omgwtfbbq!
Active Member
Hey guys, been a lurker for a while but things are finally rolling with my build so I can finally contribute!
Where better to start than the beginning:
The story I was told is the original owner bought two sequential serial number CB750s new in 1981 so him and his wife could go riding together. They didn't, for whatever reason. One sat in the yard, one in the garage under a tarp. Fast forward 30 years, a passing tow truck driver sees the one in the yard. He knocks on the door, offers to buy it. The owner agrees and says there is another one in the garage. Tow truck driver calls his buddy who promptly comes and buys it. His buddy rebuilds the carbs, relines the fuel tank, changes the plugs, oil and filters, and shes back to life. Then he gets a massive pay cut at work. He puts it up for sale. I enter the picture, drive an hour in a uhaul truck and take her home. The original owner put hard bags on the rear, so I have to source new blinkers. Previous owner changed the bars so I had to grab some cheap mirrors. But she purrs like a walrus with just 2200 miles on the clock, just need to replace the 34 year old tires and she'll be good to go.
I put just shy of 2000 more miles on her over the course of 6 months, change the oil, replace fork seals and the battery along with the starter solenoid. Take a look at the internals and everything looks brand new in the engine. 34 years and not a single flake of rust on anything important.
That brings us to today.
My rough inspiration for the bike was this image on google:
The GF demands I run a brat seat so she can ride along, my only demand is that the subframe triangle remain free of clutter.
The plan:
I want to do a very modern build. All LED lighting, modern suspension, bespoke carbon fiber engine/clutch/sprocket/etc covers to reduce weight, modern instrument cluster, more aggressive riding position, the usual café bits with a more modern than usual twist.
My degree is in Mechanical Engineering with a focus in High Performance Vehicles, so I don't just want to screw around and make a hipster bike; I want to actually see results.
With that in mind I took some preliminary measurements. The bike as I bought her weighs 540lbs wet, and makes 72whp (I'll upload the dyno graph as soon as I remember to bring it to work with me). I plan to re-weigh and re-dyno the bike after each major applicable change to see what impact I'm actually having.
I've started a preliminary design for a custom exhaust and intake system. The final design and manufacture of those components is next on the list after the suspension gets sorted. I'd like a titanium exhaust, but I also like eating things that aren't ramen, so I need to find a good compromise there.
Today I picked up these:
The complete front end off a 2009 Yamaha R6. I was trying to keep it all Honda parts, but my guy had no idea when he was gonna get a complete front end in, and the cost would have been the same or more. Plus I'm a sucker for gold forks.
Soon.
I got home and patiently waited for my mailman to bring me the next piece of the puzzle:
Conversion stem and bearings!
The package arrived about an hour before I had to leave for work, so I rushed off to use the 20 ton press.
Out with the old...
...and with a little persuasion...
...in with the new.
Now I'm sitting in my office watching the clock waiting for quittin' time. Tomorrow I hope to slap the front end on and start sorting out the wiring with the new controls, as well as the throttle/clutch cables. Then I'll be on the lookout for parts for the rear. After reading tons of posts here and on CB1100F I think I've decided to go with a Blackbird swing arm and dual shocks. I like the retro look of the dual shock, and dislike the work it would be to properly install most monoshock suspensions. I considered a single sided swingarm for a bit, but I don't think the CB frame needs any more torsional stress than it deals with already.
Assuming I keep the stock rear, I'm going to be reducing my trail to about 90mm according to some off the cuff CAD drawings. That sounds like a riot. I need a 2.3" drop in the rear to bring the trail back up to 100mm, which is probably going to have a slight impact on the ground clearance. We'll see how that goes. More to follow.
Where better to start than the beginning:
The story I was told is the original owner bought two sequential serial number CB750s new in 1981 so him and his wife could go riding together. They didn't, for whatever reason. One sat in the yard, one in the garage under a tarp. Fast forward 30 years, a passing tow truck driver sees the one in the yard. He knocks on the door, offers to buy it. The owner agrees and says there is another one in the garage. Tow truck driver calls his buddy who promptly comes and buys it. His buddy rebuilds the carbs, relines the fuel tank, changes the plugs, oil and filters, and shes back to life. Then he gets a massive pay cut at work. He puts it up for sale. I enter the picture, drive an hour in a uhaul truck and take her home. The original owner put hard bags on the rear, so I have to source new blinkers. Previous owner changed the bars so I had to grab some cheap mirrors. But she purrs like a walrus with just 2200 miles on the clock, just need to replace the 34 year old tires and she'll be good to go.
I put just shy of 2000 more miles on her over the course of 6 months, change the oil, replace fork seals and the battery along with the starter solenoid. Take a look at the internals and everything looks brand new in the engine. 34 years and not a single flake of rust on anything important.
That brings us to today.
My rough inspiration for the bike was this image on google:
The GF demands I run a brat seat so she can ride along, my only demand is that the subframe triangle remain free of clutter.
The plan:
I want to do a very modern build. All LED lighting, modern suspension, bespoke carbon fiber engine/clutch/sprocket/etc covers to reduce weight, modern instrument cluster, more aggressive riding position, the usual café bits with a more modern than usual twist.
My degree is in Mechanical Engineering with a focus in High Performance Vehicles, so I don't just want to screw around and make a hipster bike; I want to actually see results.
With that in mind I took some preliminary measurements. The bike as I bought her weighs 540lbs wet, and makes 72whp (I'll upload the dyno graph as soon as I remember to bring it to work with me). I plan to re-weigh and re-dyno the bike after each major applicable change to see what impact I'm actually having.
I've started a preliminary design for a custom exhaust and intake system. The final design and manufacture of those components is next on the list after the suspension gets sorted. I'd like a titanium exhaust, but I also like eating things that aren't ramen, so I need to find a good compromise there.
Today I picked up these:
The complete front end off a 2009 Yamaha R6. I was trying to keep it all Honda parts, but my guy had no idea when he was gonna get a complete front end in, and the cost would have been the same or more. Plus I'm a sucker for gold forks.
Soon.
I got home and patiently waited for my mailman to bring me the next piece of the puzzle:
Conversion stem and bearings!
The package arrived about an hour before I had to leave for work, so I rushed off to use the 20 ton press.
Out with the old...
...and with a little persuasion...
...in with the new.
Now I'm sitting in my office watching the clock waiting for quittin' time. Tomorrow I hope to slap the front end on and start sorting out the wiring with the new controls, as well as the throttle/clutch cables. Then I'll be on the lookout for parts for the rear. After reading tons of posts here and on CB1100F I think I've decided to go with a Blackbird swing arm and dual shocks. I like the retro look of the dual shock, and dislike the work it would be to properly install most monoshock suspensions. I considered a single sided swingarm for a bit, but I don't think the CB frame needs any more torsional stress than it deals with already.
Assuming I keep the stock rear, I'm going to be reducing my trail to about 90mm according to some off the cuff CAD drawings. That sounds like a riot. I need a 2.3" drop in the rear to bring the trail back up to 100mm, which is probably going to have a slight impact on the ground clearance. We'll see how that goes. More to follow.
