Topic: This weekend I'm picking up a 1980 CB125 for 100 bucks. Pretty excited

[Pielz]

Owner says the kick starter won't return. Any idea what that indicates? I've read a few things but thought I'd get you all's opinion on what that might be. Here she is. Definitely needs some love but I think it has character and solid bones

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[ekpent]

 If the lever still functions it could be a return spring if not it could be more serious like a gear or pawl mechanism. Won't know till you get your hands on it.

[WhyNot2]

Return spring, more than likely,............ you'll have to split the cases to get to it. Will be a complete engine tear down.

Been there, done that. 100 bux is a good deal.

Cool looking bike.......if you consider parting with that "30 pack Coors" carrier on back let me know?

[Pielz]

I figured I'd probably have to split the case! I'm glad its such a small engine and I can get it out by myself with no extra tools or crazy hassle. Are there any good videos or guides out there that you know of for this bike? Also is there a range of years where the engines are identical?

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[Pielz]

Question for you folks. Im looking on eBay and I see plenty of whole carbs for basically nothing. Think id be better off rebuilding the original carb? Or just buying a new one for like 50 bucks

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[onepieceatatime]

Cool find! You never know what you will get from ebay. If you haven't cracked yours open yet, I would suggest to at least wait to see whats inside. You may not need to do anything with it other than a light clean, or it could be all varnish inside. I would probably buy one anyways just to have a spare, if they are OEM and that cheap.

[Pielz]

They're not oem. OEM is about 100 bucks. I was preemptively ordering a rebuild kit and gaskets and was considering spending a little more and just buying a new carb but yeah, I'll see the state of it first. Looks okay in pics but who knows whats in that bowl lol. I think it might be missing the boot to the airbox too

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[grcamna2]

Did you get any of the headlight parts Pielz ?  I believe the problem may be one of 2 things on the kickstart return:either the spring broke or the inner spring-stop on the inside of the right case broke,either way,you'll need to split the cases.Do you have any of the parts for the key lock on the ignition switch? Those switches are unobtanium here in the US;I bought one for mine from DSS over in the UK.I love those little CB125S bikes and would like to help you get this one going.I do have a few parts and the oem factory binder Service manual and experience on what will work or not on that bike.

[grcamna2]

I figured I'd probably have to split the case! I'm glad its such a small engine and I can get it out by myself with no extra tools or crazy hassle. Are there any good videos or guides out there that you know of for this bike? Also is there a range of years where the engines are identical?

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The 1976' model CB125S started with the 2-piece cylinder head.They are the same engine between 76'-80'.I have a 1981' CB125S and it has CDi and uses the exact same crankcases as the XL185,in fact I run an XR185 engine in mine with XL185 alternator.
Did you get a title,etc. with the bike ?

I would recommend you rebuild your oem Honda carb rather than buy a cheap china carb online.

[WhyNot2]

Rebuild on the original carb, course I bought one off of ebay, seems to spit too much gas into the engine, always smells of gas when running.

But it fires right up, no choke or anything, even after sitting for a week,

I do have the original carb rebuilt and ready to go back on, once I finish playing.

Another option: If it runs good, and you don't want to tear into it, with it being small and light weight, you could just jump start it and ride clyde.

I did that for a few month for mine, till I got the nerve up to tear into it to change the shaft. (have never tore into an engine b4 that.)

[Pielz]

Did you get any of the headlight parts Pielz ?  I believe the problem may be one of 2 things on the kickstart return:either the spring broke or the inner spring-stop on the inside of the right case broke,either way,you'll need to split the cases.Do you have any of the parts for the key lock on the ignition switch? Those switches are unobtanium here in the US;I bought one for mine from DSS over in the UK.I love those little CB125S bikes and would like to help you get this one going.I do have a few parts and the oem factory binder Service manual and experience on what will work or not on that bike.

I'm not sure what parts he has for it! Truck isn't available till Sunday so I'll be getting it then and I'll be sure to ask if he has any of the missing stuff. He said he doesn't have the key and that's why the wiring is all ripped apart like that. And I would greatly appreciate any help you')d be able to give me! This will be my first engine tear down and there's certainly not as much love for these bikes online as our 750s!
 
Also to answer the questions in your other comment the guy doesn't have the title. I figured I'd just do the Vermont trick lol. Also thanks for the info! I'm kinda glad this model has points. Sourcing a CDI is probably difficult. Also it's good to know the range of years that ran the same engine, so thanks for that info! That'll help in my online searches. There's a guy on YouTube who has a teardown video of a 73 or 74 but I'm not sure how much of that info is applicable to my engine.

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[Pielz]

Rebuild on the original carb, course I bought one off of ebay, seems to spit too much gas into the engine, always smells of gas when running.

But it fires right up, no choke or anything, even after sitting for a week,

I do have the original carb rebuilt and ready to go back on, once I finish playing.

Another option: If it runs good, and you don't want to tear into it, with it being small and light weight, you could just jump start it and ride clyde.

I did that for a few month for mine, till I got the nerve up to tear into it to change the shaft. (have never tore into an engine b4 that.)

Haha! I ordered the rebuild kit and I'm thinking I'll just make do with what I have, if possible. I'm happy to hear from someone who has experience with the eBay carbs for this bike.
 
Also what was the issue with your kick starter? Did the shaft shear or something? Or was it just a spring? I'll be in the same boat, I've never torn in to an engine but I've watched about a billion videos of people doing it for various models of bike on YouTube so hopefully I'll have a better idea of what I'm doing.

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[WhyNot2]

Rebuild on the original carb, course I bought one off of ebay, seems to spit too much gas into the engine, always smells of gas when running.

But it fires right up, no choke or anything, even after sitting for a week,

I do have the original carb rebuilt and ready to go back on, once I finish playing.

Another option: If it runs good, and you don't want to tear into it, with it being small and light weight, you could just jump start it and ride clyde.

I did that for a few month for mine, till I got the nerve up to tear into it to change the shaft. (have never tore into an engine b4 that.)

Haha! I ordered the rebuild kit and I'm thinking I'll just make do with what I have, if possible. I'm happy to hear from someone who has experience with the eBay carbs for this bike.
 
Also what was the issue with your kick starter? Did the shaft shear or something? Or was it just a spring? I'll be in the same boat, I've never torn in to an engine but I've watched about a billion videos of people doing it for various models of bike on YouTube so hopefully I'll have a better idea of what I'm doing.

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My shaft was completely stripped.

Tried the "drill a hole" thru the pedal and shaft, didn't work.

You might want to look at that, maybe the pedal is just loose on the shaft.

You won't know till you get it in your possession.

Keep us posted.

[grcamna2]

I figured I'd probably have to split the case! I'm glad its such a small engine and I can get it out by myself with no extra tools or crazy hassle. Are there any good videos or guides out there that you know of for this bike? Also is there a range of years where the engines are identical?

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You will need a 4-prong spanner socket to split the cases,for the primary drive gear on the crankshaft under the oil slinger plus the clutch hub.They're 1/2 drive and you can use a low power 1/2" impact gun to remove them;just remember when you tighten it up,use a torque wrench,not more than 36 ft/lbs.

[Pielz]

Awesome thank you!!! I was thinking of making my own tool out of a socket as I've seen others do. Although I may just order one. Do you know the measurements? Like which specifically to order? Or is it universal for Honda's?

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[grcamna2]

Awesome thank you!!! I was thinking of making my own tool out of a socket as I've seen others do. Although I may just order one. Do you know the measurements? Like which specifically to order? Or is it universal for Honda's?

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The tool is a good deal to buy as it comes with two sides 20 & 24mm;it'll work for all the little Honda's;I haven't used it in a bit but should be the 24mm large size.

[Pielz]

What size is the one that the 750s require? Do you know? I'll look around a little on eBay for the 20/24 mm one too. I bet it says in the manual what part number it is

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[Pielz]

What size is the one that the 750s require? Do you know? I'll look around a little on eBay for the 20/24 mm one too. I bet it says in the manual what part number it is. I'll have to look when I'm off work!

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[grcamna2]

What size is the one that the 750s require? Do you know? I'll look around a little on eBay for the 20/24 mm one too. I bet it says in the manual what part number it is

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I don't know,sorry.

[Pielz]

Rebuild on the original carb, course I bought one off of ebay, seems to spit too much gas into the engine, always smells of gas when running.

But it fires right up, no choke or anything, even after sitting for a week,

I do have the original carb rebuilt and ready to go back on, once I finish playing.

Another option: If it runs good, and you don't want to tear into it, with it being small and light weight, you could just jump start it and ride clyde.

I did that for a few month for mine, till I got the nerve up to tear into it to change the shaft. (have never tore into an engine b4 that.)

Haha! I ordered the rebuild kit and I'm thinking I'll just make do with what I have, if possible. I'm happy to hear from someone who has experience with the eBay carbs for this bike.
 
Also what was the issue with your kick starter? Did the shaft shear or something? Or was it just a spring? I'll be in the same boat, I've never torn in to an engine but I've watched about a billion videos of people doing it for various models of bike on YouTube so hopefully I'll have a better idea of what I'm doing.

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My shaft was completely stripped.

Tried the "drill a hole" thru the pedal and shaft, didn't work.

You might want to look at that, maybe the pedal is just loose on the shaft.

You won't know till you get it in your possession.

Keep us posted.

I plan to! Tomorrow morning I'll be grabbing it I'll be sure to give it a good look over. Fortunately I have Monday off so I'll be devoting my day to that

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[Pielz]

What size is the one that the 750s require? Do you know? I'll look around a little on eBay for the 20/24 mm one too. I bet it says in the manual what part number it is

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I don't know,sorry.

https://www.ebay.com/itm/110919889355

this is what I ended up ordering

Also it would appear as though the k7 750 uses a 24mm spanner so that's perfect if I ever have to use it on my 750!

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[grcamna2]

Looks good

[Pielz]

Picked up that bike this afternoon! Got it home and it's definitely missing a few things.

I noticed it's missing:

An ignition coil
Headlight bucket
Battery strap
Side covers
Rubber airbox boot
Key
Among other things here and there
 
I'm surprised that it has:

A decent set of points with little wear
Original (or at least Honda) exhaust
Original seat pan with an aftermarket cover job
A completely shiny rust free tank
All the cables intact although the front brake cable is seized

The engine is definitely seized. The kick starter is stuck down and won't come up but will move down a little. Just won't turn the engine. I think the cylinder is just stuck at the top of it's stroke. Valves look okay and I squirted a bunch of oil in the valve cover and on the guides as well as filled the cylinder with PB blaster.

Fortunately the carb isn't stuck and the throttle slide and choke plate move great. I'm excited to tear in to it tomorrow.

Also the front and rear suspension feel great. No leaks in the forks surprisingly.



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[grcamna2]

Looks good as a project bike for $100
You might wait a while then stick the bike in 5th gear,loosen the spark plug(or remove it) up quite a bit so it won't hydro-lock when attempting to free it up.Then rock the bike back and forth,forward-backward until the piston starts moving again.Th list of parts you need I don't have:Ebay has some of them.I would be sure to get the correct front brake cable according to the Honda part #,some of those cables online don't fit.I would guess the main item you need is the ignition switch,DSS is your best place:they only charge $10 shipping per order from Enland(they have a US warehouse in Hanover,PA.)plus I never get charged tax ! I would make your first oem Honda parts order from them.
You can search online first just to see(search using the part#'s)if you can purchase stuff there.

[Pielz]

Looks good as a project bike for $100

Thanks! Yeah I thought so. So I had a question. I know the clutch is geared right to the kick starter right? I've seen that in the diagrams in the manual. I'm a little fuzzy on the technical details yet as I haven't spent as much time studying these bikes but do you think if the clutch is stuck that that could have something to do with the kick starter not wanting to come up? Its definitely connected to something in there and isn't totally sheared or anything as it does make the positive clicky sounds of a kick starter moving when the pedal is moved through it's available range.
 
Basically I'm wondering, if the clutch plates are seized and so is the piston, and they free up with some work, what do you rate my chances that that is the issue with the kick?

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