Project CB350F

[magpie114]

Despite stating in my new member intro thread that I was looking for a 750 to restore, I’ve ended up getting a CB350F (American import) instead. There was a post about it on this forum
http://www.sohc.co.uk/index.php/topic,29772.0.html

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Its obviously been stood for a long time and there’s a lot of surface rust but everything is solid. The tank has a couple of shallow dents but looks good internally. The mudguards have fine pitting but are free of dents and should be ok for stripping and replating. I was surprised to find the owners manual under the seat, unfortunately without its cover (I get the impression the manuals are rare and I’ve scanned it if anyone wants a copy). The first thing I noticed when sitting on it was the relatively high bars. My VFR400 is too low but this is very upright for me and it seems the bars fitted to the European model are a little lower? Anyway that’s some way off yet. The pipes are not going back on!

The frame and other parts have gone for powder coating today and and I’ve made a start on the engine. The pistons have a lot of carbon deposits. The exhaust valve in cylinder 4 was very slightly stuck open and the top ring in cylinder 3 had seized in the piston.

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A couple of the bores have very slight rusting in places - photo actually makes it look worse than it is. There was nothing worrying in the sump.

The only problem I’ve had so far during disassembly was the oil filter bolt, ridiculously overtightened. The bolt already had slightly rounded edges and would not move. Eventually ended up rounding the bolt head. I drilled thro the head and tried using my largest stud extractor but gave up at the point where I was convinced it would snap. The only remaining option then was to drill with a 20mm bit to remove the head and part of the flange. This allowed me to withdraw the housing and unscrew the remainder of the bolt. Unfortunately I caught the housing which will now need remedial work.

Reading Nurse Julie’s and Royhall’s build threads has been great preparation for splitting the cases hopefully this week. No doubt as well as a rebore and pistons, some big end and main bearing shells will be needed. I’d welcome any advice as to which ones I can reuse.

Alan

[Nurse Julie]

High handle bars are standard on all USA model CBSOHC/4's. EU and UK model bars are lower, but we never got the CB350/4's in the UK model range.
Good luck with your project.

[Oddjob]

One of the ways when I was in the trade to remove bolts like that was to use a cold chisel, position it along the edge at a slight angle, hit it hard, you want to cut into the flange at an angle that every time you hit it it tries to drive the bolt in the unscrewing direction. The combination of the shock to the bolt and the massive amount of sideways force being applied usually did the trick. If the slot you were cutting failed you’d just cut another.

[Orcade-Ian]

Hi Alan,
Glad it went to a good home!  You seem to be well on the way already and I'm sure the oil filter housing would be re-claimable with a turned 'top hat' bush pressed in but if it isn't, then I have one here - they are different (longer) than 400/4.  Are you sure it needs a rebore?  Unless you intend commuting daily up and down the M74, you might get away with glaze busting and new rings - careful measurements will soon indicate the best path.

Here's a bit about my own 350/4 journey:

http://www.stallard-engineering.co.uk/stories/Bikes/Japanese/350four.htm

I have a few bits and pieces in the toy cupboard - shout if you need anything

Ian

[McCabe-Thiele (Ted)]

Interesting read, I look forward to reading your progress.

[magpie114]

Thanks Ian for the information, its a big help. I like your rig setup and will use it as a model. I'm sure I can recover the oil filter housing but thanks for your offer.

Thinking about it you are probably right about the rebore. I've been busy labelling and bagging parts but I made a few quick measurements as a guide. I don't have any means to measure the bores but the pistons and ring gaps are within service limits. I'll measure them accurately when I've cleaned the pistons up properly. I'm not sure how of the best way to remove the surface rust film/glaze tho'.

[Johnny4428]

Hi Alan, interesting update on your latest project. I did look at that bike as a potential project, decided to settle for another 550 instead. Nothing horrific revealed which is always good. Keep us posted!

[Orcade-Ian]

Hi Alan,
You could try the 'Engine Room' in Motherwell - they ought to be able to accurately measure the bores and if within spec they could probably glaze bust them for you too.

Ian

[AshimotoK0]

Nice project to keep you busy over the winter.

If you haven't found them already, these are available in my Dropbox links.

CB350/400F SHOP MANUAL WORKSHOP

https://www.dropbox.com/s/1n3w5433jkph228/350F%20400F%20_4%20Shop%20Manual.pdf?dl=0

CB350F Parts Manual

https://www.dropbox.com/s/7pieydvznvy7nhp/CB350_F_F1%20Full.pdf?dl=0

[magpie114]

Good tip Ian thanks. I'll give them a try, they're fairly near too.

[magpie114]

Hi Ashimoto

I've already found them thanks - they're a big help. Together with the Clymer manual I feel well prepared.

Alan

[magpie114]

I’ve been distracted by a number of house and car jobs that needed doing but I finally got around to splitting the cases today. I’d removed the sump previously and thought one of the bolts was missing. Now its on the bench I’ve found that the bolt has been overtightened and the head has snapped off. I’ve removed broken studs before but I’m going to farm this out I’m not 100% confident with this one.

Other than that there are no obvious horrors. I’ll carry out a proper inspection in the next few days but so far I know I need to replace the primary chain.

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Thankfully the markings on the crank are clear and the code on the back of the crankcase is B B B B B

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The crankcase shells look generally ok to me apart from number 2 lower and possibly 2 upper which have a score marks although I’d welcome honest opinions.

So if needed I reckon the mains are B3 Black, B2 Brown, B1 Green, B2 Brown, B3 Black and big ends all 2A Yellow.

Hopefully getting the frame and bits back from powder coating this week, will feel like its really underway then. In the meantime I’ll keep chipping away at the cylinder base gasket which is resisting removal.

[Johnny4428]

Alan these shells look as if there got a bit of life in them yet! I’m not an expert and like you I would be seeking expert info or comments.

[K2-K6]

Agree they look good, a few obscure marks as you note for that #2 that you may want to change out of preference.

Reality from those says it's been exceptionally well serviced in regard to oil condition in it's life, they are near exemplary in showing very very minor running in witness marks.

[McCabe-Thiele (Ted)]

Those crankshaft codes are so clearly visible it's like a new engine - sure sign of regular oil changes imho.