Intro
I am documenting a cafe rebuild of a 1974 Honda CB750 K4. Let’s call it a chopper rescue project. I have built many Hondas and British café bikes and frequent this and the SOHC forum often but have never posted a bike project from beginning to end until now, so here goes…
I will document the major portions of the build as reference for others doing the same, post problems encountered with my solutions and emphasize the non-stock custom work. Many areas of CB750 restorations are well documented on this forum need not be repeated (carb and tank cleaning, frozen brake caliper, etc).
History
Two years ago I bought a K4 and a K3 CB750 from dude out in the countryside for cheap. I had other project bikes in progress but the price was too good to pass up, so I bought them and stored the until this week.. The K4 turned over and had compression while the K3 was frozen. I spent an afternoon cleaning the carbs, tank, petcock, installing new battery, flushing the old oil and put the 4-4 exhaust from the K4 and fired her up. Tweaked it a bit and it idled and rode well, but the front brake caliper was frozen so I only rode a few miles on empty back roads to assess its condition. Solid motor, clean functional carbs, transmission crisp and smooth, crap brakes and tires and ugly as hell. A perfect candidate for a café rebuild. For the Honda purists, I am not destroying anything special, it is a Honda K4, not a Vincent, and there are thousands of these rotting away in barns, garages and backyards.
Life happened, several other bikes completed and sold, fell in love with a Norton, so I am finally making to the time to tear into this project. I have bought a mountain of new Honda OEM and aftermarket parts waiting for this bike. New rims, tires, spokes, all new cables, Fast from the Past rearsets, battery, pod filters, larger main jets etc.
Personal
I am a British bike junkie and build Honda cafes as my methadone and financial source to support my British habit. Like most everyone on this forum, I enjoy wrenching, building, restoring bikes and the pride and self-satisfaction of making something old beautiful again. It is my passion and hobby, but not my career. My day job is in the museum field and I am a trained archaeological conservator and work with high end art and priceless objects centuries and millenia old, so 30-50 year bikes are relatively easy and simple to work on. Free time is scarce for me and is spent either riding or restoring bikes to keep me sane and out of trouble. Cycle therapy.
Goals
My goal for this bike is to build a cafe racer in the true sense and spirit of the term: stripped down and fast with good handling to mimic the British track racing bikes of the 1950’s and 60’s. Appearance, though important, is secondary to function. There is more to a café racer than a bad black paint job, rearsets and an ugly seat on an ill running bike. I do crank up rebuilds on all my motors, complete rebuilds on my wheels (new bearings, spokes, rims and tires), meticulous electrical and carb work and work methodically, without shortcuts. The 74 K4 will be based heavily on two of my previous CB400F café builds; Honda Milano red tank, Manx seat, plain black side covers, black cylinder, clubmans, rearsets, 4 into 1 exhaust, rebuilt wheels etc. A strong and powerful girl in a sexy red dress. The K3 will have a strong Norton Manx and Triton influence (black hubs, front drum brake, black fenders, Manx seat, rearsets, clip-ons 5 gallon Manx tank, Dunstall and John Tickle style goodies etc). One of these two will have a GT550 4LS shoe front brake drum just like my Triton.
My first CB400f cafe build
Recent CB400f cafe
CB750 K4 as purchased in all its 1970’s chopperesque glory. Ugly, but got her running within an hour. A solid bike, but since it has been sitting for years I am going to build it from the crank up with all new gaskets, seals and replace the bearings as needed. Repaint cases, polish covers and rebuild carbs, paint frame, rebuild wheels etc, here we go…..
Finally, made the time to start this one. 6 uninterupted hours of bike time on a Friday and 8 hours on a Saturday-heaven! Stripped her to the frame, pulled the engine and pounded knee indents in the tank, first coats of filler and sanding.
I cleaned the exterior of the motor, pulled the carbs, soaked the cover screws in PB Blaster overnight and removed them with an impact driver. All but two screws came off easily. One screw on the breather cover got strippied and one on the stator was drilled and removed with a reverse easy out tool in a hand drill.
The stator and clutch covers were removed along with the carbs, clutch plates and basket, starter, oil pan and filters to lighten the motor before pulling it out of the frame. Two lifts and I got the beast out of the frame and on to a milk crate. It is still weighs more than I do.
Everything was cleaned, photographed, bagged and labeled. The frame and swing arm was an oily mess, but all that oil kept the rust at bay. Spiders were evicted.
Proper use of a self-service carwash....
Sump oil filter…. This is why I always strip my bikes down to the crank. You never know what has happened to your bike with the previous owners.
I have been waiting two years cut the rear hub out of the god awful, ugly 16’ Harley rim and fat tire. Why people insist on hobbling their machines with fat rear tires is beyond me. The hub will be highly polished, drilled with a few large holes with screens for ventilation, but will not have shotgun blast holes a la Carpy. I have a brand spanking new 18” DID rim, new spokes and Dunlop D404 waiting to surround the hub.
I picked up two Suzuki GT550 4LS front drum rakes recently. One, I bought a $200 parts bike to get it and the other I literally stole from someone on Craigslist who had no idea it was worth $300-400 unrestored (To thwart hate mail and possible theft charges I will not reveal the price). I collected all the necessary parts to install dual drilled front discs but I may go with the GT 4ls drum on this one.
The K4 tank was exceptionally clean and had one small dent, so I filled it, primered and painted it black. It is not pictured and I will save or sell it. For this project I used the tank from the K3. It was clean on the inside, but a Bondo queen on the outside and the tank badge holders were filled in. It was ugly and I had no problem smacking it with a hammer. I created a pattern outlining my knees, traced it on to the tank and pounded away with a rubber and plastic headed mallet. No problems, easy to do and both indents are symmetrical. The indents were filled with body filler and sanded twice. I layed down one guide coat of primer and sanded it to determine the high and low spots of the tank. I filled the lowspots, sanded again and it now has another guide coat. On more round of sanding and spot filling and then on to final prime, paint and clear.
I am busy this week and a have big pile of junk waiting for me this weekend. Frame to paint, tank to sand, prime, paint, clear and polish, motor to break down, rebuild, paint, polish...
Cannot wait, stay tuned…
I am documenting a cafe rebuild of a 1974 Honda CB750 K4. Let’s call it a chopper rescue project. I have built many Hondas and British café bikes and frequent this and the SOHC forum often but have never posted a bike project from beginning to end until now, so here goes…
I will document the major portions of the build as reference for others doing the same, post problems encountered with my solutions and emphasize the non-stock custom work. Many areas of CB750 restorations are well documented on this forum need not be repeated (carb and tank cleaning, frozen brake caliper, etc).
History
Two years ago I bought a K4 and a K3 CB750 from dude out in the countryside for cheap. I had other project bikes in progress but the price was too good to pass up, so I bought them and stored the until this week.. The K4 turned over and had compression while the K3 was frozen. I spent an afternoon cleaning the carbs, tank, petcock, installing new battery, flushing the old oil and put the 4-4 exhaust from the K4 and fired her up. Tweaked it a bit and it idled and rode well, but the front brake caliper was frozen so I only rode a few miles on empty back roads to assess its condition. Solid motor, clean functional carbs, transmission crisp and smooth, crap brakes and tires and ugly as hell. A perfect candidate for a café rebuild. For the Honda purists, I am not destroying anything special, it is a Honda K4, not a Vincent, and there are thousands of these rotting away in barns, garages and backyards.
Life happened, several other bikes completed and sold, fell in love with a Norton, so I am finally making to the time to tear into this project. I have bought a mountain of new Honda OEM and aftermarket parts waiting for this bike. New rims, tires, spokes, all new cables, Fast from the Past rearsets, battery, pod filters, larger main jets etc.
Personal
I am a British bike junkie and build Honda cafes as my methadone and financial source to support my British habit. Like most everyone on this forum, I enjoy wrenching, building, restoring bikes and the pride and self-satisfaction of making something old beautiful again. It is my passion and hobby, but not my career. My day job is in the museum field and I am a trained archaeological conservator and work with high end art and priceless objects centuries and millenia old, so 30-50 year bikes are relatively easy and simple to work on. Free time is scarce for me and is spent either riding or restoring bikes to keep me sane and out of trouble. Cycle therapy.
Goals
My goal for this bike is to build a cafe racer in the true sense and spirit of the term: stripped down and fast with good handling to mimic the British track racing bikes of the 1950’s and 60’s. Appearance, though important, is secondary to function. There is more to a café racer than a bad black paint job, rearsets and an ugly seat on an ill running bike. I do crank up rebuilds on all my motors, complete rebuilds on my wheels (new bearings, spokes, rims and tires), meticulous electrical and carb work and work methodically, without shortcuts. The 74 K4 will be based heavily on two of my previous CB400F café builds; Honda Milano red tank, Manx seat, plain black side covers, black cylinder, clubmans, rearsets, 4 into 1 exhaust, rebuilt wheels etc. A strong and powerful girl in a sexy red dress. The K3 will have a strong Norton Manx and Triton influence (black hubs, front drum brake, black fenders, Manx seat, rearsets, clip-ons 5 gallon Manx tank, Dunstall and John Tickle style goodies etc). One of these two will have a GT550 4LS shoe front brake drum just like my Triton.
My first CB400f cafe build
Recent CB400f cafe
CB750 K4 as purchased in all its 1970’s chopperesque glory. Ugly, but got her running within an hour. A solid bike, but since it has been sitting for years I am going to build it from the crank up with all new gaskets, seals and replace the bearings as needed. Repaint cases, polish covers and rebuild carbs, paint frame, rebuild wheels etc, here we go…..
Finally, made the time to start this one. 6 uninterupted hours of bike time on a Friday and 8 hours on a Saturday-heaven! Stripped her to the frame, pulled the engine and pounded knee indents in the tank, first coats of filler and sanding.
I cleaned the exterior of the motor, pulled the carbs, soaked the cover screws in PB Blaster overnight and removed them with an impact driver. All but two screws came off easily. One screw on the breather cover got strippied and one on the stator was drilled and removed with a reverse easy out tool in a hand drill.
The stator and clutch covers were removed along with the carbs, clutch plates and basket, starter, oil pan and filters to lighten the motor before pulling it out of the frame. Two lifts and I got the beast out of the frame and on to a milk crate. It is still weighs more than I do.
Everything was cleaned, photographed, bagged and labeled. The frame and swing arm was an oily mess, but all that oil kept the rust at bay. Spiders were evicted.
Proper use of a self-service carwash....
Sump oil filter…. This is why I always strip my bikes down to the crank. You never know what has happened to your bike with the previous owners.
I have been waiting two years cut the rear hub out of the god awful, ugly 16’ Harley rim and fat tire. Why people insist on hobbling their machines with fat rear tires is beyond me. The hub will be highly polished, drilled with a few large holes with screens for ventilation, but will not have shotgun blast holes a la Carpy. I have a brand spanking new 18” DID rim, new spokes and Dunlop D404 waiting to surround the hub.
I picked up two Suzuki GT550 4LS front drum rakes recently. One, I bought a $200 parts bike to get it and the other I literally stole from someone on Craigslist who had no idea it was worth $300-400 unrestored (To thwart hate mail and possible theft charges I will not reveal the price). I collected all the necessary parts to install dual drilled front discs but I may go with the GT 4ls drum on this one.
The K4 tank was exceptionally clean and had one small dent, so I filled it, primered and painted it black. It is not pictured and I will save or sell it. For this project I used the tank from the K3. It was clean on the inside, but a Bondo queen on the outside and the tank badge holders were filled in. It was ugly and I had no problem smacking it with a hammer. I created a pattern outlining my knees, traced it on to the tank and pounded away with a rubber and plastic headed mallet. No problems, easy to do and both indents are symmetrical. The indents were filled with body filler and sanded twice. I layed down one guide coat of primer and sanded it to determine the high and low spots of the tank. I filled the lowspots, sanded again and it now has another guide coat. On more round of sanding and spot filling and then on to final prime, paint and clear.
I am busy this week and a have big pile of junk waiting for me this weekend. Frame to paint, tank to sand, prime, paint, clear and polish, motor to break down, rebuild, paint, polish...
Cannot wait, stay tuned…
