Author Topic: Basket case to Cr750 rep.....hopefully!  (Read 4759 times)

Offline burchy75

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Basket case to Cr750 rep.....hopefully!
« on: October 26, 2017, 10:18:03 PM »
Long story short, bought a complete Cb750 basket case off a bloke from Coventry a number of years ago with the idea of doing an original K1 resto.  Years past and nothing happened but having seen a number of brilliant CR builds on various forums, including Marks on this forum and one over at DotheTon I decided (after a few beers) to have a blast at my own.

The timing of this decision is a little off as I was made redundant in May but you’ve got to start a project at some point so despite funds being a little lacking, my enthusiasm isn’t.

The plan was to take my K0 engine here, split the cases and pour the innards (if they were in decent nick) into my K1 cases to match the K1 frame I have here.

I don’t have the CR tank and goodies as of yet but fingered a job would be needed for these outlays.  In the meantime I was hoping to build an engine and frame that I can then bling up at a later date.

So, a few weeks ago I bought an engine stand (cheers Julie) and got to work on what might be a lengthy, expensive but hopefully enjoyable first build

This is what I’ve got to start with………wish me luck!!!

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Offline Nurse Julie

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #1 on: October 26, 2017, 10:29:25 PM »
Onwards and upwards Craig.....it's the only way. Good luck with your project.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline burchy75

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #2 on: October 26, 2017, 10:30:14 PM »
Sacrificed the one on the left

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to hopefully help me get to something like this

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Offline burchy75

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #3 on: October 26, 2017, 10:31:44 PM »
Love the colour of that rep, a long way off for mine but I like to sound of a black and silver one

Offline Trigger

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #4 on: October 26, 2017, 10:37:10 PM »
Looks like you have more than enough bits to get a good start. Once the engine and frame is done, everything else just bolts on  ;)

Offline burchy75

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #5 on: October 26, 2017, 10:47:36 PM »
Sounds easy Trigger

While I've got you actually you mentioned in a post I was reading the other day about prepping cases for paint.  As mine are split at the moment, both the K0 and K1, I wanted to possibly get them sent off at some point to have them prepped.  I was thinking initially that all they would need is a good clean and then possibly bead or soda blasted but your post went into a load of detail about acid dips and the like?

Offline burchy75

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #6 on: October 26, 2017, 11:03:52 PM »
Small update

I got myself a K3 top yoke and set about it with drill, angle grinder and grinding wheel.  The plan is to turn it into a CR top yoke replica to take either my K1 forks or the later K4 forks I have here.  It all depends on the ease of doing the dual brakes on the two different fork lowers.

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As a side project I took to modelling a mirror of the K1 caliper arm and bracket.  I want to see if I can get a mould to then try and get a metal casting done.  It reminded me of pottery class at school but took a while trying to get everything lined up.  It’s a bit stone age compared to the computer design and 3d printing technologies available but it produced a mould that I’m going to play around with.  It's gonna need a fair bit of machining so may come to nothing but it’s a bit of fun  :)

As for the engine itself I set about splitting the cases so removed the gear shift bearing holder and the all the little fiddly bits.

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Luckily none of the pan screws fouled and all came out with no drama

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Having never split a case before I made the school boy error of missing a bolt and swearing a bit trying to pry the cases apart.  Luckily I fingered out I'd been an idiot before doing any damage and the cases came apart relatively easily once the last bolt had been found and undone.

Offline MarkCR750

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #7 on: October 27, 2017, 07:25:52 AM »
Good luck with the project, if you have no luck with the top yoke I have a cast one that just needs one face machining.
Suzuki GT250A (Nostalgia)
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Ducati 900SS (Soul & Speed)
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Thruxton 1200 (suits me)
James Captain 197 (pure adrenaline, i.e. no brakes!)
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Offline Trigger

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #8 on: October 27, 2017, 07:40:50 AM »
Sounds easy Trigger

While I've got you actually you mentioned in a post I was reading the other day about prepping cases for paint.  As mine are split at the moment, both the K0 and K1, I wanted to possibly get them sent off at some point to have them prepped.  I was thinking initially that all they would need is a good clean and then possibly bead or soda blasted but your post went into a load of detail about acid dips and the like?

For me the only way to get the cases clean is a soak in a tank of chemicals and then soda blast to take off any remaining lose flakes of paint. Is there a company local to you that specialises in stripping and cleaning alloy ?

Offline AshimotoK0

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #9 on: October 27, 2017, 08:50:56 AM »
Hi Craig...see Richard ....RGP750 on  here regarding casting of alloy.

Also please see PM I sent earlier today  ;)
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline burchy75

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #10 on: October 27, 2017, 09:54:57 AM »
Good luck with the project, if you have no luck with the top yoke I have a cast one that just needs one face machining.

Cheers Mark (any pics?)

Offline burchy75

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #11 on: October 27, 2017, 09:57:19 AM »
Hi Craig...see Richard ....RGP750 on  here regarding casting of alloy.

Also please see PM I sent earlier today  ;)

Cheers Ash, top bloke

I'll drop Richard a PM as well about it.  I have to admit I've been toying with having a blast at my own DIY metal casting so would be good to pick someone's brain

Offline MarkCR750

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #12 on: October 27, 2017, 08:43:45 PM »
Good luck with the project, if you have no luck with the top yoke I have a cast one that just needs one face machining.

Cheers Mark (any pics?)

I’ll see if I can find it tomorrow and post a pic on here.
Suzuki GT250A (Nostalgia)
1977 K7 CR750 (lookalike, what of I’m not sure)
Ducati 900SS (Soul & Speed)
Ducati M900 Monster (Handling & character)
Thruxton 1200 (suits me)
James Captain 197 (pure adrenaline, i.e. no brakes!)
"Eff yir gitten awvestear yir gooin te farst"
Sir J.Stewart.

Offline philward

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #13 on: October 27, 2017, 09:55:21 PM »
Good luck with the CR Craig - I'm 75% into my CR - its the hardest project I've done (most of previous projects have been standard original rebuilds) - you mod one thing and that effects the next thing you do without you realising!
Any help - let me know - loads of other CR threads on the forum too
Current Bikes:-
Honda CB750K2 (1975)
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Honda CR750 Replica (1972)
Honda CB350K0 (1969)
Kawasaki ZZR1100D3 (1995)
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Offline burchy75

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Re: Basket case to Cr750 rep.....hopefully!
« Reply #14 on: October 27, 2017, 11:24:52 PM »
Cheers Guys

With the cases now split I managed to have a look at the pistons, rods and crankshaft itself.  They all seem to be in decent nick although the number 1 rod seemed to have a fair bit of side to side play. I have no idea if this is in tolerance but as I’m going to have to get the oil clearances checked for new bearings I’ll soon work all that out.  As I’m marrying the K0 internals to the K1 cases I’m probably looking at all new bearings anyway.  The main bearings were all green in the K0 and looked in decent condition but I have no idea if they can be used again or transferred over to a new set of cases – I’m assuming they can’t?  The transmission looked to also be in good nick as well so feeling optimistic that the engine is a good un.

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While I had the crankshaft out I made notes of all the etched numbers for working out which bearings I'm going to need.

I’ve also had a blast at the carbs today and I have to say I’m pleased with how they have turned out having been attacked with degreaser and a toothbrush.  I should really get them soda blasted or bead blasted or something but it’s good getting your hands dirty and cleaning something up yourself, especially something that was as cruddy as these carbs.

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I wouldn’t eat my dinner off them just yet but it’s a start

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