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SOHC.co.uk Forums => Project Board => Topic started by: Fenderfreak on March 31, 2018, 05:58:50 PM

Title: Cb250k3 first restoration project
Post by: Fenderfreak on March 31, 2018, 05:58:50 PM
Bought a CB250K3 which though Mot’d and running was a bit of a dog and showed it’s age. Mileage? Anyone’s guess as Mot s showed anything from 34,000 to 8,500 and back up 🤔. Visible problems, crappy paint, hand painted frames, dented and rusted chrome. Starter motor removed!

Rode home but pretty gutless,  checked compression down from 170psi to 90psi. Squirted some oil down the bores no change in compression so probably valves, last owner did say he had just done some work on the valves.

Any way now all stripped down and intend to do a complete restoration. wish me luck 😀
Title: Re: Cb250k3 first restoration project
Post by: Bryanj on March 31, 2018, 06:08:55 PM
Back in the day was common for these to shatter rings if thrashed from cold, no matter how new or old they were
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on March 31, 2018, 06:23:43 PM
better get ready to catch some bits when I take the barrels off then 😉
Title: Re: Cb250k3 first restoration project
Post by: AshimotoK0 on April 01, 2018, 10:31:58 AM
Biggest problem is cam/followers/end bearing ..notorious for pitting/scoring/wear. Getting harder and harder to find decent ones, even though around a million of that K model sold in various guises. Mainly down to lack of oil changing of course and the Americans seem worse than us for that, so even  low mile imports often have trashed top ends. At least your K3 is the 1st to have the '312' style rockers and the 'skinny' cam.... which are slightly easier to find.
Title: Re: Cb250k3 first restoration project
Post by: philward on April 01, 2018, 04:38:48 PM
Good luck with the build. I have a soft spot for the K3 as it was my first road bike - New in Sept 71. I had shattered ring thing that Bryan commented on.
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on April 01, 2018, 05:08:17 PM
My intention is to get the cam and rockers re chromed and profiled as well as replace all bearings, rebore etc. Using this first restoration as a steep learning curve so hopefully my next one will be easier and hopefully cheaper 😉

But will probably be just as hard and expensive. 😀
Title: Re: Cb250k3 first restoration project
Post by: AshimotoK0 on April 02, 2018, 07:57:07 AM
My intention is to get the cam and rockers re chromed and profiled as well as replace all bearings, rebore etc. Using this first restoration as a steep learning curve so hopefully my next one will be easier and hopefully cheaper 😉

But will probably be just as hard and expensive. 😀

I think they Stellite weld and grind back to shape John..no plating involved. Probably cheaper to get a nice used  set from the States or  even DK if you are lucky...decent used are around ..just take some trawling on the internet. I put 25k miles on my K3  (plus the 10k it had on it when I got it) and the cam & rockers were near perfect but I changed the oil ! Don't forget to look at CL/CB350 .... same cam & followers.
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on April 02, 2018, 05:54:49 PM
Thanks Ash, I think I will be bothering you a lot in the next few months 😉
Title: Re: Cb250k3 first restoration project
Post by: AshimotoK0 on April 02, 2018, 07:29:58 PM
Thanks Ash, I think I will be bothering you a lot in the next few months 😉

No worries at all John .. glad to have another CB250/350K owner on board. If you need any advice/parts just shout.
Title: Re: Cb250k3 first restoration project
Post by: Laverda Dave on April 07, 2018, 11:20:57 AM
John, if you don't have any luck obtaining good s/h cam and followers Newman Cams can metal spray and reprofile your originals as they did for the cam and followers of my CB250RS. First class service as well.
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on April 07, 2018, 12:51:22 PM
Thanks for that, I’ll get a better idea of what actually needs doing when I start in the engine properly
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on June 30, 2018, 11:10:52 PM
Quick update, rolling chassis nearly done, then can start stripping down the engine 😉
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on August 09, 2018, 09:34:41 AM
Finally on its own two wheels
Title: Re: Cb250k3 first restoration project
Post by: K2-K6 on August 09, 2018, 10:01:33 AM
Looking very smart.

It's a nice getting over that threshold of a rolling bike and starts to feel like real progress.
Title: Re: Cb250k3 first restoration project
Post by: mickwinf on August 09, 2018, 11:56:38 AM
looking good, same colour as my k4 i had when i was 17, went to isle of man twice on it, but did have the piston problems mentioned.
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on August 09, 2018, 01:51:35 PM
It’s getting there, rebuilding the seat this afternoon😀
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on November 02, 2018, 11:09:09 PM
Bit of an update, rolling chassis now complete, see picture, just the engine to do!

Bit of a disaster area once opened up, the cam chains at some point has given up the ghost and caused a bit of damage . Found lots of debris in the bottom and in the filter. The filter was totally clogged with aluminium fillings which appears to have come from the crank support being worn away by the cam chain, Fun this restoration lark 😀[attachimg=1]
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on October 09, 2019, 11:38:20 AM
Ok nearly there, quick update and should be all done in a couple of weeks 😀

Engine back in and now starting to put the back on. My box of parts is emptying nicely
Title: Re: Cb250k3 first restoration project
Post by: AshimotoK0 on October 10, 2019, 10:37:08 AM
Looking spot on ... who did your paint?
Title: Re: Cb250k3 first restoration project
Post by: Laverda Dave on October 10, 2019, 10:59:53 AM
Coming together very nicely.
Forget the Christmas tree this year and put this in the living room with some tinsel around it 👍.
Title: Re: Cb250k3 first restoration project
Post by: AshimotoK0 on October 10, 2019, 08:17:08 PM
Picked up some shiny stuff for my '69 K0 today.[attachimg=1]
Title: Re: Cb250k3 first restoration project
Post by: AshimotoK0 on October 11, 2019, 07:46:44 AM
Prestige platers?

No I gave it to a mate to drop off at the platers I normally use but there were two companies operating out of the same premises but entirely separate from each other  and he gave it to the one he uses and not the one I use ..... cheap though £170 the pair.

I have one more set to do ..but that's for my K2 which is a long way off.
Title: Re: Cb250k3 first restoration project
Post by: paul G on October 11, 2019, 12:16:54 PM
Prestige take some beeting on price and quality but not quick ;)
Title: Re: Cb250k3 first restoration project
Post by: Oggie400F on October 11, 2019, 01:12:57 PM
Picked up some shiny stuff for my '69 K0 today. (Attachment Link)

They look rather good. Was this local?

I have some downpipes, handle bars and front mudguard I want re chroming.
Title: Re: Cb250k3 first restoration project
Post by: florence on October 11, 2019, 01:14:20 PM
they look amazing.  How do you prepare them for plating?
Title: Re: Cb250k3 first restoration project
Post by: AshimotoK0 on October 11, 2019, 02:19:42 PM
they look amazing.  How do you prepare them for plating?

No prep and still original pitted chrome on them ...just gave him them ( well via my mate) but gave them a quick clean ... turnaround was about two weeks but not sure what's happening with him ...seems a strange setup with two platers running separate companies within the same premises.  Always a lottery with chroming though. I recommended this guy to someone on here in the past and I don't think the experience was brilliant so reluctant to recommend again.

Recently Allenchrome in Pocklington did my Bomber bars ... brake lever and a one piece CB250K0 early exhaust (downpipe welded onto silencer). Quite expensive £65 for bars and £40 for brake lever and £160 for exhaust (NOS but badly pitted downpipe) but I have to say that the exhaust is absolutely superb and not an easy thing to replate to match original Japanese chrome. Really nice guys to deal with too ..not grumpy and don't treat you like an idiot.. but can be  long leadtimes and not the cheapest around.
Title: Re: Cb250k3 first restoration project
Post by: philward on October 11, 2019, 11:08:19 PM
I've got some stuff in R&S at the moment and getting them to actually do them is a nightmare, everytime I ring (when they bother to answer the phone) I get excuse after excuse, they were put in over 5 weeks ago and they still aren't done. Are Prestige as bad as that?

R&S are about 10 miles away from me, Prestige are in Mexborough? so not at all close (44 miles) but I'm seriously thinking that I'd prefer to take them there instead for the rest of my bits, of which there are a lot.
I had the same experience with RS Ken - and wasn't that pleased with finish around joins (on rear guard) when I eventually got it back - was about 4 years ago though
Title: Re: Cb250k3 first restoration project
Post by: Fenderfreak on October 19, 2019, 07:58:10 PM
Thanks Ash, it’s almost done.

The paint work is all NOS parts. Took me awhile but worked out only slightly moe expensive then a respray but I can say it’s all original Honda paint 😉

That chromeon yours looks the business. I paid £140 for just the rear guard I got from you to get plated.

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