Are Honda cb 125 t cylinderheads interchangeable?

[125 twin]

I have 1978 Honda CB twin, and am looking fo new heads. It is somewhat project forever, but I want to ride it some day.

I found that theres on ebay for sale year 1990 or 1991 heads. Wondering, will they fit to my bike. From picture these set of heads look exactly similar to heads of mine bike, but cannot tell for sure. I of course don't want to buy heads that doesnt fit, although ok condition heads are relatively cheap.

Does someone of you know about fitment and year?
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No generalizations, not even this

[pepperami]

Teffers is your man for this enquiry.
Ask Teflon Mike.
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I am the sum total of my own existence, what went before makes me who I am now!

[Fisty]

The next post will be a wall of autism. Only one word will be relevant to the question.
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Quietly and consistently taking the piss.
TL1000R | Hayabusa | ZXR400 | TL1000S | Bandit 400 V
Fatter and faster than Fret

[Teflon-Mike]

Check CMSL; most of the Honda, and clone, 125 twins, and a few others, are 'interchangeable' on the barel.
OTMH CB/CD/CM 125's, CD185, CD200, CB two-fify, CD250, and possibly a few I forgot. They share the same bore centers,and even the same valve sizes; the diofferences where they exist tend to be inthe shape and colour of thfinning. Eg, CB125TD has black heads with square finning, earlier CB125'T' has a silver finsish head with round finning, ie cosmetic... is this important to you?
On an early CB125Twin, to me it probably would be... its a classic, and it would be nice to keep it fairly original... if youwntmore oomph, there's plenty of bikes out there that have that off the shelf... and worth mentioning the CB125 Twin, is NOT natively A1 or UK learner-legal. Manufacturers obrochure claimssuggest 17bhp, 2bhp more than you may have onn A1 licence, the thing 'should' be ;restricted, even though it is just 125cc displacement.
But the short answer is 'yes' pretty much all the heads in the Benly family of small honda twins, whether 125, 185, 200 or 233cc are interchangeable; the 'clones' and things like the Jauiling and AJS varients open up even more possibilities, vut whether you could a) get hold of,and b) would want to use any of them is amother matter.
What's wrong with the head you got?
AFAIK, they are still in productionin and avail able from China via e-bay,used on all manner of clones as well as a fair few quads if varying displacement and and probably easier to obtain and less risk than a 2nd hand or NOS genuine item.
Unless a valve guide was cracked though, I'd be inclined to recon what I had, and slap it on top of a Chinky barrel and piston kit,
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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?'

[Fisty]

[Pete.]

Early bike had different cams to the later ones. Whilst the head might fit the block, the cams might not be appropriate.

What's wrong with your current cylinder heads?
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[125 twin]

Thanks everybody...

Biie eats oil and smokes. Current heads are probably the head of the problem , if not wholly at least partly. There are also shot threads on top of the heac, and valve cover leaks The owner before me, wasn't a good owner regarding the condition of bike...

I'm not trying to make it like it was from factory, I have modified it towrds cafe racer... good to know about the heads that they are similar regarless of year..
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No generalizations, not even this

[Pete.]

[Teflon-Mike]

Burning lots of oil, would suggest that your head is probably OK.
The oil will be getting in the cylinder to get burned frome on of or both of two routes.
1. past worn piston rings in worn cylinder bores
2. Past valve stem seals that have turned to talcum powder over time.
As hinted; do a top end rebuild. Stop fretting about the cylinder head. Get a replacement cylinder and piston kit from China and recondition the cylinder head with new valve stem seals and a good valve lapping.
Put it back together, and your oil burning issue should be gone, and the starting should be better.
Again, see handy How2 in profile. {HOW2: Top End Rebuild Honda CB125 (Benley Motor)}
I can do a top end rebuild with new parts on one of tyhese things over night; even a numpty should be able to do do one, following instructions, in a weekend, and its a LOT less work and hassle than effing about with carbs and ignition points etc trying NOT to look at oily bits.
Add on Ed- Re-The rocker cover. It's screwed down with just two 'top-hat' bolts. Each top-hat holt screws over a stud, that in turn screws into the cam-cap. Ie if the rocker cover dot line up, and or the bolts seem bent, which is very likelty, the rpocker covers dont like to come out from under the frames' spine rube, and folk are wont to use brute force and bend studs.. YBW.... but misalignment of the rocker cover and or cover screws does NOT becesserily denote cylinder head damage. Even if it were, during recon, when head off, heads enough to salvage the head by plug-and-tapping or helicoiling the cover stud threads, or just replacing the cam-caps that they are actually in.
B~U~T... a lot of rocker cover weepages are down to the rocker cover seal, that sits in a rebate in the rocker cover, and is prone to not lining up, and being misaligned on fitment, anyway, even when good and new. Worse on Chinky sourced gaskets that are often not very accurate to start with. Add gloopy chit to sick them in place by frustrated spanner-man, and they are even more prone to leak... b-u-t.. there should be bog all oil pressure up there to help them leak... if there IS its probably a good sign that the piston rings/bores are shot and the pressure of petrol going bang in the cylinder is pushing past the rings and pressuring the crank case hence the cam-galery and oil ways; and a slightly diligent top end rebuild SHOULD sort all ills.. hence why I assume one of these bikes will need one, it just eliminates soooo many possibilities and so much head scratching before you even begin.
____________________
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?'

[125 twin]

[125 twin]

[terrytibbs]