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Blood Sweat Tears and Grease => Projects => Cafe Racers => Topic started by: kittykatjaz on Apr 15, 2017, 21:58:33

Title: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Apr 15, 2017, 21:58:33
Hi Everyone,

What better way to introduce myself than with my little cafe racer build. I have been into bikes since a kid and always loved the GP bikes of the late 60's and 70's. Even owned and raced a few.

After years of wanting to I am undertaking a custom build of what was a basket case CB100 frame with CB125 engine I picked up a few months back. The bike is an old bucket racer with an engine  modded with a 62mm piston, XL head, custom crank and cam. Unfortunately the big end is blown and the engine incomplete.

The goal is to build a custom bike that is compliant with NSW AU registration without needing engineering by leaving the frame and running structure as original as possible and doing all the ancillaries within the Australian Design Rules to the year the bike was built.

I plan on making as much of the gear as possible using aluminium. It is either 5052 sheet, 6061 plate, 7075 round. So far I have made the seat/tail piece, combined rear guard and electrical tray which is hidden under the tail piece, fuel tank, rear sets and various other bits. I am just starting on rebuilding the engine.

The wheels I will rebuild using alloy valanced rims with stainless spokes.

I don't expect a powerhouse of a machine, I have a first gen CBR900 for that. This is a fun toy for scooting around the local area :)

Jaz
 
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Apr 15, 2017, 22:08:01
Here are some pics of the fuel tank construction. The fuel tank cap is a 2" Monza from the UK and tap is from an RGV250. It took a few extra welds to get pressure tight.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Apr 15, 2017, 22:13:57
The seat electrical tray and rear guard were made from the same material as the tank.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Apr 15, 2017, 22:27:04
Figuring out the rear sets was a tough one. I wanted to the mountings up high away from the centre stand mount instead of low like many of the others that have been done on the CB125. The pegs have to be folding for the use of a kick starter. The pegs and top supports are made from 7075 alloy which has a very high tensile strength. There is a lot of thinking required to make the first set of folding foot pegs that work well. I was surprised at level of geometry required.

I still have to make the gear lever and associated linkages and will wait until the engine is in the frame to do this.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: stroker crazy on Apr 15, 2017, 22:57:26
Welcome aboard kittykatjaz!

Brilliant start to your build thread; tank and seat etc. look real good and the footpegs leave me speechless.

Can't wait to see what you do with the motor!

Crazy
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: canyoncarver on Apr 15, 2017, 23:07:49
Really nice fab and welding work.  Looks like a fun build. 
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:09:07
The little tiddler is starting to take shape now. The engine is assembled, wheels done, controls connected and I am about half way through making the new alloy front guard. Everything that has been fabricated has been done in my little workshop and it has been an enjoyable experience. Once the front guard is finished I will start on the exhaust.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:25:12
The engine took a bit of work to get together. I had to buy a couple of parts engines to get all the missing bits of the gearbox, kick starter and all sorts of other parts. Then clean it all up and determine what to rebuild or replace. I replaced the big end and con rod. The crank halves were scored so I machined them and fitted thrust washers. The crank has been lightened somewhat when compared to an original. New 62mm piston kit sent from the UK which will make the engine close to 150cc. New timing chain and guides, new genuine seals, main bearings and lap the valves. Once all prepared then assembled. The head is ported though I have no idea what grind is on the cam. It could be standard but it looks like it has been welded and ground. Guess I will find out when it is started.

I fitted a new Mikuni VM28 flat slide carb. I also have a Dyna S ignition to go in.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: Luugo86 on Jul 01, 2017, 08:26:20
Those are some TiG-Tastic welds. Well done man. May I ask what guage sheet steel you used to form the petrol tank and seat ?
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:29:49
Those are some TiG-Tastic welds. Well done man. May I ask what guage sheet steel you used to form the petrol tank and seat ?
Thanks.

The alloy is 1.6mm thick 5052 grade.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:32:19
As the cylinder head is off an XL of some variety I had to move the upper engine mount and make a new bracket. Was a straight forward task.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:37:52
Wheels were fun. I purchased a couple of second hand valanced rims being 1.85x18 for the front and 2.15x18 for the rear. Also new stainless spokes and nipples. It took a bit to clean the rims and hubs up. Fitted new wheel bearings then laced the wheels up. To get them straight I also made the wheel truing stand.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: Luugo86 on Jul 01, 2017, 08:39:12
 Do you have any detail on how you welded in the fuel petcock bung on the tank?
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:42:20
The top triple clamp was a pain. I decided to machine off the original handlebar mounts and weld up the rear holes. I don't know what type of alloy was used in the casting but it was crap to weld. As soon as the torch lit up it just splattered everywhere. After mucking around with tig settings the best I could get was a barely passable result. I am not game enough to hit it again.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:49:24
Do you have any detail on how you welded in the fuel petcock bung on the tank?
Sure have.

I bought a second hand RGV250 petcock then machined a thick 6061 alloy plate drilled and tapped to match. I welded the plate to a small box section that sits as the lowest point of the tank. The weld is not pretty there but it is solid.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 08:58:06
Doing the rear brake cable setup took a bit of thought. I made the brackets, adjusters, clevis and cable. To make sure the cable is going to be safe I made a tool to birdcage the inner cable before soldering. All the local bike stores looked at me funny when trying to buy cable ferrules and nipples. Finally I had to order them in. I have also had to shorten the front brake cable and clutch cable using the same technique of birdcaging the inner cables and dipping in hot plumbers solder. 
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 01, 2017, 09:03:05
For the speedo I am fitting a Daytona Velona with an active pickup fitted to read from the front sprocket bolts. I welded an alloy block in the side cover then machined it to fit the active pickup. It has been machined to give the sensor 1.5mm clearance from the sprocket bolts.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: Luugo86 on Jul 01, 2017, 13:22:43
Thanks for the info on the fuel petcock man, I appreciate it. Was it difficult to weld that alloy block to the cast engine side cover? Those engine covers are really porous metals, just curious how it acted when you put an arc on it. You must have a pretty nice shop man lol.. all that machining.
 
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: jpmobius on Jul 01, 2017, 21:14:19
Some nice work there.  Especially like the eccentric peddle adjuster - often overlooked.  I often bore a hole axially through the threaded section of a stainless bolt and silver solder the cable to it.  Stronger than the cable itself, and makes a handy adjustment to the cable length when you don't want to have the adjustment at the housing as you have nicely done.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 02, 2017, 01:45:32
Thanks for the info on the fuel petcock man, I appreciate it. Was it difficult to weld that alloy block to the cast engine side cover? Those engine covers are really porous metals, just curious how it acted when you put an arc on it. You must have a pretty nice shop man lol.. all that machining.
Welding the side cover was not too bad as I was not worried about the looks of it. I hit it with a die grinder first, then stainless brush then acetone. The only bit that splattered was the lower part but I only needed enough weld to securely hold the block in.

My tools are good and equipment well setup but workshop is a cramped mess.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: der_nanno on Jul 02, 2017, 05:30:01
That's some nice milling work you do with that mini mill!
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 02, 2017, 20:41:47
Some nice work there.  Especially like the eccentric peddle adjuster - often overlooked.  I often bore a hole axially through the threaded section of a stainless bolt and silver solder the cable to it.  Stronger than the cable itself, and makes a handy adjustment to the cable length when you don't want to have the adjustment at the housing as you have nicely done.
That's a good idea.

The eccentric pedal adjuster was the tidiest way I could think of adjust the pedal height with as little work as possible.

Saw the thread on your RD. One beautiful Yammy!
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Jul 02, 2017, 20:52:38
That's some nice milling work you do with that mini mill!
Thanks

I would be lost without my mini mill and lathe. I have spent quite a bit of time setting the mill up and adding bracing to stiffen the whole setup. By far the best addition was digital readouts as they add a higher level of accuracy with ease. It is nice to be able to make two components that fit together perfectly without constant adjustments.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: der_nanno on Jul 03, 2017, 10:26:29
Couldn't agree more, I am running a "slightly" larger round-column RF-25, but even though bigger, the minimill with its dove-tailed spine is way superior. (I should have kept mine and converted it to a CNC-machine, but you know how it goes...)
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Aug 07, 2017, 21:36:36
it's getting close now to finishing the final dry assembly. Only a couple of things left then strip back down to finish all the parts off

Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: coyote13 on Aug 08, 2017, 13:00:29
She's a beauty, I'm in!
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Aug 11, 2017, 07:33:28
She Lives!!

Today I got my little racer running for the first time. After a quick couple of runs I took this short video.

The carb is a little rich just off idle but I won't both tuning until the air filter is fitted.

The gearing is quite high but she revs out nicely. Going to be one fun suburb blaster.

https://youtu.be/DUr1dEmUmN8 (https://youtu.be/DUr1dEmUmN8)





Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: canyoncarver on Aug 15, 2017, 12:42:41
Sounds great, that's gonna be a fun bike.   Now, about that FZR I saw in the video....
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Aug 19, 2017, 04:20:48
Sounds great, that's gonna be a fun bike.   Now, about that FZR I saw in the video....
It sure is going to be a fun little bike to scoot around on. The FZR you saw is actually an original first gen Honda CBR900 Fireblade. A huge lot of fun that one is!
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Aug 19, 2017, 04:30:47
Today I finished off connecting the Velona speedo with the pickup on the front sprocket bolts, connected the indicator and high beam instrument lights then tidied up all the welds on the seat tail piece including rounding everything off. Once last walk around with her running before stripping down to paint then final reassemble.


The last couple of days was spent making the pod air filter casing. It is a requirement for registration here in NSW Australia, no exposed pod air filters allowed.


https://youtu.be/KNdwBhkxdak (https://youtu.be/KNdwBhkxdak)
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: canyoncarver on Aug 21, 2017, 12:31:24
It sure is going to be a fun little bike to scoot around on. The FZR you saw is actually an original first gen Honda CBR900 Fireblade. A huge lot of fun that one is!

Ah, the quick glance had me fooled.  Great CBR too.   Your work has me wanting the benchtop style machining setup.  Great work on the little cafe!
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Sep 03, 2017, 03:35:26
My little racer has for the most part gone as far as I can go. All that is left is to make the seat pan and have it upholstered. I will make the pan tomorrow then off to the motor trimmers as it is the only thing I cannot do.


With luck it will be finished this week then off for a full check and if all goes well registration.


Out of all the aluminium work that I did the hardest part was the front guard. The tank has some ripples in it which are noticeable now as I decided to polish not paint. Still I am pleased considering this is the only fuel tank I have ever made.


Now just can't wait for rego so I can ride her.


Oh her name is Pirate Kitty!
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: stroker crazy on Sep 03, 2017, 05:58:09
Oh her name is Pirate Kitty!

Great name and logo!

I hope to see it out and about one day.

Crazy
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: coyote13 on Sep 08, 2017, 12:56:35
That intake turned out really well, it looks like it should have enough length to avoid any major tuning issues
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Sep 16, 2017, 05:42:24
That intake turned out really well, it looks like it should have enough length to avoid any major tuning issues
Its actually a pain to tune. I have been mucking around with it all day have found it easier tune with the foam uni filter pod straight on the back of the carb. I am going to order a couple of needles and selection of main jets and keep persisting.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Sep 16, 2017, 05:47:57
Well I have 250km's clocked up on Pirate Kitty and she is a treat. Such a nimble little girl on the bends and as light as a feather. The Mikuni VM28 tuning is close now, still a little rich on the top end of the mid range. Revs out and can reach 80 kph (50mph) in second gear. Little sluggish at low revs but I can live with that.
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: Luugo86 on Sep 16, 2017, 12:07:19
That is a slick little bike man. I love the metal work.. did you do it yourself?
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: coyote13 on Sep 16, 2017, 15:50:00
The Mikuni VM28 tuning is close now

I guess I assumed you were running the stock carb, you should be ok with just a filter directly on that VM.  Sounds like you've got it pretty close as-is though
Title: Re: CB100/125 Big Bore Old Skool Cafe Road Racer Build
Post by: kittykatjaz on Sep 17, 2017, 01:04:13
That is a slick little bike man. I love the metal work.. did you do it yourself?
Thanks and yes, did everything except the seat upholstery. I chose to make a lot of parts instead of purchasing so that way they would fit perfectly and suit the idea of what I wanted.