CB750 Cafe Ricer

One week after purchase:

Pretty much ready to ride

Now I really want to find an old bike to work on...

Gorgeous! Man, that looks like so much fun...

Pretty, looks like a blast to work on old bikes.

I stopped by the local vintage bike shop again today and picked up some fork seals, fork oil and paid for the black bars that are on the bike (they loaned me a few bars last time to "try on"...nice guy.) Total cost $50 so the new total is $940.91

I may wait a week or two before I tear into the forks. I want to ride it a bit first.

I rode it to work today, and took it to show the old owner at lunch. Put the first scratch in the paint thanks to a rivet on my pants.

So far it's turning out pretty close to the Photoshop image:

Photoshop:

Reality:

What do you all think about adding a flyscreen?

Here's what it looks like in isometric (another thruxton style piece):

I like the looks without the screen, but I'm sure it helps make the ride more enjoyable.

The bike came out great!, +1 for flyscreen. What about doing something with the goofy tail light. The stock bracket seems too big.

bgkast wrote: About 11 years ago (before cafe racers were hip....

....and about 35 years AFTER cafe racers were hip the FIRST TIME...

Nice work on the bikes! Takes me back to 1970-75 when we were doing this to 2 stroke Kawasaki triples - the green screaming meanies....

In reply to MichaelYount:

Good point. I would love a big two stroke.

I got some screws to mount the tank badges. Cost: 27 cents. New Total Spent: $941.18

Are you familiar with this CB 750 build? Only 19 installments to the build, so don't blame me if you lose an hour or three.

https://www.youtube.com/watch?v=MkHJuU01-Wk

Thanks for the link, I hadn't seen that. Goodbye productivity!

My fork rebuild has just got more expensive and I've broken the $1000 mark.

After buying the fork seals last weekend I noticed that one of the rubber dust covers was cracked, so I decided to switch to more British looking gators to the tune of $24.

While researching how to rebuild these old dampening tube forks I came across a way to modernize them and give a better ride and handling: the cartridge emulator:

Dampening tube forks work by forcing oil through an orifice. The issue is that the orifice is a fixed size. On small bumps the volume of oil moving is low, and it has an easy time passing through the orifice. To give good dampening you want a small orifice for this scenario. The problem is when you hit a large bump. The oil all needs to move through the orifice quickly or else the fork will not be able to compress and will transmit a large shock. This requires a large orifice.

Since you can only have one size of orifice this leads to a comprise: the orifice is too large for small bumps or small loads like breaking, giving a squishy, pogo stick ride and too small for large impacts giving a harsh ride. Enter the emulator...

The emulator sits on top of the damper rod between the rod and the spring. It still uses a small hole for small loads, but for large loads a larger spring loaded valve can open to pass larger volumes of oil without giving a harsh ride. This allows the small holes to be properly small giving a better ride on normal roads and preventing the nose from diving when you hit the brakes. The spring loaded valve is adjustable for fine tuning. The old medium size orifices are drilled out so they no longer function.

New Total: $1033.60

I forgot that I hadn't properly bolted the seat on because I didn't have long enough bolts. $2.10 at the hardware store for that. As I was looking for an illusive 10mm wrench to put them on I found a set of original Honda wrenches that I bought a few years ago at a garage sale for $0.50, so I added them to the bike.

New total: $1,036.20

NOHOME wrote: Are you familiar with this CB 750 build? Only 19 installments to the build, so don't blame me if you lose an hour or three. https://www.youtube.com/watch?v=MkHJuU01-Wk

Thanks for that, man. I am quite enjoying it-vicarious living and all.

I rode it to work yesterday. On the way home I started loosing power, so I flipped the petcock over to reserve...and kept loosing power. I tried nursing it to a friend's house, but it died and I had to push it the last few hundred feet.

Turns out even Hondas need gas...

The tube that stops the petcock from drawing the whole tank dry when on the "on" setting is missing.

I like the flyscreen. And 2 smoke street bikes.

So are you happy with the emulators for the front forks. Seen them advertised, but I wanted to know if you really feel a difference.

Awesome!

I rebuilt a '74 a few years back. Had more than one person think it was a Norton Commando (From a distance).

I got rid of that huge rear fender/taillight assembly and replaced all the turn signal with the small, modern ones off a Yamaha FZR. I drew up a seat and had a local custom upholsterer stitch it up for me. Modeled it after the sport bikes of the day. It sure was fun kick starting it while all the other guys were electric-only.

My brother had a Ninja 1,000 at the time and we switched a time or two! Night and day

In reply to fanfoy:

I'll let you know how the emulators work in a few days. They arrived yesterday and I tore into the front end.

I started by cobbling together a prop to keep the front end in the air out of some scrap wood. I then took off the wheel and pulled one of the fork tubes. Surprisingly after loosing the clamp bolts they almost fell out! I figured they would fight me.

With one tube off I set about tearing it apart following instructions in this handy video: http://youtu.be/pV5ZkIBtrns

Other than the seal being a bear to get out, it all went smoothly.

My damper tube needed some extra modifications to work with the emulator. The large top end on mine was made from two pieces held together with a roll pin. Others have said that they have had success just cutting out the center of the pin so that it doesn't interfere with the nut on the bottom of the emulator, but that didn't seem like a great solution to me, so I decided to tack weld the top piece to the tube. I drove out the pin, but even with it out I could not get the top piece to come off. I tried cleaning it with solvent and a brush, but my first tack weld was still very contaminated from the oil between the two pieces. I resorted to using a propane torch to burn out as much oil as I could. The welds still ended up with a little bit of pitting, but 6 of them should be sufficient. I also welded one of the small rebound holes near the middle of the tube shut and drilled out the compression holes at the bottom of the tube and added two more sets of holes per the emulator instructions. I also had to open up the inside diameter of the top of the tube just a little with a die grinder to allow the emulator to fit well.

Tonight I hope to get this fork put back together, and hopefully finish the other one too.

The new seal was just as hard to install as the old one was to get out, and the top got a bit chewed up in the installation process. The sealing surface still looks OK, but I think I will pick up a new set and re-do it anyway...

I've been looking at cartridge emulators for my old Suzuki GS1000, and some high end shocks.

I got the forks back together and ready to put back on the bike. Not many photos due to being covered in fork oil. When I picked up a replacement seal at the local bike shop the old timer that runs it told me the trick to driving in the seals: use the old ones upside-down as a driver. Once the new seal is down low enough put the snap ring in over the top and use it to drive the seal down until the snap ring engages the groove. This worked well on the first seal, but when I was driving the second seal in it suddenly went in easy before I had the snap ring in place and went in crooked and too far on one side. I put the snap ring in place and finished driving the side that was still too high, then gently used a wide screwdriver to pry the low side back up.

The tops of the forks where they are hidden by the headlight ears were quite pitted, so I cleaned them up and hit them with some cold-galvanizing primer to try to keep them from getting worse.

Tomorrow I will mount them back on the bike and test out the emulators.

I test-rode the bike into work today.

The ride is better, but it's not a huge difference. The emulators definitely make the ride over sharp bumps smoother; now I feel them in my arse instead of my arms. The ride also feels stiffer and lest "squishy" on little bumps letting you feel the road better (this could be good or bad depending on what kind of ride you want). The emulates also increased the pre-load of the main springs by 3/4" or so which also contributes to the stiffer feel. The front end still dives some under braking, but it does it in a more gradual manner. Overall I am happy with the improvements, I could probably make the feel even better by tuning the pre-load in the springs, emulator springs and fork oil weight, but I will save that for later.

Bottom line: Are the emulators worth adding while you are rebuilding the forks? Definitely. Would I tear apart a good set of forks to add them? Probably not.

I like the look of the gators on the forks.

I forgot to update the budget with my last post. I had to buy a replacement spring for the swinging front caliper at $2, and a over-sized bolt for the brake master cylinder at $0.69. I also sold the extra handlebars I this morning for $40.

Previous total: $1,036.20

Spring: $2.00

Bolt: $.69

Bar sale: -$40.00

New Total: $998.89

Do you guys think this thing would be eligible for pit-bike of the month?