China brand 125cc jugs for a CL100... yea or nay?

Nitori

New Member
Hey all! First post here, did some searching around and couldn't find much, so I figured I'd run it past everyone here.

Are the "mystery meat" chinese jugs on ebay worth the money, or am I better served hunting around for a genuine Honda 125cc jug and piston. Not looking for max power, just, are they capable of not pooping after 100 miles? All I need is basic function and fit.
example:http://www.ebay.com/itm/Cylinder-Bore-56-5mm-Piston-Gasket-Honda-CB125-CL-XL-SL125-Engine-/161880752711?hash=item25b0d84247:g:wxAAAOSweW5Vdo5s&vxp=mtr

Back story: I recently acquired a free CL100 from a friend that was rebuilt, sold to him as a promising cafe project, and then... he parked it outside. For years. :( The engine seized so hard that it's not even funny- I've tried all the old tricks, marvel mystery oil, PB blaster, rocking it, shocking it, you name it. I finally got so pissed at the stupid bastard of a thing I tried to essentially chisel the piston out, and even that didn't budge it. It's FUBAR for real. So now I have to pull the head studs so I can separate the crankcase halves, and take the jug, piston, and crank to somewhere with a hydraulic press so I can get my crank back, hopefully with the rod too. ;D Funny thing is the rest of the engine and/or spares I have are in great shape- rockers look fine, cam looks fine, I have valves that look brand new and springs to match, the cam chain is in great shape, two clutches in great shape, two transmissions in great shape, the list goes on.

I'd like to revive it, and considering my jug and piston are basically trash anyways, I figure one of those Chinese jugs and piston sets is half the price of finding a NOS Honda piston and having my jug either re-machined or finding a new one.
 
Hey I used to work in the auto parts industry, sometimes they use (or steal) better alloys. ::)

Nah but that's exactly why I'm asking, I've used Chinese generic parts with great success sometimes- to where it's basically an OEM quality part, and others I'd get it, inspect it, and be like "wow, what a pile of trash." I was just wondering if anyone here had spun the China roulette, or if they were notoriously crappy, or if they've actually been used in builds before with success.
 
I installed one of those same cylinder/piston China kits on my CB125S and have put thousands of miles on it w/ good results.I went for the CB145 big bore kit and was able to fit the cylinder & 61mm piston kit on my crankcases because my 1981' CB125S has the same part# crankcases as an XL185.
The quality of the kit is Good and they come fitted/machined to factory specs(tight enough for plenty of miles)and I'm pleased.I asked here before I bought the top end kit but didn't get any feedback so I just went for it.
I see the kit you have in mind w/ that link to ebay and you shouldn't have Any problem with it.
My big bore kit has too much compression for the stock CB125S head and I'll be cutting a 'quench band' into my cyl. head to match a 63mm piston of an XL185 cylinder kit from that Chinese supplier soon(I already have the cylinder kit)and then I'll be turning my little 125 into a torquey XL185 and making sure the compression isn't too high:I sent the domed china piston along w/ a stock Honda XL185 piston to my machinist and he'll adjust the dome of it to match my street needs.
I'd say 'go for it' ;),I have had good results w/ my purchase of one of those kits.I think when China was given permission to clone the little Honda 4 stroke singles years ago it helped them make better parts for them.
 
I may have jumped the gun though, apparently those 125's have a different wrist pin than the 100s...

That, plus my head is still the 100cc head so I'd have a messed up squish. How difficult are those issues to solve? I'm guessing that's a few hours of machining work.
 
Nitori said:
Hey I used to work in the auto parts industry, sometimes they use (or steal) better alloys. ::)

Nah but that's exactly why I'm asking, I've used Chinese generic parts with great success sometimes- to where it's basically an OEM quality part, and others I'd get it, inspect it, and be like "wow, what a pile of trash." I was just wondering if anyone here had spun the China roulette, or if they were notoriously crappy, or if they've actually been used in builds before with success.
We have a few pitbikes with chinese cb copies, from 50 to 125cc, i think the only thing that hasnt broken yet is the rotating assembly, cylinders and heads so they cant be all that bad.. :)
 
Nitori said:
I may have jumped the gun though, apparently those 125's have a different wrist pin than the 100s...

That, plus my head is still the 100cc head so I'd have a messed up squish. How difficult are those issues to solve? I'm guessing that's a few hours of machining work.

Yeah,
The 125 has a 15mm pin and I'm not sure about your 100,but it may be a 14mm;if they sell a CB/CL100 piston kit? maybe that would be an option,otherwise you could install a pre 76' crankshaft/rod from a CB125S from 73'-75' as that also has 49.5mm stroke and will fit inside your cases.
They sell used CB125S crankshaft assemblies on ebay for a decent price.

I plan to trace out the circumference of the larger cylinder bore w/ my sharp scribe and then use my Dremel tool w/ a hard metal cutting bit and cut my own tapered 'quench band' all the way around the outside edge of my cylinder head.I'll just take my time w/ a steady hand and slowly & as best I can match what it should look like.I will keep an eye on my outer scribed circle and use my CB350 head as a type of guide to keep me pumped.
 

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Argh yup, just confirmed my pin is 14mm. I measured my spare, still haven't been able to grenade that stupid stuck piston out. :eek: Also, no joy on there being a Chinese 100cc jug. Not that I can find, at least.

I have found plenty of CB125S cranks, and they're probably far less money than the machining on a 100 rod, especially since the crank is press fit around it, you'd have to do some fancy jig work or disassemble. I guess maybe I'll go with that.

Regarding the head though, am I going to be throwing most of the displacement advantage away with having 100cc sized valves?
Also, if I leave the combustion chamber as-is that would theoretically raise my compression ratio, but would that necessarily be a bad thing? (translation: can I get away with not messing with it? :p)
 
Nitori said:
Argh yup, just confirmed my pin is 14mm. I measured my spare, still haven't been able to grenade that stupid stuck piston out. :eek: Also, no joy on there being a Chinese 100cc jug. Not that I can find, at least.

I have found plenty of CB125S cranks, and they're probably far less money than the machining on a 100 rod, especially since the crank is press fit around it, you'd have to do some fancy jig work or disassemble. I guess maybe I'll go with that.

Regarding the head though, am I going to be throwing most of the displacement advantage away with having 100cc sized valves?
Also, if I leave the combustion chamber as-is that would theoretically raise my compression ratio, but would that necessarily be a bad thing? (translation: can I get away with not messing with it? :p)

The valves are the same size from those model/yrs. CB100 & CB125.
I think you could get away w/ not messing w/ machining the outer sharp edge of the cyl. head,other members here have done it and been ok w/ it...
I personally want to carry stuff once in a while on my bike and take long rides and when i ride it for hrs. the higher compression ratio kind of 'cooks' the engine oil and 'pings' w/ pre-ignition so I've had to retard my ignition timing.I Don't like to retard my timing so I want to bring the CR(compression ratio) down a bit in case I HAVE TO run regular fuel w/ Ethanol.. :( I always need to run premium now and it Still pings;I would like to have the choice between regular or premium.
I've bought some bad fuel before on a Long ride far from home and that little engine was Very unhappy w/ it and I couldn't open the throttle much w/o it running hot.
I even ran some 100 octane(purple) AV fuel and that Was nice ! but it's a few $ more too. :D
 
Well that's good to hear. I'm thinking since I have a spare head to practice on, I'll polish up the combustion chamber myself to try to ease any detonation I might encounter. I've even got a spare set of valves that are no good that I can stick in there while I do it to protect the seats. I'm guessing the auto engine "cheater's method" of a thicker head gasket doesn't work as well?

Last of all, since I have to pull the head studs to get this damn jug off... I know some auto apps are torque to yield, am I gonna have to dish out for a new set of 4 studs, or am I good reusing the ones I remove? They're nice and bright with no corrosion at all so I'm not worried there, I just wonder if it's torque to yield or simple finger tight & torque the top nuts to spec.
 
Nitori said:
Well that's good to hear. I'm thinking since I have a spare head to practice on, I'll polish up the combustion chamber myself to try to ease any detonation I might encounter. I've even got a spare set of valves that are no good that I can stick in there while I do it to protect the seats. I'm guessing the auto engine "cheater's method" of a thicker head gasket doesn't work as well?

Last of all, since I have to pull the head studs to get this damn jug off... I know some auto apps are torque to yield, am I gonna have to dish out for a new set of 4 studs, or am I good reusing the ones I remove? They're nice and bright with no corrosion at all so I'm not worried there, I just wonder if it's torque to yield or simple finger tight & torque the top nuts to spec.

I think a Vesrah or OEM Honda CB125S head gasket will work w/ enough thickness;Honda even has a laminate aluminum shim head gasket for the 2-piece head later model CB125's that won't need to be re-torqued and it's plenty thick enough,it may match up to an earlier head,I haven't tried it.
The China head gasket is kind of thin but seals good..
I would take a close look and make sure the studs aren't damaged then re-install the same studs(I'd use a metric 'stud socket' which tightens down evenly all the way around)and use just a little red loctite(clean & dry the threads in both ends first)on the ends to install into the cases and then tighten them down good and snug,I wouldn't want the studs backing out later. I think the torque for the cyl. head hold down nuts is only around 12 ft.lbs. so it shouldn't be a problem.
 
datadavid said:
We have a few pitbikes with chinese cb copies, from 50 to 125cc, i think the only thing that hasnt broken yet is the rotating assembly, cylinders and heads so they cant be all that bad.. :)

I still prefer Japanese oem for a Japanese bike anyday :)

if you prefer using Japanese parts I have a CB125S .75mm overbore oem Honda piston,rings and cylinder
from my 81' CB125S w/ 1100 miles on them after being bored out;the parts are still fresh.
I removed them when I installed the CB145 kit from ebay.
I've never tried installing them onto a 1st generation 1-piece cylinder head but I do know it's exactly the same bolt pattern spacing on the studs.
 

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grcamna5 said:
I still prefer Japanese oem for a Japanese bike anyday :)

Same... what sort of price would you want for it? I was mainly looking at those Chinese jugs for their price point and the fact that I wouldn't buy something used off ebay in "good shape" only to have it show up and need a hone.

The whole idea of my build is to fix up this poor abandoned CL with "anything that fits or can be made to fit" - sort of a junkyard warrior, but a junkyard warrior done right.

The forks on it are trashed, but I've got a Yamaha TTR125 triple tree that I'm rigging up to fit, and adding a disc brake to the front. Things like that.

Right now it's looking like it'll be a CL100 with a CL125S crank and matching 125cc jug, a CB100 exhaust, a TTR front end, and whatever other jumble of parts I find need replacing. :D
 
grcamna5 said:
I still prefer Japanese oem for a Japanese bike anyday :)

if you prefer using Japanese parts I have a CB125S .75mm overbore oem Honda piston,rings and cylinder
from my 81' CB125S w/ 1100 miles on them after being bored out;the parts are still fresh.
I removed them when I installed the CB145 kit from ebay.
I've never tried installing them onto a 1st generation 1-piece cylinder head but I do know it's exactly the same bolt pattern spacing on the studs.
Nah im good.. ;)
 
Nitori said:
Same... what sort of price would you want for it? I was mainly looking at those Chinese jugs for their price point and the fact that I wouldn't buy something used off ebay in "good shape" only to have it show up and need a hone.

The whole idea of my build is to fix up this poor abandoned CL with "anything that fits or can be made to fit" - sort of a junkyard warrior, but a junkyard warrior done right.

The forks on it are trashed, but I've got a Yamaha TTR125 triple tree that I'm rigging up to fit, and adding a disc brake to the front. Things like that.

Right now it's looking like it'll be a CL100 with a CL125S crank and matching 125cc jug, a CB100 exhaust, a TTR front end, and whatever other jumble of parts I find need replacing. :D

$50+ $8 shipping
 
Though the little ends of the rods have different diameter, are the big ends the same. Could you swap the rod and piston/pin into the Chinese jug?
 
o1marc said:
Though the little ends of the rods have different diameter, are the big ends the same. Could you swap the rod and piston/pin into the Chinese jug?

I'm not sure what you're asking here... the rod is not bolted onto the crank like normal con rods are, it's actually pressed in, the two halves of the crank fit together and it's captive in there, so swapping rods is a lot of work and semi-pointless compared to just sourcing a whole used crank.


grcamna5 said:
$50+ $8 shipping

Well heck, that's about the same price as a China jug, so I'm certainly interested. Do these heads look like they would fit on that jug?

Ir2M2GTh.jpg
 
Nitori said:
I'm not sure what you're asking here... the rod is not bolted onto the crank like normal con rods are, it's actually pressed in, the two halves of the crank fit together and it's captive in there, so swapping rods is a lot of work and semi-pointless compared to just sourcing a whole used crank.


Well heck, that's about the same price as a China jug, so I'm certainly interested. Do these heads look like they would fit on that jug?

Ir2M2GTh.jpg

Yes they do.
I would also measure the spigot/crankcase hole I.D.(just for kicks)size in the top of your crankcases where the cylinder liner fits inside.The cylinder liner outer dimension on my 81' CB125S is 62mm O.D.
The next step I would make is to buy a cylinder base gasket and head gasket(oem Honda)for the 1981' Honda CB125S and fit them over the head and crankcase opening.
This might just be an optical illusion but the head on the left(the squish area seems bigger.. ::) ) somehow looks like it comes from a CB125,but I may just be seeing something that's not there..
 
grcamna5 said:
Yes they do.
I would also measure the spigot/crankcase hole I.D.(just for kicks)size in the top of your crankcases where the cylinder liner fits inside.The cylinder liner outer dimension on my 81' CB125S is 62mm O.D.
The next step I would make is to buy a cylinder base gasket and head gasket(oem Honda)for the 1981' Honda CB125S and fit them over the head and crankcase opening.

Hmm... I can't quite get a good measurement of that hole just yet (waiting on a dynamo puller and box wrench) but it seems like that would be very, VERY tight. My 100cc liner is roughly 58mm at the bottom, and the hole, as best I can measure, is measuring on the high side of 61.xx but I can't quite tell if I've got my calipers right because I'm holding them under the jug as I lift it up and try to eyeball the edges. Perhaps I can put the spare case together and measure that, but it's not the one I'll be using.

Good idea with the gasket, though. I won't pick them up just yet until I'm more confident in my measurements.


grcamna5 said:
This might just be an optical illusion but the head on the left(the squish area seems bigger.. ::) ) somehow looks like it comes from a CB125,but I may just be seeing something that's not there..

It is an optical illusion- I measured. Probably because the dirty one has a carbon ring and the clean one has been blasted somehow. The dirty (left side) one is the one I'm actually going to use- that cleaner one I bought for the valves, it has bent fins on the other side and it looks like the timing chain went awry inside of the housing, you can sort of see it in the pictures but there's big gouges and burrs in there! :eek:
 
Nitori said:
Hmm... I can't quite get a good measurement of that hole just yet (waiting on a dynamo puller and box wrench) but it seems like that would be very, VERY tight. My 100cc liner is roughly 58mm at the bottom, and the hole, as best I can measure, is measuring on the high side of 61.xx but I can't quite tell if I've got my calipers right because I'm holding them under the jug as I lift it up and try to eyeball the edges. Perhaps I can put the spare case together and measure that, but it's not the one I'll be using.

Good idea with the gasket, though. I won't pick them up just yet until I'm more confident in my measurements.


It is an optical illusion- I measured. Probably because the dirty one has a carbon ring and the clean one has been blasted somehow. The dirty (left side) one is the one I'm actually going to use- that cleaner one I bought for the valves, it has bent fins on the other side and it looks like the timing chain went awry inside of the housing, you can sort of see it in the pictures but there's big gouges and burrs in there! :eek:

I apologize,I didn't give you an exact measurement on the liner O.D. of this jug,I don't have metric calipers yet.I have SAE calipers and it reads exactly 2.450" O.D. on the lower part of this jug.
 
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