Honda CB TDC 125 Project

[richjp]

God stuff as always Mike - thanks. Sorry about the photo of the gears - attached again.

It was good to have the thing apart even if in the end it maybe wasn't warranted - all good learning stuff!

Looks like a new cam chain make sense! That looks nasty! However, as this isn't a TDC engine, I guess I need to look for one for a CD 125 T? The driven sprocket and the actual chain in this engine are different from what's on a TDC I think - this driven sprocket only has one set of teeth and the chain make up is different - see photo. I think the TDC sprocket has two sets of teeth and a different chain design?

I'll also take a look at the valves etc. Not sure about a new barrel - will muse on it. Good luck with the head!
cheers
Rich

[lozza59]

nice job so far keep us updated
have you got a pic of the cam on its own?
i saw a cb on ebay that looked a bit muddled up and not just the engine! its fairly new being an 04 plate though,

https://www.ebay.co.uk/itm/honda-cb-125-t-/110718903825?pt=UK_Motorcycle_Parts&hash=item19c75c6611

[Teflon-Mike]

[humanbeing]

[Teflon-Mike]

[lozza59]

yes that 'cb 125 t' looked like a bitsa to me too.

[richjp]

Hi guys

Iozza - here's a photo of the cam shaft from my engine - need to make sure I get the right timing chain for it as it's not the same driven sprocket as a TDC and therefore the chain itself is probably different. I'm assuming that a chain for a CD-125 T would be appropriate?

In my limited experience of all of this I would imagine you would need to split the crank case to change the chain, but I'm sure Mike will confirm or deny that!

cheers
Rich

[Teflon-Mike]

OK.... anomolouse!
What your pic shows is a Hi-Vo 'gear' tooth plat chain, rather than a roller chain, either 'simplex' like a standard drive chain in miniature, ie one 'row' of tooth holes, or 'duplex', two rows of tooth holes, as the CB125's cam chain.

OK.... E-bay:- "CAM CHAIN CB125 TDC SUPERDREAM CD125 CM125 HONDA"
https://i15.ebayimg.com/07/i/001/2c/5c/3958_12.JPG
"PART NOS CC25T2X94; TO FIT MODELS , HONDA CB125T / TDC /TDE / SUPER DREAM..CM125 / 200T CUSTOM /... CD185T"

Well, this would seem 'helpful' ish...
BUT; bit of digging on Honda Europe Microfishe.....
Honda CB125TA 14401-399-003
Honda CB125TD-C 14401-399-003 Duplex
Honda CM125 14401-399-003 Duplex
Honda CD125 14401-230-003 Simplex
Honda CA125 14401-402-731 HiVo

SO, going back, when you researched engine No, turned up as a CA 125 Rebel Engine, and by the looks of it, thats the only variant that appears to use HiVo Cam Chain... BUT I am going by pictures!

You are now going to 'ouch'..... £30 from Dave Silvers Spares
E-bay offers two, but one is duplx CB chain, othr a DID at £45!

My advice, don't 'guess'... if you order one, order from Dave Silvers, and do so quoting engine number and 'description', (Ie Hi-Vo Chain) and let them tell you what you want!
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Teflon-Mike]

[richjp]

as normal Mike - fantastic info cheers. I have emailed David Silver as you suggested.

I still can't find much info on a CA Rebel being around in 1984 - perhaps it also had five gears like the CB TDC?

cheers
Richard

[richjp]

Heard back from David Silver - the engine is a 1997 CA 125 Rebel V apparently, which also had five gears like the TDC. Anyway I have ordered a cam chain.

I have managed to get all the old gasket stuff off the various joins, but have now hit a problem. The screw that holds the tach cable (which is damaged so I'd like to remove it) where it enters the lh crank case cover is completely stripped - impact driver could get no purchase. I have tried to drill it out, but no joy so far - and a broken drill bit. How long is this screw? I couldn't see what it looks like from https://www.hondaoriginalparts.com/honda_motorcycle_parts_selection_pfk.php?block_01=13KC101&block_02=E__0600&block_03=1324 - is it #17 in the picture.

Any tips for drilling out screws?

cheers
Richard

[lozza59]

i tried drilling bolts out but usually unsuccessfull, i usually go for the hammer and chisel option not a nice way but hasnt failed me yet! i smack a notch on the outside of the bolt and then bury the falt blade screwdriver into it and smack it in the 'undo' direction. here is my oil pump housing screw/bolts from the jialing motor i stipped today!

[Teflon-Mike]

[richjp]

Thanks again both. Although I have started drilling, I haven't got very far, so I might be able to fashion a new slot and go back to the screwdriver.

I'll let you know how I get on - pain because the new cam chain arrives tomorrow and I want to get back to the engine, but feel I need to finish what I've started with the screw - preys on your mind and irritates!

cheers
Richard

[richjp]

Many thanks both of you again - spot on! I fashioned a new slot with an old chisel big enough to get the impact screwdriver blade in and then three or four almighty wacks with a hammer and it came loose!

I also managed to get the knackered inspection cover off from the left hand side.

New cam chain has arrived and gaskets (have got the old stuff off all edges) - so will rebuild the bottom half. Still undecided what to do about the barrels/pistons - barrels look OK, so perhaps just new pistons. But then maybe for a few extra quid, may as well get new barrels. Will ponder.

cheers
Richard

[richjp]

I see there are two kits:

https://www.ebay.co.uk:80/itm/NEW-Cylinder-barrel-kit-Honda-CB125T-CB125TDC-CM125-/370492045960

and

https://www.wemoto.com/bikes/Honda/CB_125_TDC_TDE_Superdream/82-87/picture/Barrel_and_Piston_-_Assembly

the first is cheaper and silver and the latter is more expensive and black.

Any other differences other than price and colour?

cheers
Richard

[lozza59]

cant really help you on the differences in the cylinders/pistons kits they look the same to me, i think ebay version is chinese made and quite possibly the wemoto version is too. but i did notice this on the wemoto site!

https://www.wemoto.com/bikes/Honda/CB_125_TDC_TDE_Superdream/82-87/picture/Cam_Timing_Chain_DID_-_Rivet_Link/

so this is for the cam chain right, which means the chain could possibly be removed through the top of the engine? i do wonder because there is a odd coloured link in the cam chain i just removed.... also while your inside your engine do you plan to replace any bearings? i dont know if its a good idea or what it would cost but whilst its in bits it could be worth while.

[richjp]

Unless Mike has any strong opinion I'm thinking I might go for the cheaper one! I guess if in stage 2 I get to putting in a real TDC engine, I could reuse this and paint it black. Anyway, that's a way away in the future - lots to do on stage 1 yet! I was thinking that if I got new barrels with pistons then all would fit nicely together, whereas if I just get new pistons and use the current barrel, then maybe that might introduce an issue of new pistons not fitting as well? Or am I talking rubbish?

On the cam chain (but again no expert in such things) - I didn't notice any odd link on the new chain I just got (it's come as a continuos loop), but then I didn't really look very closely. However, even if you could open a link and take the chain out, wouldn't you still need to get into the crankcase to thread the new chain around the crankshaft? Or have I misunderstood your intention?

cheers
Richard

[Teflon-Mike]

Lozza:
https://i178.photobucket.com/albums/w269/teflons-torque/Little%20Dreams/LD07%20Eng%20Build/101_0192.jpg
A chain is only as strong as its weakest link......
YES, 'soft link' cam chains have been around a long time.
You 'cut' the old chain, and HOPE not to loose the ends... using a bit of copper wire, you attach end of new chain to end of old, then wind the engine over to thread it through, and with both ends of old chain 'out' and new looped over, join ends, job jobbed.... provided you can join soft link well..... but, still 'the weak link' and soft linked chains often don't have the 'life' of a continiouse loop, and pottential that the weak link can be a 'snag point' others having same pitch and wear rate, soft link can have more flex in it, so 'catch' you gt the idea.
50/50 whether soft link is a worth while 'precaution'. You can only fit one like that IF the old chain is still doing its job.... if it's 'gone', you have to strip to loop round crank. But if its not gone, may b rattling, but could carry on doing its job, and rattling for a very long time, before it 'goes'... fit a soft link, and not get it 'quite' right, could actually CAUSE it to 'go', and fairly soon after fit......

Rich; Barrels!
The kits are AFAIK made for Lifan by on of the Chinky Subbies. I have had two of the silver ones, and not unimpressed by quality... and I just blew some PJ1 over them to make them black!

Got mine from Riders of Yeoville, roughly £80, barrel, pistons, gudgon pins, circlips, piston rings, bas & had gasket, & think last kit came with valve stem seals too! One before was £5 cheapr but didn't include gaskets, but Top End Kit was I think £6... for which I got a few extra bits of paper and a rocker cover seal!

I wouldn't bother with new pistons unless I was going to rebore; if I wasn't going to rebore, I'd b mindful of fitting new piston rings.

Its the rings and the cylinder that 'rub' and hence wear. Pistions don't rally wear out, thy just fill a space... and you buy new ones to fill bigger hole when you have bored the cylinder, so gap isn't too big for rings to fill.
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[richjp]

Thanks Mike. Will muse on it and have another look at the current barrels. cheers
Rich

[richjp]

Decided to go for the barrel and pistons - the silver ones had gone so went for the grey/black ones. I'm thinking that for this engine I'll use the existing barrels as they look fine, but put in new pistons and rings from the kit. I can then use the new barrel for stage 2. Anyway, that's the plan. cheers Rich

[richjp]

Hi guys

I have rebuilt the crankcase with new cam chain and gasket, so onto the barrels and pistons. I'm hooked!

So much so I have also taken possession of a proper TDC engine - the crank turns smoothly, but I will strip it down and rebuild to be sure. The cylinder head also looks OK, but I think it will need a new cam shaft - I see you can get those sometimes on ebay.

Anyway, I'm going to finish stage 1 and get the current engine going. When I get to stage 2 with the proper engine I guess I'm going to have worry about the electrics. Anyway, that's some way off!

Thought I'd keep you updated!

cheers
Richard

[lozza59]

[richjp]

Hi Guys

Back from our break and back to the bike! However, had a bit of a setback today - I was reassembling the detent arm and I over tightened the retaining bolt and the head sheared off. I have managed to drill it out - although the broken end pushed in to the chamber below the thread rather than coming out. But I note it's a sealed chamber anyway so the end can't come out into the crank case. The end is 'whole' (with a hole through where I drilled), so it's not like it's broken pieces and is tight in the chamber. The actual chamber thread is OK (I tested it) so I will be able to get a new bolt in (which I have ordered). Question: how much torque should I use on it?

cheers
Rich

[Teflon-Mike]