure why the CB-1 has 8mm bolts versus 6mm found on dual disc bikes, but I guess it could be due to sharing or not sharing the load. I've previously drilled a CBR400 front wheel to 8mm for the CB-1 disc, it worked just fine. Of course if I had subsequently wanted to use dual discs I'd have had to figure out a solution such as drilling the disc mounting holes out to 8mm to match.

The VTR calipers are the "batwing" design like an early CBR900. They are pretty decent if in good condition, but they have steel pistons which can corrode, whereas the later CBR929/954 etc calipers have teflon-coated alu pistons which cannot corrode, same as brembo. Those earlier calipers have smaller pistons which should be fine with the CB-1's OEM 11mm master cylinder. Also they fit 1:1 on VTR forks without any grinding (even if the later calipers don't need much material removing, they do need some taken off). It's easy to mount a CB-1 mudguard to VTR forks. Have you seen this one before?

I've used an adaptor before, but they never look great IMHO.

It was made by Spiegler, they don't have them anymore. The bike is long since sold on, I can't measure anything for you.

Best of luck with the no-spark condition. If you have any questions, you can ask here or the Facebook group (which is way more active).