C-200 cafe'....My project bike.....

[66Sprint]

Well, I ordered the 125 cc engine from Hooper today....Once it gets here I can get this project rolling!

I hope I'm not getting overly ambitious....Hoping to get a 60 to 65MPH top end out of the little girl...... :wink:

[FastDoc]

With these small displacement bikes top speed is more of a factor on pilot weight than engine size:-)

[Weldangrind]

On a little bike like that, I think 60mph is attainable. It might take a full tuck, though.

[66Sprint]

Fortunately I'm a runt....5'7" and 145 lbs.....I might get it to those speeds.....
HOWEVER, in my next few posts, I'll discribe mods I've made to the suspension and brakes (anticipating a larger engine, AND somewhat for that "vintage racer" look......)
Since the Honda CT series (70 and 90cc) and many "early, step-through" 50's had the pressed metal/ internal shock/leading link forks, some of these mods may interest other members....
Mods include easy preloading the shock assemblies (to prevent the dreaded fork dive) and provide a more modern "feeling" suspension....

Stay tuned......

[Weldangrind]

I'm most interested, thank you. Once the dreaded bathroom reno is done, I'll be back on my YB100 to China 110 project.

[66Sprint]

Since this is a project log of sorts, let's start with the bike as I got it.....



I knew stock wouldn't do, so started researching period factory race bikes in their "streetable" configurations, and fell absolutely in LOVE with this one...



Similar pressed frame, similar leading-link front end, massive brakes and most importantly, it didn't look like every other cafe/race bike on the road....
So I started making a list of necessary changes to the bike I had to end up with one that while suggesting Honda's "racer" styling, would still be within the limits of what I had to work with, ( NO non-reversable changes) and be a creation unique to me.......

First on the agenda, a better front brake and improvements to the suspension that would allow its use without increasing the "pogo" the leading link forks are notorious for.....NOT an easy task.....

Originally, I tried a CB200 disc front wheel carrying a GY6 (smaller) rotor and using the scooter's hydraulic brakes....This worked (too well) but didn't "look" appropriate......



I eventually settled on an 18" CB350 front drum wheel (replacing the stock 17" wheel with tiny drum) but again, the front end reacted too strongly......



A major part of this problem being the "soft" front suspension (shocks) combined with excessive wear of the bushes in the links' pivoting joints...

How I approached these problems next post...... :wink:

[FastDoc]

I much prefer the look of the drum brake on that bike.

I kinda like the art deco style of the original fender, although the redesign is way cooler. 8)

I had a Moto Guzzi moped when I was a kid that had leading link front suspension like that. It rode smooth until you hit the brakes, in which case it would stiffen a lot and raise the front end. Worked OK but takes getting used to. :?

I respect and appreciate your combining Chinese and original parts in your project. Nice to see soemone who is not a slave to originality, but respects the design of the period.

This is gonna be a great project to follow. :P

[FastDoc]

BTW is your garaged tiled or are you working in your kitchen?

[66Sprint]

Ya got me....Pix were taken the kitchen....LMAO!...

[FastDoc]

You must be single.

[66Sprint]

Nope...The wife loves bikes too!......

But, let's get back to problem solving.....Suspension:
Due to physical size limitations within the fork body, heavier springs could not be easily fitted to the shock bodies (damping units), but installing large, thick, stainless steel washers allowed me to get a dual benefit....
#1 the assemblies are slightly physically longer, meaning there was LESS motion to the links before they came against the bottom rubber stops ( Less downward motion translates to less "lift" when the brakes are applied)
#2 The washers simultaneously "pre-load" the springs giving an overall stiffer suspension.....

This pic shows the modified top shock with one washer vs the stock assembly...Ultimately two washers spaced everything better for a rider around 150 lbs....



Replacing the pivot bolts, collars and bushings (I had bronze bushes turned) to eliminate any "slop" from wear, signifigantly improved the action of the links and yielded a smoother ride.....

NOW to the "hard" part..... Mounting an 18" wheel with a large hub and a 15mm axle size in between forks and links designed for a small, narrow hub with a 12mm axle size..... and the new DLS linkage that inevitably would find NO room for clearance as the links rocked upwards from any roadway irregularity.....
The solution, of course, was to cut away any interfering areas of the stamped/pressed metal forks, then rebuild them with adequate clearance to restore their structural integrity......Easier said than done, but I was successful although it also involved several other minor alterations to the existing parts to maintain that clearance........Some pics of the steps follow......

Original fork bottom area.....


Cut away and clearanced.....




Cardboard template for structural repair.....



Primered fabbed piece ready to weld on.....



Finished modified fork bottom.....



..

[66Sprint]

Mostly, I went into some detail in my previous post and pics to (hopefully) show that ANY problems can usually be overcome IF one takes the time and solves it in carefully considered steps ....None of what I did was "rocket science", just a series of overcoming small problems one at a time......
These are strikingly simple machines, but that does not mean one should make changes without considering the structural, mechanical, and safety aspects of the change.....

If this inspires someone to attempt a mod or change they want, but are unsure of their ability to do, and they are willing to proceed within those guidelines and/or ask questions about the mods when they re in doubt, then I have done my REAL job.....

[Weldangrind]

I respect your problem solving skills.

As much as I like the stock front end, did you consider a swap to a more conventional set of forks?

[66Sprint]

Yes, I even had an early CB100/CB125 drum front end offered for my use....It fits perfectly and almost looks to be a stock configuration on this bike as well, but I had several of the original type forks (actually from CT 90's).....Since they presented the bigger challenge to modify, and somewhat had (to my eyes) a more correct "vintage" essence about them, I went with them.....
IF I were building a non-streetable version bike, (racer replica) I probably would have run the tube forks (preferably an externally sprung version).....It certainly would have required less effort to mount the larger drummed wheel.......

[Weldangrind]

The forks on my YB have tube covers that I had to remove to slide the forks out of the triples. Once I removed the covers, the springs were exposed. The covers aren't going back on.