Author Topic: CB750F2 .... silk purse from a sows ear.  (Read 5760 times)

Offline SumpMagnet

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CB750F2 .... silk purse from a sows ear.
« on: July 30, 2018, 11:59:58 AM »
Well...the beast has landed. And what a beast :)

It's a US import, first registered in 1978, but apparantly manufactured in 1977. She came from South Dakota which has hot dry summers and brutal winters, so I reckon this has hibernated for half the year and seen light use for the rest as it's remarkably rust free. I have the US title showing it being sold on to an importer in 2014, and then hung around for a few years before actually getting here. Not sure if that is normal, or if they are stockpiling to drip feed in to keep prices higher. Whatever....she's my bike now!

The seller had put a maroon tank on it to sell it, but that was badly scarred. I asked about the tank ( it had no tap or cap... and I was offered another one if I wanted it ) and both were brought with the bike so I could choose. The other one was black...and apparantly was original to the bike. The same key fits the seat...ignition and petrol cap cover....which is a good sign. Only downer for this tank is the badges have been removed and the gap filled. I hoper they only used filler....not the grinder.... as I want to try and refit the badges. The trusty magnet test revealed no traces of filler anywhere other than the badge recess, and only one small dent in the tank. Wow. Last bike I rebuilt had more filler than tank! Frame rust is minimal and surface only....nothing deep or pitted. No scars or marks on the downtubes. Haven't put the laser on it...but it looks really straight. I genuinely think it's worth what I paid.....which is a good start. Of course...there are probably loads of horrors lurking in there, and I will find out hundreds of things I should have known before buying...but hey. Sometimes...you just have to go for it.

Here's the pretties...



Horrid seat....horrid bars....really not my taste.



But refreshingly...things like the rear inner mudguard have not been sliced up, the underseat toolbox is still there, and nothing looks too shabby.



Even the engine paint looks passable. Some minor flaking, but really solid in the main and no signs of horrid road rash. One of the points cover bolts is missing.....odds on it is eaither snapped or stripped...but I have had much worse. On runners.

The tank filler neck needs a new seal and a damn good clean....but inside...it's all like this....


Some rust scabbing along the sidestand side edge....but more clean metal than rust. Should clean up a treat, and the seams look in excellent order. I saw how this looked...and chose this one immediately over the maroon one. It even has the sweet little chain to stop you losing the cap. The other one didn't.

The forks look straight and clean...and even the chrome looks OK. A few little pits....but wow. I had a 5 year old Yamaha show worse pitting than this. The chrome on the front mudguard is intact, and looks like it will even shine up nicely. Brakes...don't work...but everything is there. The sludge in the master cylinder probably...er...needs changing...



Stand on the kickstart, and she turns over freely with enough chuff chuff noises and resistance to say it has compression. No nasty clunks, scrapes or scary sounds. Just the noise of air being pumped. Not going to do more until I get a look inside.

Paperwork shows a little over 14,000 miles. Of course....I expect that to be a lie....or short a zero... but looking at this thing, I can actually believe it. I reckon this thing will clean up a treat.

I have a vision in my mind too. Mild cafe racer overhaul, with no cutting/mangling of stock parts. Dropped bars and single seat replacing ones I have to replace anyway. I want shorty 4 intro 4 pipes stopping just short of the wheel spindle, but thast may or may not happen. I am thinking gloss black with a dull silver frame, keeping the black fork lowers and chrome mudguard. Black and silver to offset the black/alloy engine with a few chrome highlights. Black fork gaiters. Fitted chrome ring headl;ight is spotless...so that will stay but on new brackets.

I have a dream.....
« Last Edit: July 30, 2018, 09:04:31 PM by SumpMagnet »
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Nurse Julie

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Re: CB750F2 .... the project begins!
« Reply #1 on: July 30, 2018, 12:37:52 PM »
Great start for a project, it won't be cheap though. Does the front wheel go round, the guard looks very, very close. All rubber bits will be an issue as will be very dry and brittle due to coming from USA, including any rubber bits in the engine. Good luck.
Im a Nurse, trust me, this won't hurt.....much !!!

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Offline SumpMagnet

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Re: CB750F2 .... the project begins!
« Reply #2 on: July 30, 2018, 12:45:05 PM »
She rolls fine, but the front tyre is fossilised.....and the rear is actually worse. Footrest and kickstart rubbers are OK...but they are about the only rubbery bits I trust. Fork seals and dust caps are cracked and dead.

Every hose will get swapped, and if the carb rubbers are dry...they will go too. Expect to replce the o rings on the little round covers on the head.

What other ones should I look out for? Don't really want to put the thing together and find oil pouring out the gearbox output shaft or some such shenanigans.
CB750F2 - in pieces
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Offline Nurse Julie

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Re: CB750F2 .... the project begins!
« Reply #3 on: July 30, 2018, 12:50:11 PM »
You would need to replace every single rubber part in the engine, O rings, seals, cam tensioner wheels bla bla bla etc. Even in a 40+ year old UK bike they are close to being knackered, if not already so, a USA bike's rubber bits were knacked years ago.
Im a Nurse, trust me, this won't hurt.....much !!!

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Offline SumpMagnet

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Re: CB750F2 .... the project begins!
« Reply #4 on: July 30, 2018, 12:56:17 PM »
LOL....the project list just got longer :)

But if you're gonna do it...do it right. Otherwise....you do it twice...and the second time usually costs more.

I'm just glad to be past the initial turkey purchase fear. That bit where it turns up and you realise you just spent a load of money and bought a rusty pile of doo-doo. I may yet turn out to be wrong, but it genuinely looks OK to me. Wonder what she looks like on the inside......
« Last Edit: July 30, 2018, 01:04:53 PM by SumpMagnet »
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Nurse Julie

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Re: CB750F2 .... the project begins!
« Reply #5 on: July 30, 2018, 01:03:02 PM »
Agree 100% with that statement. Whatever you think you are going to spend on it, double it and add a zero and you will still be underestimating 😀😀😀
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
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Offline SumpMagnet

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Re: CB750F2 .... the project begins!
« Reply #6 on: July 30, 2018, 01:08:37 PM »
I'm expecting it to soak up a couple of grand over the rebuild, but I am in no hurry and will buy what I need when I can afford it. At the end, I reckon I will still have spent less than what buying a finished one would cost....I will know what HAS been done....and I will have had the pleasure of doing it.

CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Nurse Julie

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Re: CB750F2 .... the project begins!
« Reply #7 on: July 30, 2018, 01:12:57 PM »
Engine and frame first, everything else just bolts on after that.
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
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Offline UK Pete

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Re: CB750F2 .... the project begins!
« Reply #8 on: July 30, 2018, 01:20:22 PM »
Nice project . I also have a couple of F2 projects
Was going to cafe racer them
I can't be arsed now so they will end on eBay probably

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Offline Laverda120

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Re: CB750F2 .... the project begins!
« Reply #9 on: July 30, 2018, 02:12:25 PM »
Glad to see you have started the rebuild. Keep posting progress photos to keep us all going during the longer winter nights, unless you are planning on completing the build before the end of summer 8).

Offline SumpMagnet

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Re: CB750F2 .... the project begins!
« Reply #10 on: July 30, 2018, 07:23:31 PM »
Stripdown Day 1 ..... the good the bad and the ...ugly.

The good first.
Lets be positive. So far there has not been a single stripped thread, sheared bolt or rounded off fastener. The back end is torn down and the rear wheel is out. Tank is off and the wiring all disconnected. The front end is all loosened up, and I just need to block up the front of the engine and drop the front end out. All the pinch bolts bar 1 are loose and everything is set for the last few jobs before I can pull the motor and sort the odds and ends. The bike is not sparkling as it should...so I need to work that out, but I will be doing it without the engine, just earthing the plugs direct to the frame so I can start on the engine once I clear some space in the shed.

The bad.
There was always going to be some, lets face it. It's a 40 year old bike thats been off the road for some time. There has to be a reason...and that's all part of the process. So...what did we find that we did not like today.

1) The exhaust has been off recently. All the nuts were loose, and 2 are missing. As are 3 of the 8 collets. The outside pipes had the 2 they should have. The inner ones had none. That's 4...but I said I had 5...yes. I found one in the little tray next to the battery box under the seat along with the battery strap. Hmmm... my guess....this bike had a good exhaust. Which was sold. A crappy rusted out pipe was then thrown on to sell it with the nuts done up finger tight so the headers felt attached.
2) The speedo drive was not connected at the bottom, and the screw is missing that locates it. The speedo is also quite battered when you look closely with the trip knob bent. The bezel is OK, but the chrome surround is grazed and out of shape. Worst of all...the speedo is blue faced. The tacho is green faced. One of them is not original. Any clues which is which? Can't believe I never spotted that one! Rookie error. No way I believe the stated mileage now. Not that I did anyway, in all honesty, but it was nicce to dream for a while
3) I got an oil leak. Left hand engine case. Left it on the side stand, and it was damp underneath
4) The headlamp is not original. In fact, it looks like it was never actually fitted! The wires and plug were not conected and clearly never had been. None of the clips holding the reflector into the housing were in palce either. All there....just not clipping anything. Judging by the corrosion staining..this was done a while ago, but someone has stuck a headlamp on so it had a headlamp....but never bothered to wire it in or mount it properly. Oh well...
5) Some one has tried to take the ignition switch apart, and the back is held on with a cable tie. Hmmm..oh yes...and the plug fell apart in my hand as I unplugged it. Ho hum. That's life!

The ugly.....
1) Julie was right about the rubber. Tank mounts, rear master cylinder rubbers, fork dust covers and all the little rubber mounts for electrical bits are all rock hard, crusty, or crumbling apart. But I expected it thanks to the advice on here. Still not pretty.
2) Fork seals are perished and oiling up the front, but no surprise there.
3) The seat is horrid, and the base is rusty too. Bin job I think. Not even worth putting on EBay. Sadly, the rear plastic cowl has some damage which will need repairing.
4) The wiring was a shocker. Some very odd bits of 'bridge work'. I started off carefully labelling each connector, but I soon realised this reference work may be wasted as I want to reconnect everything the way the book says....and this sure as hell isn't that!

So, tomorrow..the strip continues, and I can see how straight the frame and front end are. Plus remove the horrid forward pegs someone has added. Still gobsmacked that all the bolts have come undone with no more than WD40 and a ratchet. No breaker bars, lump hammers or swearing. Closest I came to that was the rear wheel spindle. It had corroded on the sprocket side and needed a soak before it shifted. The chain adjuster block that side was grotty too...but the other side is perfect. It should clean up OK.

Here's a bucket load of pics....



Some bits here to keep...and the tail pipe to scrap



All the backend, the little toolbox and the worlds ugliest seat. It has a row of rivets for the buttons....bleurgh. I will remove teh plastic cowl, the catch and hinge. The last two will go on whatever seat I do use in the end.


Why do I have an exhaust collet under the seat......


Swingarm out, and it's grubby in here....but not rusty. Chain is shot...but both sprockets could actually be used....I won't but...well...Worst rust is on the centre stand lower half. It's all solid though and should clean up nicely.


Not so clean under the tank, with a bit of frame rust...but again, nothing deep or serious. Coils have been messed with. One has 'CB750' in marker pen on the side. Replacement from a breakers. Both are marked 'TEK'. The corroded terminals and general state of the wiring probably has a lot to do with the spark issues.


Those are genuine FVQ shocks. They probably stil do fade very quickly....but they don't leak. They have bugger all damping, so probably don't leak due to having no oil.....


Who did this....why did they do it....can I have them shot please.


It's shiny...it's never been properly fitted. I might actually use it. The rubber boot over the bulb hole is also perished.


So here's where we stopped. A mixed bag of stuff, but impressed with the build quality. Nervous about what I will find lurking in the engine, but also prepared for that to swallow the bulk of the budget. If I get off lightly there...that leaves more for nice pipes and professional paint. I also got a real reminder of how things have changed when I picked up the rear wheel and nearly ruptured a disc. Do they use air or lead to fill the tyres?

« Last Edit: July 30, 2018, 07:42:28 PM by SumpMagnet »
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Green1

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Re: CB750F2 .... the project begins!
« Reply #11 on: July 30, 2018, 07:46:24 PM »
People do like to butcher the wiring for some reason. I'm still cutting those horrid red bullets out of mine.
And after stripping all that weight its still bloody heavy 
   
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Offline SteveD CB500K0

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Re: CB750F2 .... the project begins!
« Reply #12 on: July 30, 2018, 08:52:56 PM »
I like your style. There’s not much like a pragmatic and honest approach.

At some stage you will probably want to change the name of this thread… if you edit the first (original) post title, all subsequent replies will use that text.

Steve


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Offline SumpMagnet

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #13 on: July 30, 2018, 09:27:22 PM »
Thanks Steve :) I just did that.

I've done a few bike rebuilds in my time, but this is new territory in terms of scope and complexity. I also have a very good idea what can happen....will happen....must not happen with a project. Wish I had internet and forums for some of them! The amount of know how out there that I can tap into makes things a lot easier.

But I learnt the hard way how many nasties can lurk. A supposedly low mileage Guzzi LeMans with a clutch plate that had sheared rivets. Was fine until one landed in between the plates. Or a Kawasaki with a frame scarred on the downtube with a big gouge full of filler. That one pulled left really badly.....or a Z650 with an ovalled out headstock and an upper bearing race fixed wioth chemical metal.

The stripdown on this bike has been a breeze really. Bolts are coming undone without drilling, swearing and screaming. Nothing so far has snapped, rounded or come off in my hand. Some bits of it look REALLY clean...like the carbs. Other bits will need refinishing. Like the frame, swingarm etc. But the elephant in the room is the engine....

My parts list is growing already, but I am hooked. And so far....every part I cannot save/use is one I would have replaced anyway....and that makes me feel good. I hate ruining a classic, but changing seats, bars etc. that are not original and not usable is no crime. My rule here, though, is that I will do nothing that cannot be undone if the bike were ever to be put back to stock.

CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Nurse Julie

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Re: CB750F2 .... silk purse from a sows ear.
« Reply #14 on: July 30, 2018, 10:23:52 PM »
Will you be able to get the finished beauty out of the shed and through the house complete, or will it go back together on the front path?
Im a Nurse, trust me, this won't hurt.....much !!!

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