A '79 Honda CB, and me

Well, I decided to something stupid and for scrap price bought a non running '79 Honda CB 125. 

Has a title and all the parts are there, was parked for a bad battery. Previous owner removed the carb to clean it up and stopped. Has good compression, and 3xxx miles so what the hell. 

My friend was moving today, so we used the U Haul (with a ramp, hell yeah) and brought it to my mothers house, where it'll share the garage with my '75 Oldsmobile. 

Its red. Its cool, I'll post pics later. What have I done.

Why is that stupid? I had a CB 100 years ago. Old Hondas are great. 

In reply to Snowdoggie :

Well I've never owned a bike in my life. Sorry should have clarified! Lol.

Good time to learn i guess!

You can get new carbs on e-bay. 

In reply to Snowdoggie :

Thanks, I had started to look, but it seems the ones online have a different mounting style than mine. I'll post a picture and if you would, maybe shine some light on the subject, I'd really appreciate it 

Post some pictures. I'm sure we can help you sort out the carb issue.

I picked up a 1975 CB125S earlier this year. A bit of messing about had it running within a day and then I tore it down to the frame. I need to rebuild the wheels before it goes back together, so that's where I'm stalled. Now that race season is over it's time to work. 

Sweet bike Seth! And thank you.

Putting the U haul to good use

Box 'o Stuff

And my carb confusion!

I belive the left is the factory carb, the right is brand new. Where it would mount to the manifold is my conundrum. Totally different, and all I see online is the new carbs style.

Am I missing something here? Thanks again fellas.

Amazon has one listed made by Aitook for $19. Probably a Chinese knockoff. I know a lot of Chinese engines are copied from Honda. Not sure of the quality but for less than $20 it might be worth a shot. I was looking at one for mt CT 90.

Here's the factory shop manual for a CB125S, it will help you figure things out.  https://www.manualslib.com/manual/1049271/Honda-Cb125s.html

In reply to stuart in mn :

Wow great link, thanks!!!

I guess my big question, that'll I go outside and figure out eventually lol, is if the replacement carb that has a flange, eliminates the stock "boot" style of the other carb? 

Thats all I can find online is the flanged bolt on style.

I took a few pictures from my engine and the Clymer manual I have. This should be the setup on your bike with the clamp type boot. They didn't use this on very many years/models it seems. 

The next two pictures are the diagram from the book and the picture of my motor showing the setup that would fit the newer carb that you have. 

To convert you'd have to replace the studs and find the bits and pieces. Alternatively you may be able to use an XR100 intake boot, but I need to put out my other XR100 motor to check that. It would probably be worth converting as there are a million cheap carbs that use this bolt pattern. 

Edit: did a quick check and the XR100 boot won't work, the studs on the head are in a different orientation. 

My first bike was a 75 cb360 they I slowly made into a cafe bike. I legit put 8k a year on it for years. I miss that bike. 

Thanks Seth, I appreciate you checking on all that!

Confirms my suspicions then, I'll have to get creative here.

Well I used the top end of the stock carb, swapped everything else over from a replacement Japanese carb, and put it on.

Battery is dead, to the store I go!

could cut the ears off that flange, grind to fit, remove the o-ring and use the origional boot style mount.  

In reply to TGMF :

I thought about it but the way the boot goes over, i wouldn't have enough material on the newer flanged style to seal to, it swoops down right behind the flange. I think this will work just fine, I hope lol.

Didn't get a huge amount done as I took a break for a belated birthday lunch with some family today, but that was a worthwhile break!

Well battery is charging up, the new one that is, neighbor had an older 6V in the garage i hooked up just to see what happened. Not much of a spark from it, but the horn worked a bit and I got a faint dim light. Only had 4.2V across the terminals though, so couldn't test much. 

Tomorrow I'll put the new battery on, and see what we can make happen. The wiring is uh, interesting. Thanks to the info from Stuart Seth and others, I was able to find a wiring diagram and im going to trace and check everything before I put it all back together. Worst case Ontario I can order a new harness from somewhere in the Orient, as they all seem to come from the far end of the world, where these bikes have a massive following. Quite cool to see how necessity becomes the mother of invention in keeping 40+ year old bikes as daily transportation in some places, very neat.

Does the 1979 still have points or had they moved to CDI by then? 

And if you don't have one yet, a Vessel Impacta #2 screwdriver will help you immeasurably when trying to move screws that have been in place for 40 years without mangling them. 

In reply to mazdeuce - Seth :

Still points in '79, and 6V. Not sure when the changeover happened to CDI and then 12V?

Yes! I recently bought one of those, what a great tool!

Ok, so the neat thing about the electrical system is these is that you don't really need it. The only important bits to make things run are that the stator makes electricity, that electricity goes to the coil. The signal part of the coil has the condenser and points on it, and the plug wire part goes to the plug. So that's it. If you get power to the coil, and the points work, it'll make spark and you can ignore the whole rest of the wiring system until after it runs. 

This is a simplification of course because in general you need an off switch so you can turn it off and you need the grounds to be good, but really, you can run the bike on about 18 inches of wire total. It's magic in it's simplicity. 

mazdeuce - Seth said:

And if you don't have one yet, a Vessel Impacta #2 screwdriver will help you immeasurably when trying to move screws that have been in place for 40 years without mangling them. 

As I learned on a CB160, he's not kidding. I would say an impact screwdriver is a necessity, and turns breaking those screws loose from a trial/impossibility to easy peasy. IIRC I replaced them with Allen head fasteners.

Woo hoo! It runs!

Bypassed the ignition wiring, because its a mess, but hooked up the fuel lines, 5 kicks and it fired up. Seems to fire on the first kick now every time. Sweet! 

Lots more to do but this is encouraging 

My checklist for resurrecting things:

Make it run. 

Make it drive. 

Make it awesome. 

Well thanks again for the help so far, truly appreciated.

Seems like the battery is charging. Started at 5.99V and after a little ride around, it was at 6.43V. It's idling very high, but I think the throttle spring is bound up.

I found the original ignition switch in a box, so I think I'll use that and make my own "harness" one system at a time, just to get it safe to ride for now. Next step is servicing everything and we'll go from there!

They're absurdly durable, especially with modern synthetic four stroke oil. Remember to use the bike oil since it's a wet clutch. You probably know that but I still talk to people every now and again who don't. 

How old are your tires? It's pretty common to pull these out of a shed and have tires that are decades old. Tires really are even more of a safety thing on bikes than on cars. Other than that, send it. Put some miles on. When I start to put mine back together again I'm sure I'll have questions to ask you.