Totally brings back memories - I had the exact model of CB125S - metallic blue - as a 16 year old bought it off my landlord for £50 in 1979 and needed something to get me to town to meet girls - you could still have L plates on a 125cc. The "rattle" (tappets?) sound of the revving takes me back. Always loved the backlighting of the speedo and rev counter at night. When I bought it I knew zero about engines - but with it all in front of you it almost invited you pull it all apart. On mine I could never work out why the timing chain was always so slack - as it turned out this was because the odds of getting oil to the cam shaft bearing were slim to none. With bare steel cam shaft on bare aluminium head and a tiny oil pump up a head stud shaft I found that it was a disaster waiting to happen and I went through two heads in no time. You need crystal clear oil, perfect gaskets and a perfect pump. OMG I nearly lost my fingers working on the split collets on the valves - a sadist designed the lack of access to the rockers. However when I found the sweet spot of the timing then this thing sang like a canary. It free-revved beautifully and being so light it whistled down country lanes. Nearly killed myself because the speed exceeded my ability to take corners. Rounding out screw heads is probably the biggest memory - I would say my swear box needed emptying every few minutes - but learnt so much about engines and still today have the confidence to tackle any engine due to lessons learned on this. Brilliant to see the attention to detail - just wish as a 16 year old I had even a tenth of the right tools and ANY new seals and gaskets! Great job!
I love your passionate trip down memory lane, brilliant reading, thank you. You are right about the aluminium head being the week point, most people recommend changing the oil every 500 miles, I will be doing this more regularly though as a litre of oil costs nothing compared to sourcing a good head these days. Tools are everything, like you I struggled as a teen-ager trying to keep my mini clubman on the road and had to improvise/ bodge everything. We are spoilt with cheap Chinese tools these days and i invest in any tool I need within reason. Thanks again for taking the time to comment. Regards Richard
@@richardjweeks 10w30 grade Oil is required. and clean out the centrifugal oil filter every 1,000 miles as it clogs up with material from the 'wet clutch' plates. As Andy S said the oil pump is tiny/weak so cleanliness is a must.
I had my old 125S modified with rotary valves. & electronic ignition. This doubled the Bhp and allowed the engine to rev to 24,000 rpm (Red lined at 22,000). The cylinder head/camshaft was the weak point on the standard 125S engine, so much so that the next iteration, the 125J had a two part head and larger bearings on the cam to help rectify it.
This is a great reference for a build I've been doing on a 72 cb100. Having all of the project documented greatly assists me in recognizing my project hangups and what I could be doing better. Thank you for publicizing your project build!
sorry for the late reply, im pleased that this build is of help to you. good luck with the cb100, is it a white one ? i think these bikes are so timelessly classic,
Just picked up a 1974 CL125s and found your rebuild. Excellent videos . I also watched your XL250 start to finish as I picked one of those up last summer. Keep up the great videos and I'll keep finding similar bikes on this side of the pond 🙂👍 Thank you!!
Thank you for the kind feedback. It's nice knowing that they are helpful to someone. My friend Andy has a channel obsessed with xl's he is my go-to reference th-cam.com/channels/CQ7qGmkLetBoFHcMxEupiA.html
It is great to have video documentation. I haven't been back to my motors yet. Just organized the shop again. Need to refresh my mind on where I left off. Cleaning and rebuilding the 1975 Honda XL250 Carb. Have a good day. I have all the top end parts ready for the 74 Dt125 also.
It's been nice getting into the engine side of things again. Just had to stop as I need a special honda box tool. Just ordered. Good luck getting back into it, it's quite cathartic.
For the Yamaha I need a case assembly tool. I left off there. I think I can split the case with a puller I have. Only reason to take apart is because the crank area is dirty. It's happening.
6:21 All cross head screws on the Honda 125 are JIS as denoted by the dot between the arms of the X. The best way to undo them if you don't have JIS is to use an Impact driver and Philips bits, normal screwdrivers tend to round out on the countersunk screws. 11:21 Screws originally, same as top right. Back in the day you could get a complete set of "Allen bolts" for the engine.
I like to start with the engine and work outward from there. Missing parts can be expensive so work out what you need at the beginning and set up eBay searches now and grab a bargain when they come up. Take your time and enjoy the process. Good luck
@@richardjweeks thank you so much for the advice just got started on the carb I inherited this bike from my dad he had a bad fall and just stopped one day and stored the bike in his house so hopefully I only have to get a few things on eBay always fun to try a few snipes tho
Totally brings back memories - I had the exact model of CB125S - metallic blue - as a 16 year old bought it off my landlord for £50 in 1979 and needed something to get me to town to meet girls - you could still have L plates on a 125cc. The "rattle" (tappets?) sound of the revving takes me back. Always loved the backlighting of the speedo and rev counter at night.
When I bought it I knew zero about engines - but with it all in front of you it almost invited you pull it all apart. On mine I could never work out why the timing chain was always so slack - as it turned out this was because the odds of getting oil to the cam shaft bearing were slim to none. With bare steel cam shaft on bare aluminium head and a tiny oil pump up a head stud shaft I found that it was a disaster waiting to happen and I went through two heads in no time. You need crystal clear oil, perfect gaskets and a perfect pump. OMG I nearly lost my fingers working on the split collets on the valves - a sadist designed the lack of access to the rockers.
However when I found the sweet spot of the timing then this thing sang like a canary. It free-revved beautifully and being so light it whistled down country lanes. Nearly killed myself because the speed exceeded my ability to take corners.
Rounding out screw heads is probably the biggest memory - I would say my swear box needed emptying every few minutes - but learnt so much about engines and still today have the confidence to tackle any engine due to lessons learned on this.
Brilliant to see the attention to detail - just wish as a 16 year old I had even a tenth of the right tools and ANY new seals and gaskets!
Great job!
I love your passionate trip down memory lane, brilliant reading, thank you. You are right about the aluminium head being the week point, most people recommend changing the oil every 500 miles, I will be doing this more regularly though as a litre of oil costs nothing compared to sourcing a good head these days. Tools are everything, like you I struggled as a teen-ager trying to keep my mini clubman on the road and had to improvise/ bodge everything. We are spoilt with cheap Chinese tools these days and i invest in any tool I need within reason. Thanks again for taking the time to comment. Regards Richard
@@richardjweeks 10w30 grade Oil is required. and clean out the centrifugal oil filter every 1,000 miles as it clogs up with material from the 'wet clutch' plates.
As Andy S said the oil pump is tiny/weak so cleanliness is a must.
I had my old 125S modified with rotary valves. & electronic ignition.
This doubled the Bhp and allowed the engine to rev to 24,000 rpm (Red lined at 22,000).
The cylinder head/camshaft was the weak point on the standard 125S engine, so much so that the next iteration, the 125J had a two part head and larger bearings on the cam to help rectify it.
I recently got a CB125s so this video is gonna come in clutch
This is a great reference for a build I've been doing on a 72 cb100. Having all of the project documented greatly assists me in recognizing my project hangups and what I could be doing better. Thank you for publicizing your project build!
sorry for the late reply, im pleased that this build is of help to you. good luck with the cb100, is it a white one ? i think these bikes are so timelessly classic,
Just picked up a 1974 CL125s and found your rebuild. Excellent videos . I also watched your XL250 start to finish as I picked one of those up last summer. Keep up the great videos and I'll keep finding similar bikes on this side of the pond 🙂👍
Thank you!!
Thank you for the kind feedback. It's nice knowing that they are helpful to someone. My friend Andy has a channel obsessed with xl's he is my go-to reference th-cam.com/channels/CQ7qGmkLetBoFHcMxEupiA.html
@@richardjweeks I watch Andy too 🙂
It is great to have video documentation. I haven't been back to my motors yet. Just organized the shop again. Need to refresh my mind on where I left off. Cleaning and rebuilding the 1975 Honda XL250 Carb. Have a good day. I have all the top end parts ready for the 74 Dt125 also.
It's been nice getting into the engine side of things again. Just had to stop as I need a special honda box tool. Just ordered. Good luck getting back into it, it's quite cathartic.
For the Yamaha I need a case assembly tool. I left off there. I think I can split the case with a puller I have. Only reason to take apart is because the crank area is dirty. It's happening.
@@ZPDSurvival I look forward to seeing it. Make sure you film it as I want to do a Yamaha 2 stroke soon
6:21 All cross head screws on the Honda 125 are JIS as denoted by the dot between the arms of the X.
The best way to undo them if you don't have JIS is to use an Impact driver and Philips bits, normal screwdrivers tend to round out on the countersunk screws.
11:21 Screws originally, same as top right.
Back in the day you could get a complete set of "Allen bolts" for the engine.
Thanks for the video❤
Brilliant video thanks for sharing with us all. 👍🇬🇧
Working on a project just like this is Mr. Richard weeks is there any tip for starting a project like this
I like to start with the engine and work outward from there. Missing parts can be expensive so work out what you need at the beginning and set up eBay searches now and grab a bargain when they come up. Take your time and enjoy the process. Good luck
@@richardjweeks thank you so much for the advice just got started on the carb I inherited this bike from my dad he had a bad fall and just stopped one day and stored the bike in his house so hopefully I only have to get a few things on eBay always fun to try a few snipes tho
Indonesia good job
Super
hello bro, where to buy a tank that is no longer in use?
eBay
Link
I have the opportunity to buy a parts bike like this, with no title. is that a good idea to restore?
It's a tough call. Depends on what is left of the original. Also I don't know how you obtain a title for a vehicle in the U.S.
@@richardjweeks Thanks
Is it normal to find the stator coil with oil?
Yes, the stator coil has oil in that case half
hello can i ask if the valve of gl125 and cb 125 is desame??
I don't know, best check part numbers online
@@richardjweeks online where, i have a 1979 cb125s and i need parts too... can u help me? thank you very much
@@gloriapop8716 try cmsnl or David silver spares or wemoto.
@@richardjweeks thank you so much...