XL/CB100 cafe - "Mini-Mono"

[eyhonda]

This is repeat of my introduction but it's the start:

I wanted to also say that this is an awesome forum, especially for cafe bikes! A huge one-stop of info, wisdom and inspiration! Keep it going everyone! A lot of cool little bikes here, which I like a lot! So simple and minimal!

My two sons are starting to build their first street bikes - CB100's. So, I decided to build one along with them and we can ride together. I will use an XL100 frame as my base over the CB100 frame. It has seat tubes located lower to weld some rearset brackets, 2" longer swingarm and a seat hoop. I picked the 100 frame over the 125 frame because it is similar to the Dream CB50r (48" wheelbase), which I will loosely use as design goal. It can accept all the same vertical engines as the CB100 frame.

As of now, I've just been collecting parts and the first stage will be to build the rolling chassis. So far, I have the following parts:
1. XL100 frame and swingarm; trimming in progress

2. XR185 steering stem; lower clamp is double pinch bolts, aluminum and removable. Longer stem and new roller bearings.

3. CL175 31mm forks

4. CB100 rear hub and CL175 front hub (160mm drum, drilled 1.25" holes)

5. 18"x1.40 (WM0) alloy rims, non-flanged, front & rear.

6. Durgam rearsets. Will use a CBR shift linkage & MR175 rear brake cable (rather than rod)
7. Rearset brackes: exhaust brackets from a CM185

8. CB100 bottom end with CB125 top end.

Still looking for some good shocks and will use 31mm clip-ons from Perrault or Woodcraft. Not sure yet on a tank and seat. Will probably change my mind a few times. I'll need to build it up first to get a visual and decide later. But probably for a seat, something upholstered on the stock trimmed pan with a bump on the back and for a tank something long, slender and small. I want to have the impression it is a small skinny bike. In fact, I'll probably name it Skinny!

Eric

 

[Mark in Seattle]

Re: "Skinny" XL100 cafe build

Hey E,
Looks like a good project, love that name, Skinny! There are a couple of us who've built XLs, my build link is in my signature and check out Rev's XL100 "Minimus", which was featured on Pipeburn, its wild. Have fun!
Mark

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Hey thanks! Yeah, I saw the XL100 Minimus bike after I did a search for similar bikes. Mine will actually be more CB than XL. It's based on the XL frame only.

Cool bike project you built. I like the bar design and how the seat pad matched the pattern.

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Today, I started to plate the spokes. Using the plating solution from Caswell and a decent variable power supply, I went at it. It comes out a little dull and rough. I finish it with some buffing using steel wool. Fun stuff!

 

[ffjmoore]

Re: "Skinny" XL100 cafe build

Looks good. Ill follow along.. I just finished a CB125.

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Cool, thanks! I like your build. Do you have a build list? I may use similar parts. I think you used Michelin Gazelles. I might try the Irc nr53 tires.

 

[ffjmoore]

Re: "Skinny" XL100 cafe build

If there are any parts on that bike you want i can tell you where i got them but i dont have a list.

 

[VonYinzer]

Re: "Skinny" XL100 cafe build

Cool. Signing up!

 

[eyhonda]

Re: "Skinny" XL100 cafe build

OK, thanks FF. I will let you know as I need the parts.

I found a parts bike, essentially a roller with a complete motor. I buy it up for my son and negotiate the motor for myself. He'll take the easy route and just buy a running motor. This one has been in the rain for awhile. But I turn the flywheel and it turns (only half a stroke tho)! I then open it up and voila - rusty pudding on top of the piston. It's missing the oil filter screen and cap at the bottom. I'm thinking this is what saved the bottom end. It's in good condition with no rust! Even the crank bearings. Either the rain stopped on top of the "pudding" or the rain drained away from the bottom.

The head has busted rocker. I plan on putting a cb125 top end. The cases have to be bored to accept the bigger barrel. But instead I get cb125 cases, including a good cylinder. I have an xl125 head free from a friend. I hope the gears will swap over, fingers crossed. I will just sell the rest of the parts.

I know that the best way to start all this is to buy a complete bike. This time I wanted to try the other route - buy it piece by piece. I local breaker already had the frame and swingarm. Also, it's a great place to pick up pieces cheap (no shipping) and measure parts for compatability (big plus). Also, this way, I can pick each part carefully instead of just making whatever I have work. That's why you see all the parts I have is from different bikes. I research what I believe is the best part for my application and budget.

As far as swingarm bushings go, has anyone with the small bikes (100-125) tried to improve the swingarm pivot? I will be getting new bushings and I will try to get someone to lathe up some bronze bushings and collars (or reuse the oems by removing the rubber). I know it's a small bike and it may or may not make much difference but I want to have a good foundation. A rubbery feeling swingarm pivot will make the ride feel too 'vintage' (hinge in the middle feeling). I'm improving every other part (tapered bearings including). So why not?! The next size up bikes have solid bushings and collars (160, 175, 200, 350). But they use 14mm pivots and we have to make due with 12mm parts.

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Hey FF:

What ignition did you use? The site doesn't call out specifically for a cb125. Does the cb450 fit? Any more details on it? How does the advance work? If it is still mechanical, then it must be still using the stock rotor with the weights on it. I was thinking to design something similar myself but still using the points as the trigger instead of the Hall Effect. I'm thinking they used a custom rotor with a magnet on it. Post a pic of the rotor detail.

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Today, I got my NOS Redwing shocks (dual rate) and Woodcraft clip-ons. A few nuts & bolts later and she's on the stands! I threw on the cases so I can get an idea where the shift rod will need to be. The fork lowers are getting prepped. This is my dry fit stage. I need to know where to weld the rearset brackets. There will likely be other brackets needed too [cable stops, battery holder, exhaust bracket, etc]. I researched different ergos of sportbikes. So, I have an idea where to place the bars, pegs and seat.

From here out, it will slow down. Holidays coming! I will build this one slowly. For me, that's about 5-6 months. I have a daily rider (Lucille, the Monster). So, I'm not in a rush to finish it. I'll likely beat my boys to a finished bike anyway.

 

[ffjmoore]

Re: "Skinny" XL100 cafe build

On my blue 125 i used stock points but on my red CL i used the pamco, it uses the stock advancer with a new rotor that has magnets in it.

 

[eyhonda]

Re: "Skinny" XL100 cafe build

...it uses the stock advancer with a new rotor that has magnets in it.

Ok, that's what I thought about the rotor. Which version did you order? You mentioned something about your application being experimental. Did they make a different version or does it just bolt on without mods? I think it is the cb450 ignition. They should update their site to show what bikes it fits. I think it will even fit a 175 twin as the rotor diameter is the same.

I was considering the Pertronix ignition but it has a locked advance and will be hard to start. That's a good price for that ignition though. I will still try to design one on my own just for the fun of it. I'm an electrical engineer by day. So, I will also make other electronic stuff (LED flashing tail light, turns, new wiring harness). If I really get inspired, I may build a fully programmable, micro controlled ignition that has a custom curve with a throttle input (load sensing).

BTW FF, you might want to check your sig. The last link goes somewhere else.

 

[ffjmoore]

Re: "Skinny" XL100 cafe build

Mine was experimental. He had not built one for a 125 before so i tested it on mine and it is still working great. It uses the basic parts that all the other units use but is configured so that it will fit in the 125. Just email him and tell him you want one for you 125. Ill fix my my sig. Thanks

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Wow, it's been a month already?!

Anyway, I got a couple things done in the last two weekends.

First, I replated the spokes. I wasn't so happy with the first attempt. I added a solution heater and upped the plating time to 30 minutes. Also, I made a holder from a wire hanger to do 18 spokes at a time. The current was up over 2 amps and the power supply got pretty warm!

The parts come out with a very dull silver finish. So, I brighten it up with fine steel wool. I've also plated most of the other hardware related to mounting the wheels, axles and brakes.


Then, I finished polishing the hubs and brake plates.

Lastly, I was able to lace and true the front rim:

Makeshift truing stand using a swingarm:

Taping strategy prior to placing the rim:

The rear is laced and will be trued in the next week or so:

The bearings are either new or re-packed. I repacked the old bearings if they spun true.

Finally, I got a rare Honda tank from the UK! It is from the 70-78 Honda SS50, not available here in the states.

Very cafe looking - narrow and long! Expensive to ship from the UK! It was worth it since it is hard to find, especially in the US. I can't wait to see it in person and on my bike! I'll likely repaint it. It needs a few dents fixed as well. Not sure of the color yet.

 

[ffjmoore]

Re: "Skinny" XL100 cafe build

pictures are not working for me.

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Ok, I think I fixed the links. LMK.

 

[Erskine]

Re: "Skinny" XL100 cafe build

I'm enjoying following your build. Those SS50 tanks are getting rare here in the UK now. I looking forward to seeing it on the frame for proportion. And seeing how you decide to mount the rear sets.

 

[eyhonda]

Re: "Skinny" XL100 cafe build

Cool, thanks! Yeah, I'm glad I stumbled on that tank. I was researching what tank to put and none of the US models came close to what I was looking for. Maybe the S90 but I don't like the chrome side panels. I should get the tank (and tires) next week. I'll mock up the rolling chassis with the tank next week or so. At least, I'll throw up a pic with the frame, front end and tank.

Currently, I just ordered a set of Bridgestone BT39ss tires (from Dream CB50r). I was going to get the IRC NR53 tires but they are backordered. Besides that, the Bridgestones are a more serious tire that will handle better.

Also, I am working on replacing the mushy rubber swingarm bushings. I found a set of bronze bushings from ASB and will be reusing the stock collars. I'll probably need to do some machining for the collar to fit perfect in the bushing. It's about .25mm bigger than the 16mm ID hole. Hopefully the bushing will press neatly into the swingarm.

I also still need to clean up the cutoff brackets on the frame and swingarm. Slowly but surely.

As far as the rearset bracket placement, I'm estimating 17.5" of legroom (distance to seat) and 13" from the ground, assuming I get 30.5" seat height. I'll get a better idea when I mount the tires and get to a rolling chassis. Then, I have to assume the seat thickness since I'm way far from that stage. At least the brackets will provide two mounting points, with a possible third hole drilled in the bracket, for flexibility in the peg placement.

 

[eyhonda]

Re: XL100 cafe build - renamed "Mini-mono"

I decided to rename my project. I don't think it will really live up to it's former name "Skinny". Brads Special is way skinnier! My frame is already 8" wide. So, in the same vein as Ducati's Supermono, I've decided on Mini-mono. I want it to have a racy tail up/front end down stance. Not too wild, just a nice cool rake to it.

BTW, how do I change the main topic?