1974 Honda CB125s cafe build

[kamikazi117]

i bought this little 125 about 2 months ago restored it and i'm not really happy with how it turned out, so now i'm going to turn it into a cafe This is my first motorcycle but i've been riding motox for years...

Here's how it stands at the moment:

My goal is to completely rebuild the motor as for some reason my cam gear keeps getting destroyed, the first time was after i got the motor running i was driving, down shifted, rpms were at about 7k and then the motor just stopped running, got it home found out that it had no compression, pulled the timing cover off to find that the gear had no teeth left, pulled the motor, as i was rebuilding it i found that the intake valve was bent so i bought another head off ebay regasketed the motor, painted the bike, rode it for about 50 miles and then the same thing happened.... I'm thinking that theres an oil galley plugged?

I don't like the way the colors look so I'm going to redo all of that

a couple questions i have before i pull the trigger on a couple buys is that:
1. does a xr200 top end bolt up to the 125s bottom end? i've found some people asking the same question but theres a lot of mix matched answers and no one really gets to the real answer
2. If so what work is needed if anyone knows?
3. if the xr200 is a bunch of work then i'm just going to stick with 125 parts, so is there any difference in the 125's split top head vs' the solid top?

 

[kamikazi117]

first thing i'm doing is converting this bad boy to 12v
so far what i know that i need is a
1. honda cb350 stator (the only thing you need to modify is switching over the square plug from the 125s, the cb350 is a round connector. just cut n splice.)
2. a 4 wire 12v rectifier. I'm just going to order a used one from a cb350
3. update all the light bulbs to 12v
4. 12v turn signal relay
5. 12v battery ( i'm ordering a ballistic 4 cell battery 80 cca only $45 and i can put it anywhere, its about the size of the ignition coil)

Does the ignition coil have to be changed? and is there anything else i may be missing?

 

[kamikazi117]

Does anyone happen to know what this wheel setup is?

 

[bojica]

Re: 1974 Honda CB125s cafe build

not sure, but I like it. I wonder if I can run the same setup on my 200 if we can figure it out

 

[kamikazi117]

Here's how my bike sits as of today:

I've been messing around trying to decide on how i want it to turn out, i'm not planning on racing my motorcycle. I'm just more less trying to get it to look like a cafe and have a little better top speed. I'm planning on running 16/35 gearing and swapping the rear wheel out for an 18 incher. people are doing 75 with that set up.

you can see all the metal shards in the oil filter from the timing gear going out:

Timing Gear:

And bent exhaust vavle:

 

[kamikazi117]

Does anyone know whats really needed for an xr200 top end swap?

So far what i know you need is the xr200 cylinder jug, the xr200 complete head, xr200 camchain tensioner, the xr 200 piston. I know that the cb125's crankcase has to be bored out to fit the jug and the jug may need to have the bottom shaved?

I'm a little confused about the crankshafts. i've read that there's an 8mm difference in stroke.
I don't know what year xr200 crankshafts will work in my 125s casing. i know that the bearings have to be switched out. i may be missing something?

 

[kamikazi117]

anyone by chance know the recommended head stud torque down for the xr200?

 

[Kanticoy]

Re: 1974 Honda CB125s cafe build

Isn't the xr200 a different stroke than the 125m i know the grudgeon pins are different sizes.

 

[kamikazi117]

i'm planning on using everything from an xr200 for the top end. crankshaft, connecting rod, wrist pin, piston, cylinder, and head? I don't think the grudgeon pin (wrist pin) will matter in that case?
From what i've read up on, the xr200 has an 8mm longer stroke

 

[kamikazi117]

So im going to try and get this project going again.

anyone have any information on an xr200 top end swap.
i've found tons of bikes with the conversion, but no definitive information.

 

[surffly]

http://www.oldrice.com/xl_page.htm

Read the millions of articles there and search they forum

Not 100% sure about using the XR crank as well in the build. When I was going to run the XR head I was limited to a CC class so didnt go with the stroke.

Powroll still makes some killer parts for these motors including cranks, but I assume you are trying to piece this together with OEM parts to save money.

 

[kamikazi117]

yea, i would like to keep this project on the cheaper side. In case something goes wrong I can afford replacement parts.

 

[kamikazi117]

anybody know anything about extending the swing arm? Best way that i've seen it done is with a honda gl200 swing arm, but i cant seem to source one. I cant even find a complete bike for sale.