Author Topic: CB750K2 build  (Read 1066 times)

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Offline Brentm83

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CB750K2 build
« on: January 30, 2014, 01:04:42 AM »
Hi all, Ive been here a while lurking in the background and figured its about time I posted some shots of what im attempting to ressurect!
As with everyone money is very tight at the moment and im quite time poor also, so this will be a slow moving build for the most part. Im trying to do as much as I can myself, both for financial reasons and also personal satisfaction.
My uncle had this bike given to him in the early 80's, as renumeration for a tenant that didnt pay his rent. It had been crashed, then parked in his shed. He bought a few bits and pieces to fix it up, which never happened. He passed away 13 years ago, at which point my father took the bike. He had all intentions of rebuilding it, and promptly stripped it down to a rolling frame. At this point he decided it was too hard and packed it away into boxes.
After a few years I realised nothing was happening with it, so I grabbed it and here we are.
The frame is a 72 k2, with a 75 engine. It has K3-K5 front forks, with twin discs on the front. Only one caliper came with the bike though.

A few pics

Offline Brentm83

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Re: CB750K2 build
« Reply #1 on: January 30, 2014, 01:20:23 AM »
Ive been through all the boxes just to mock up a bit and see what is there, and most everything needed to run is there, once Ive been through the engine and replaced bearings its mostly cosmetic work to do..

Offline Brentm83

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Re: CB750K2 build
« Reply #2 on: January 30, 2014, 01:31:57 AM »
The bike wouldnt turn over and rather than try to break it free when i was planning to open it anyway i pulled the motor/ This thing is caked in grease, dirt and oil! I had to cut the timing chain, as i was planning to replace it anyway.
Turns out #3 piston was stuck to the bore with surface rust, didnt take much to get it free but the top ring was broken and the other two stuck in the grooves, the other 3 pistons look good, apart from the carbon build uo.

Offline Brentm83

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Re: CB750K2 build
« Reply #3 on: January 30, 2014, 01:35:32 AM »
Ive pulled piston 3 and left it sitting in atf/acetone at work, hopefully they free up.
I noticed they are stamped HA-64, TOHO, CB810, so it looks to me like a Henry Abe kit?
Ill post up better pics of pistons and bores tomorrow

Offline BPellerine

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Re: CB750K2 build
« Reply #4 on: January 30, 2014, 04:38:11 PM »
most likely 64mm 810 pistons so it has been bored,take a look at your cam see if it is stock seems to be a rash of 64mm finds lately.bill
1978 CB 750K ard and webers
another anfob

Offline Brentm83

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Re: CB750K2 build
« Reply #5 on: January 30, 2014, 09:06:30 PM »
thanks Bill, hopefully that means i can get another piston if i can't save this one! any idea what number is stamped on the stock cam?
Anyone seen indents like this before? All 4 piston are the same and there is no damage to the valves that i can see
« Last Edit: January 30, 2014, 09:14:57 PM by Brentm83 »

Offline Brentm83

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Re: CB750K2 build
« Reply #6 on: January 30, 2014, 09:13:01 PM »






Offline Brentm83

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Re: CB750K2 build
« Reply #7 on: February 02, 2014, 10:04:20 PM »
quick update, managed to get the rings off today with careful hands and a dremel, luckily for me the ring gaps are 1.5, 1.5, 2.5 so cb350 rings should fit. Cleaning and waiting for parts now