Honda-SOHC

SOHC.co.uk Forums => Project Board => Topic started by: RGP750 on November 23, 2018, 10:01:22 PM

Title: CB125K3 by RGP750
Post by: RGP750 on November 23, 2018, 10:01:22 PM
Ok taken the engine out of the 125k3  it appears to be seized/stuck,
How do I get the head off, ? I cant seem to find anything on this engine.
Just downloaded a 125 175 manual but it is the later 175 engine (although it says 125k3) Grrr!

I need to split the cam chain but can't turn the engine to get to the link .
Am i having a senior moment ??

Thanks Rich
Title: Re: Help please
Post by: AshimotoK0 on November 23, 2018, 10:13:52 PM
Not sure Rich ..that's a very rare engine ..not the same as the 175's and not a variant of the SS125/CD125/CL125 The man to ask is James Morgan as he's a bit of an expert on that model I think.  I can email you his details (he worked for CMS at one time ...Coastpath on eBay ...he may even have parts to sell.
Title: Re: Help please
Post by: AshimotoK0 on November 23, 2018, 10:25:40 PM
Looking at the parts Fiche Rich ...it is in fact  loosely based on the CD125/SS125/CL125 with camchain tunnel down outside and almost identical camchain tensioner arrangement . A long bolt through the head ties the two cam covers together and two bolts fasten the camchain sprocket to the cam. The CD125 engine has a lot of similarities with the earlier Honda Benly engine.
Title: Re: Help please
Post by: RGP750 on November 24, 2018, 06:42:47 AM
That's great thanks Ash
Is there any way you can get hard copies of the micro files?
I think access to the cam sprocket is by taking off the points back plate and advance bob weights, these are stuck 'they should just slide off the shaft shouldn't they?
Any contact with someone with one would be great.
I PM'd the lead you gave me to the member on here but no reply as yet .
Cheers Rich
Title: Re: Help please
Post by: Menno on November 24, 2018, 10:51:55 PM
I have a cb 125 k6. How much are they similar?
Title: Re: Help please
Post by: RGP750 on November 25, 2018, 07:51:33 AM
Hi Menno
Images of a k6 on Google the engine looks similar.
can you put up a couple of photos one either side of the engine .
Thanks Rich
Title: Re: Help please
Post by: AshimotoK0 on November 25, 2018, 08:28:18 AM
Emailed you scans of the CD125 engine manual yesterday, from work Rich. Engine looks very similar apart from points being on the crank on the CD. Basic layout looks the same though.
Title: Re: Help please
Post by: RGP750 on November 25, 2018, 10:56:52 AM
Thanks Ash
Just printed them off, hope to have a play later .
Thanks Rich
Title: Re: Help please
Post by: RGP750 on November 25, 2018, 07:29:32 PM
A bit of progress.
Stripped the maroon off and the paint was gold and white so that's what it will be .Think the engine may have had some abuse , Tapper cover has no thread and stuck on with what looks like Araldite ,no problem that i have a NOS.
Well need a re bore and pistons,of i can get these out Ouch! looks like a bit of fun coming .
Not taken the cam shaft out yet but lobes look good .  [attach=1][attach=2][attach=3]
Title: Re: Help please
Post by: triplE675 on November 26, 2018, 03:10:06 PM
Hi Rich,
               I have restored one and
Manuals for the K3 are rare.
James Morgan was no help to me.
I have a cb175/125 pdf file and a parts book for the K3 in pdf.

I will email them when home tonight if you want them
Regards
Andrew

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Title: Re: Help please
Post by: RGP750 on November 26, 2018, 04:29:35 PM
Oh that's great thanks Andrew.
Cam bearing area is shot , will probably machine out and fit a bronze bush[attach=1].
Chances of finding a head are pretty rare i should think .
cheers for your help .
Title: Re: CB125K3 by RGP750
Post by: triplE675 on November 26, 2018, 10:00:52 PM
Hi Rich,
              My pdf files are 10Mb+
And exceed the file size on forum
Not sure how to proceed?
Regards
Andrew
Ps attached is TBM 43J(https://uploads.tapatalk-cdn.com/20181126/a01618453fd97025fcd9f5619bf3997e.jpg)

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Title: Re: CB125K3 by RGP750
Post by: Jamesh_sussex on November 27, 2018, 08:44:20 AM
Andrew. You can use a free file transfer tool called ‘wetransfer’ to send the files. Go to www.wetransfer.com. You just need rich’s email address..




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Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 27, 2018, 08:57:41 AM
Thanks for that James i'll pm you Andrew
Title: Re: CB125K3 by RGP750
Post by: triplE675 on November 27, 2018, 09:09:09 AM
Thanks James
I should have known because somebody sent files to me using that site

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Title: Re: CB125K3 by RGP750
Post by: Oddjob on November 27, 2018, 01:21:49 PM
Andrew, love the bike BTW but why does it need to sit on a block of wood under the main stand? ground uneven or is the stand slightly bent?

Also is your location Bletchley Park? Just curious as I love little puzzles like that.
Title: Re: CB125K3 by RGP750
Post by: triplE675 on November 27, 2018, 01:37:57 PM
The mainstands were scrap
And the far East replica is 1 inch too short especially as the tyres
Are TT100's
Station X is a mile away

Regards
Andrew

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Title: Re: CB125K3 by RGP750
Post by: Oddjob on November 27, 2018, 01:52:29 PM
I was always of the opinion that Bletchley Park was situated near Milton Keynes as I used to deliver around Bletchley in the 90s. However last night there was a program on called WW2 from Space which intrigued me as I am a bit of a WW2 nut. Part of the program was about the codebreakers at Bletchley Park and they had a satellite view of the UK on screen and a big pin in the shot to show where Bletchley Park was, according to them it's in Essex, somewhere near Southend as far as I could make out. I was a little surprised but didn't think it was unusual for a house to be named after another part of the country, but I've just looked it up and it appears I was right after all. Typical yanks can't even read a map properly, hope he's not the same guy who programmed the A bombs, meant for Moscow and ends up wiping out Moss Side in Manchester. 
Title: Re: CB125K3 by RGP750
Post by: Bryanj on November 27, 2018, 02:07:39 PM
Nothing wrong with wiping out Moss Side and the national computer museum is also at Bletchley Park.
Title: Re: CB125K3 by RGP750
Post by: SteveD CB500K0 on November 27, 2018, 02:25:14 PM
Beat me to it Bryan. I went to Moss Side once (by accident) as I was supposed to be visiting Siemens/GPT


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Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 27, 2018, 02:55:07 PM
Back to the topic, my main stand has a broken leg.
Going to see if any other can fit.
Title: Re: CB125K3 by RGP750
Post by: AshimotoK0 on November 27, 2018, 03:58:33 PM
I think it's the same stand as an upright CD175 Rich so at least not a mega rare part.

50500-303-030B
Title: Re: CB125K3 by RGP750
Post by: triplE675 on November 27, 2018, 07:59:06 PM
Hi Rich,
               The mainstands are a weakspot the chassis is identical to the cb175k3-k6 including the main stand.
Can you believe the money breakers want for them ?
Regards
Andrew





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Title: Re: CB125K3 by RGP750
Post by: triplE675 on November 27, 2018, 08:11:04 PM
Answering the location of Bletchley park it's within spitting distance of the station reputedly there was an underground tunnel
Between the station and park because there was so many documents being moved to London each day.
The tunnel exited at a platform
It was later filled in by railways staff after the war.
Regards
Andrew


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Title: Re: CB125K3 by RGP750
Post by: Trigger on November 27, 2018, 09:33:03 PM
There was also a airfield which is now lord grey school and the Leys going all the way to the old A5 and Westland helicopters at the bottom. I used to play in all the old buildings in Bletchley park as a kid, the only part that was occupied, was the main house that was a GPO training school  ;)
Title: Re: CB125K3 by RGP750
Post by: Oddjob on November 27, 2018, 10:26:08 PM
One went on E-Bay the other week for 10 euros.
Title: Re: CB125K3 by RGP750
Post by: Bryanj on November 27, 2018, 10:36:41 PM
That was cheap for an estate the size of Bletchley
Title: Re: CB125K3 by RGP750
Post by: Trigger on November 27, 2018, 10:47:20 PM
That was cheap for an estate the size of Bletchley

I think that kinky Ken was on about 1 Westland helicopters sold as spares or repair  ;D ;D
Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 28, 2018, 06:44:22 AM
back on the topic was that a main  stand?
Title: Re: CB125K3 by RGP750
Post by: Oddjob on November 28, 2018, 01:50:45 PM
Yes, sorry Rich we went off topic there for a bit. It was listed as a main stand for a CB125K5 but used the same part number as the K3, bit rusty but looked unbroken to me. Italian E-Bay and only one bidder for 10 euro. Would have shipped to the UK as well  :(
Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 28, 2018, 03:14:13 PM
Rats!! missed that
As Ash says all k3/4 and 175's had it,
Took mine off last night and it had been cut not broken ,Weird!
No great hurry one will turn up .
Cheers
Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 28, 2018, 07:18:43 PM
Oh Dear looks worse than I hoped .
At the mo thinking the crank may be toast as well :([attach=1][attach=2]
Anyone got a clutch?[attach=3]
Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 29, 2018, 07:03:59 PM
Well Wish me luck with this one.
Been apart before, lots of lovely red hermatite everywhere.
Looks like it has been filled with sawdust??? no idea what it all is .
No sign of any recent oil either.
When the PO put it together he wouldn't have got first gear as one of the gears was on the shaft backwards so no chance of the dogs engaging.
Managed to shift the stuck piston with a few days soaking with WD and some heat and a large hammer and 40mm ally bar, didn't take that much effort.
Title: Re: CB125K3 by RGP750
Post by: rozabikes on November 29, 2018, 07:07:47 PM
Thats a challenge mate. Right up you street I'm sure ;)
Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 29, 2018, 07:12:04 PM
Yes the thoughts of getting this wreck looking good again is what keeps me going ::)
Title: Re: CB125K3 by RGP750
Post by: AshimotoK0 on November 29, 2018, 10:21:22 PM
Oh dear Rich ...I was toying with the idea of taking on that bike in a wild moment , as they are lovely looking little bikes ...kind of glad I didn't now. No worries though, you got the holy grail parts for it i.e exhausts and engine bits are bound to be out there somewhere.

If  I can be of any help sourcing parts in Japan  then just shout and I will ask Chris  but shipping is going to be expensive...maybe France is your best bet ...I had to do the same for my CD125A sloper.

The only engine I can find in Japan currently is for a K1 but they are even rarer than the K3 so they have to be out there for the later model.

https://page.auctions.yahoo.co.jp/jp/auction/c671332893
Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 30, 2018, 06:50:23 AM
Thanks Ash
Bet you are pleased you didn't take it.
Really didn't expect to find this inside looking at the outside.
I have another crank coming this week.
Getting the cam ground and the head re bushed.
Andrew on here with the K3 says some of the 175 gearbox parts are interchangable and i have a
175 box here so will check that.
Pistons, clutch plates ,cam chain adjuster wheels etc are available from CSML or DS
Be great to resarect this engine.
Title: Re: CB125K3 by RGP750
Post by: AshimotoK0 on November 30, 2018, 08:51:55 AM
Thanks Ash
Bet you are pleased you didn't take it.
Really didn't expect to find this inside looking at the outside.
I have another crank coming this week.
Getting the cam ground and the head re bushed.
Andrew on here with the K3 says some of the 175 gearbox parts are interchangable and i have a
175 box here so will check that.
Pistons, clutch plates ,cam chain adjuster wheels etc are available from CSML or DS
Be great to resarect this engine.

Sounds like you have a plan then. Where did you find a crank so quickly  Rich?

Look at this CB160 engine my friend took apart recently !

[attachimg=1]
Title: Re: CB125K3 by RGP750
Post by: RGP750 on November 30, 2018, 08:57:52 AM
May be worse than mine Gulpl!!
just bought a really nice looking clutch complete. oil spinner complete and gearchange shaft for £50 then
he gave me 20 euros back for postage RESULT!!
Title: Re: CB125K3 by RGP750
Post by: Menno on December 01, 2018, 09:13:51 PM
Maybe a solution?

https://www.ebay.de/itm/Honda-CB-125-K3-Motor-komplett/152795006482?hash=item23934ac612:g:yewAAOSwR2RaEo9Y:rk:41:pf:0
Title: Re: CB125K3 by RGP750
Post by: RGP750 on December 07, 2018, 09:25:18 PM
Thanks Menno ,only just seen your reply.
Mine has cleaned up very well actually.
Amazing what can happen when someone carries out a "re build"
Take a look at the ill fitting head gasket, no wonder there was no oil in it,,helped to oil the outside of the engine. the gasket doesn't cover the oil return hole from the top end.

 In it's past life looks like a piston has blown up, bit of work to do cleaning up the comb[attach=1][attach=2][attach=3]ustion chamber.
Title: Re: CB125K3 by RGP750
Post by: RGP750 on December 14, 2018, 03:56:37 PM
Sent the cam away middle of last week to David Newman Cams in Orpington Kent.
What a great company 4 lobes re-profiled and main journal skimmed .
Now just to get the head re bushed to suit the cam .
This bike had been severely bodged in it's history,loads of red Hermatite everywhere .
Take look what is appearing out of the oil hole that had the most wear.
Cam back in less than a week and £60 all in Result
Title: Re: CB125K3 by RGP750
Post by: Laverda120 on December 14, 2018, 06:20:21 PM
Looking good Rich. Newman Cams are very good. Mike Newman is always happy to chat on the phone as well.
Title: Re: CB125K3 by RGP750
Post by: Trigger on December 15, 2018, 06:36:55 AM
You have to work out how to make a bush that will not spin in the housing  ;)
Title: Re: CB125K3 by RGP750
Post by: Laverda120 on December 15, 2018, 12:25:56 PM
You could try Russell at J D Autoworx in Wallington, Surrey who may be able to make a bush with a suitable peg arrangement. Last time I visited he was developing a bushing arrangement for SOHC engines.
Title: Re: CB125K3 by RGP750
Post by: AshimotoK0 on December 15, 2018, 05:21:23 PM
You have to work out how to make a bush that will not spin in the housing  ;)

I found out recently that the CD175A and CB160 cam covers were bushed as standard Rich so Honda obviously achieved it. I suppose pressing in the bush if made slightly oversize with head heated and bush frozen would achieve a tight fit and you may have to ream slightly if the bush 'pulls' in a little. I would think it would be a hell of a sight easier than doing  a similar modification to a 400/4 head but even that was achieved by Dixon racing yonks ago.
Title: Re: CB125K3 by RGP750
Post by: RGP750 on December 15, 2018, 06:25:13 PM
Thanks Guys
The Bush will be fitted as Ash says and a taper point grub screw will be fitted from the top after
the bush is fitted.
The tapping drill will go into the bush by .75mm Obviously it wont be tightened up too much because of the distortion risk.
 but will stop movement.
Title: Re: CB125K3 by RGP750
Post by: K2-K6 on December 15, 2018, 07:09:06 PM

[attachimg=1]

Found this contemporary advertisement from that era.