1979 CB750F Tracker (maybe?)
- Thread starter jordandogtown
- Start date
I finally got some time to start tinkering around with some mounts. I know the angles will be different than what they were on the CBR, but my position is everything else on this bike is different from the CBR as well, so I'm just going to employ trial and error. RaceTech offers enough support that I can rebuild the shock slightly stiffer/softer if needed, and there's a bit of adjustment built in already. My first plan is to tack everything together where it "looks right" and see how the bike sits and the swingarm moves, then adjust if necessary. Sure, I can't see all the hidden internal engineering forces but I'm (barely) confident enough in my years of hucking dirtbikes through the air to get it close (read: somewhat safe).
I pulled the spring and compressed the shock by hand, and the linkage/shock shaft followed an identical path as they did in the lower CBR position, so I'm not too worried about binding. FWIW, the CBR application was angled at 25o, and my current angle is 35o. The hot upgrade for Suzuki TL1000s are to swap this shock and run it at nearly 90o, so I think it's worth a shot.
Dogbone mounts, which will be welded to a 0.125" plate instead of directly to the OE cross bar. Distribution of forces and what-not.
Don't knock my fab skills, all I have is a $20 Ryobi angle grinder and a HF belt sander. But I am having a blast with it
I pulled the spring and compressed the shock by hand, and the linkage/shock shaft followed an identical path as they did in the lower CBR position, so I'm not too worried about binding. FWIW, the CBR application was angled at 25o, and my current angle is 35o. The hot upgrade for Suzuki TL1000s are to swap this shock and run it at nearly 90o, so I think it's worth a shot.
Dogbone mounts, which will be welded to a 0.125" plate instead of directly to the OE cross bar. Distribution of forces and what-not.
Don't knock my fab skills, all I have is a $20 Ryobi angle grinder and a HF belt sander. But I am having a blast with it
I'll be tied up for the next ~week or so but I did finally dip into the piggy bank. I couldn't wait any longer.
(gratuitous cell phone close-ups to follow)
(gratuitous cell phone close-ups to follow)
Very interested to follow how you work out that mono shock - I've worked on my KLR's mono but haven't mustered up the stones to build my own. I submit an official request for maximum overdrive photo documentation please 8)
Bet you're stoked with those new Keihins
Bet you're stoked with those new Keihins
I managed to find some time this weekend to get everything roughly tacked together. I put the spring back on, bolted the shock up, and to my surprise - it kinda worked? The swingarm angle matches the CBR, raising the rear of the CB slightly (rake and trail figures have been addressed). The shock definitely feels stiff, but I am missing some significant weight not including the rider. I'm not able to compress it very much without a subframe, but I'm encouraged enough to leave this iteration as is for now.
Thanks Jim, I'm cautiously optimistic and very excited.
Best case - it handles a little better than stock, maybe gets me 1-3 high fives from fellow builders
Worst case - bike wobbles uncontrollably as soon as I start it up and I turn it into something else. I'm young and dumb enough to keep rolling
Best case - it handles a little better than stock, maybe gets me 1-3 high fives from fellow builders
Worst case - bike wobbles uncontrollably as soon as I start it up and I turn it into something else. I'm young and dumb enough to keep rolling
Oh boy, has this project been turned up on it's head. I'll try to keep this brief:
My original plan was to use the CBR swingarm/monoshock and keep the original CB bicycle wheels. I hadn't seen it done, and thought it would be a cool compromise. This bike won't see a track, and probably <500 miles annually, so I wasn't very concerned with the drawbacks of the OE wheels. The wheel would fit in the swingarm fine, but needed some spacers and a few new ideas for the brake.
Spacers - no problem
Brake - sort of a problem
I experimented with adapting the CBR brake caliper to the CB wheel and neither of them liked it. I threw around the idea of making a custom hanger for the CB brake but kept running out of room. I checked Ebay to see the original CB hangers aren't that sought after, so I got the hacksaw out (Honda purists look away now... if there are any left in this thread ;D)
Aside from making a new art-deco paperweight, I removed enough material to fit the hanger and get the wheel mounted. It definitely looks sketchy, but I believe there was enough material there to anchor the brake since the hanger has a built in spacer. I think it would have worked, but either better judgement (oh no, am I getting old?) or just my propensity to change my mind; I decided to scrap the first idea and jump to plan B. To be fair, I did warn you on page 1.
Pros of keeping original wheels:
1. Different from all the hipster conversions
2. Symmetry
3. ??
Pros of converting to modern wheels:
1. More/better tire options
2. More/better brake options
3. Handling
4. Shiny
5. Finally doing something I always wanted to but was too broke/intimidated (YOLO?)
My original plan was to use the CBR swingarm/monoshock and keep the original CB bicycle wheels. I hadn't seen it done, and thought it would be a cool compromise. This bike won't see a track, and probably <500 miles annually, so I wasn't very concerned with the drawbacks of the OE wheels. The wheel would fit in the swingarm fine, but needed some spacers and a few new ideas for the brake.
Spacers - no problem
Brake - sort of a problem
I experimented with adapting the CBR brake caliper to the CB wheel and neither of them liked it. I threw around the idea of making a custom hanger for the CB brake but kept running out of room. I checked Ebay to see the original CB hangers aren't that sought after, so I got the hacksaw out (Honda purists look away now... if there are any left in this thread ;D)
Aside from making a new art-deco paperweight, I removed enough material to fit the hanger and get the wheel mounted. It definitely looks sketchy, but I believe there was enough material there to anchor the brake since the hanger has a built in spacer. I think it would have worked, but either better judgement (oh no, am I getting old?) or just my propensity to change my mind; I decided to scrap the first idea and jump to plan B. To be fair, I did warn you on page 1.
Pros of keeping original wheels:
1. Different from all the hipster conversions
2. Symmetry
3. ??
Pros of converting to modern wheels:
1. More/better tire options
2. More/better brake options
3. Handling
4. Shiny
5. Finally doing something I always wanted to but was too broke/intimidated (YOLO?)
After convincing myself it's not the end of the world to do something that's already been done, I began searching for some short and fat wheels. The rear wheel was a song, and came with a rotor that may have been made out of rust to begin with. Lucky for me they are a lot easier to find than 750F rotors. The wheel dropped directly in, giving me a nifty little rear brake, comfy tire options, and 2/3s of the way to a 530 conversion.
Disclaimer: wheel isn't lined up in this photo, missing the caliper hanger.
Disclaimer: wheel isn't lined up in this photo, missing the caliper hanger.
That's the ticket.
Now the front. I know, I know, google "super cool coffee shop guy on rad motorcycle" and every result will be a CB750 with a GSXR front end. I'm not reinventing the wheel here (ba-dum, tiss) just trying to build a bike that looks alright and rides alright, and maybe impresses my wife enough that I can get myself out of the dog house when it's all said and done. I had a certain .45 caliber hunk of 'Merican freedom that I planned on liquidating for this build anyway. Turns out, it was enough to buy the full conversion, minus bars which I can't decide on yet, with enough left over to pay for a steak dinner for two (dog house, working on it).
Forks: 2005-2006 GSXR1000, KYB 43MM, Kashima coated, upgraded internals
Brakes: Tokico 4 pot calipers
Wheel: Reproduction OEM replacement. New and straight
I'll be using the cognito conversion stem and bearings, and according to my numbers and the RB Rake and Trail calculator, I'm right on the money. Steering should be sharpened up just a hair, while leaving me plenty of room to adjust the front or back.
So here we are. Tracker/superbike/café racer/muscle bike/seen it already/$300 at the scrap yard? No idea. But it's fun, and I love it.
Forks: 2005-2006 GSXR1000, KYB 43MM, Kashima coated, upgraded internals
Brakes: Tokico 4 pot calipers
Wheel: Reproduction OEM replacement. New and straight
I'll be using the cognito conversion stem and bearings, and according to my numbers and the RB Rake and Trail calculator, I'm right on the money. Steering should be sharpened up just a hair, while leaving me plenty of room to adjust the front or back.
So here we are. Tracker/superbike/café racer/muscle bike/seen it already/$300 at the scrap yard? No idea. But it's fun, and I love it.
Man the wheel looks FAT compared to the OEM Comstar. Looks like a spacing issue and it's a bit offset.. keep tinkering it'll come into sight.jordandogtown said:After convincing myself it's not the end of the world to do something that's already been done, I began searching for some short and fat wheels. The rear wheel was a song, and came with a rotor that may have been made out of rust to begin with. Lucky for me they are a lot easier to find than 750F rotors. The wheel dropped directly in, giving me a nifty little rear brake, comfy tire options, and 2/3s of the way to a 530 conversion.
Disclaimer: wheel isn't lined up in this photo, missing the caliper hanger.
Check out Sprocket Specialist for help with the 530 chain conversion. Great selection there, and can custom cut you a sprocket. Also EBC I believe still offers there Pro Lite line for OEM rear wheel on 79 750 F platform if you go that route.. like 229.00 .
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KPSguy said:
You're right, the wheel was just tossed on the axle in that photo. I should have realized it and taken a better one, but there was a lot nuts and bolts flying around and that's the one I ended up with. The wheel tracks straight and true ;D
I've been digging around for front sprocket options, and there seem to be plenty out there. Some Triumph and VFR sprockets should bolt right up. A lot of good info on the 1100F site
cb360j said:
Don't make me talk about it :'(
It was a Kimber Pro Carry 1911 HDII. I'm more of a hand-me-down shotgun kinda guy but I was in love with the Kimber. I swapped around for it around the same time I bought the 750, and kept it for a nest egg of sorts. Still hurt to see it go. Hopefully the wind in my beard aboard whatever this bike turns into will make me feel a little better.
Not cheap by any means, but Cognito sure puts out some high quality parts. I'm going to drool over it a little longer then press it in and spend all weekend mashing parts together
