CB400SF NC31 - old but not obsolete :)
Posted: Wed Jan 16, 2019 3:11 pm
I’ve made up my mind to share the story of how I build my CB400SF NC31 bike.
I brought this 1993 bike from Japan to become my first ride. I like compact and fast sporty cars like MX5 or MR2 but there is few such classic bikes of this sort in Russia. Motards were not an option. So, things have come to the fact that I had to built one myself. As a result I should have a compact classic sleeper bike. The construction is in progress now, but I've already got something to show.
I will split the story into several parts highlighting bodywork, suspension, brakes upgrade, engine etc.. The photos maybe a little bit dated and therefore the same parts would differ in colors on some pics.
I used to drive it daily for 2 years until it was literally torn down to a single screw.
Okay, part one is about the brakes.
AsI had no specific plan to follow -I knew that I had to start with brakes upgrade.
Brakes and suspension is a starting point of any decent project.
I had no particular complaints about the stock brakes: when everything works properly, good pads are installed.
The only problem was that the suspension was a little bit soft and tended to nod.
I was searching yahoo auctions for some 6 pots calipers to install when my friend brought me a 1992 GSX1100 caliper to check. Surely they were in awful condition. I had to refurbish them.
Ordinary 4 pots brakes, the total cross area of the pistons is about 20% more than in the stock one. The pads are larger although this means nothing by itself.
I made test brackets using 3D printer.
Then I CNC machined brackets from aluminum alloy (I believe it’s almost like 2024-T3511) when all dimensions were corrected.
In addition, I installed main brake cylinder taken from the Kawasaki ER-6. This successfully complemented the increased need for pumping brake fluid. Plus I liked the lever adjustment wheel on it.
Of course, calipers were fully rebuilt.
Powder coated and used PTFE line in addition. Titanium banjo bolts and disk rotors bolts were also used. I just like the looks.
Rear brakes and the anti-lock system
Despite the relatively low mileage (around 50000 km) the rear caliper was already tapping. When driving bumps, you could hear the clatter from the rear end.
Inspection showed significant caliper pin seat wear.
I purchased on yahoo a rear caliper with an ABS bracket assembly with minimum mileage and an ABS sender included.
I also bought an almost new 2015 NC42 rear wheel with factory tire and swing arm from NC42, too. It turned out relatively cheap and timesaving deal when it comes to ABS installation.
Rear caliper was rebuilt as I had to paint it too.
I was looking for an anti-lock equipped CB400 in Moscow but without result. Hence, I had to use trial and error method here. I bought a service manual for NC42 at the auction, where ABS error codes, its testing procedures and the like were described.
There was no problem with the rear rim: it used to be ABS equipped NC42. The front 3” NC31 rim was not designed for the installation of the ABS rotor. But it turned out that it was enough to rebore the holes in the disk from 5 to 6mm and the rotor was fitted flawlessly.
At first I thought to use Nissin made ABS modulator from Honda Fit Hybrid that share the same control board as Honda motorcycles but has 4 channels instead of 2.
I found it hard to simulate 2 additional ABS senders and bought a modulator from CBR250RR. It’s almost the same as the stock one for CB400SF. The difference is only in mount brackets.
Swing arm installation was tricky and there was not enough space for rear master cylinder.
There was no space for rear brake switch too. I decided to use brake pressure switches installed in ABS modulator intake lines then. It simplifies wiring too.
At the moment I am welding the underseat box, so the final looks will be posted later on.
In the next post I'll describe EFI installation and some plans about engine
I brought this 1993 bike from Japan to become my first ride. I like compact and fast sporty cars like MX5 or MR2 but there is few such classic bikes of this sort in Russia. Motards were not an option. So, things have come to the fact that I had to built one myself. As a result I should have a compact classic sleeper bike. The construction is in progress now, but I've already got something to show.
I will split the story into several parts highlighting bodywork, suspension, brakes upgrade, engine etc.. The photos maybe a little bit dated and therefore the same parts would differ in colors on some pics.
I used to drive it daily for 2 years until it was literally torn down to a single screw.
Okay, part one is about the brakes.
AsI had no specific plan to follow -I knew that I had to start with brakes upgrade.
Brakes and suspension is a starting point of any decent project.
I had no particular complaints about the stock brakes: when everything works properly, good pads are installed.
The only problem was that the suspension was a little bit soft and tended to nod.
I was searching yahoo auctions for some 6 pots calipers to install when my friend brought me a 1992 GSX1100 caliper to check. Surely they were in awful condition. I had to refurbish them.
Ordinary 4 pots brakes, the total cross area of the pistons is about 20% more than in the stock one. The pads are larger although this means nothing by itself.
I made test brackets using 3D printer.
Then I CNC machined brackets from aluminum alloy (I believe it’s almost like 2024-T3511) when all dimensions were corrected.
In addition, I installed main brake cylinder taken from the Kawasaki ER-6. This successfully complemented the increased need for pumping brake fluid. Plus I liked the lever adjustment wheel on it.
Of course, calipers were fully rebuilt.
Powder coated and used PTFE line in addition. Titanium banjo bolts and disk rotors bolts were also used. I just like the looks.
Rear brakes and the anti-lock system
Despite the relatively low mileage (around 50000 km) the rear caliper was already tapping. When driving bumps, you could hear the clatter from the rear end.
Inspection showed significant caliper pin seat wear.
I purchased on yahoo a rear caliper with an ABS bracket assembly with minimum mileage and an ABS sender included.
I also bought an almost new 2015 NC42 rear wheel with factory tire and swing arm from NC42, too. It turned out relatively cheap and timesaving deal when it comes to ABS installation.
Rear caliper was rebuilt as I had to paint it too.
I was looking for an anti-lock equipped CB400 in Moscow but without result. Hence, I had to use trial and error method here. I bought a service manual for NC42 at the auction, where ABS error codes, its testing procedures and the like were described.
There was no problem with the rear rim: it used to be ABS equipped NC42. The front 3” NC31 rim was not designed for the installation of the ABS rotor. But it turned out that it was enough to rebore the holes in the disk from 5 to 6mm and the rotor was fitted flawlessly.
At first I thought to use Nissin made ABS modulator from Honda Fit Hybrid that share the same control board as Honda motorcycles but has 4 channels instead of 2.
I found it hard to simulate 2 additional ABS senders and bought a modulator from CBR250RR. It’s almost the same as the stock one for CB400SF. The difference is only in mount brackets.
Swing arm installation was tricky and there was not enough space for rear master cylinder.
There was no space for rear brake switch too. I decided to use brake pressure switches installed in ABS modulator intake lines then. It simplifies wiring too.
At the moment I am welding the underseat box, so the final looks will be posted later on.
In the next post I'll describe EFI installation and some plans about engine