Topic: 1974 cb350f - Revival

[Prospect]

This cb350 had been sitting for about 22 years in shed but often the doors were left open so it was exposed to the elements.  I wanted a cb350f to compliment my cb350 twin and cb400f so $450 dollars later it was mine.  Basically surface rust in many places and chrome was very pitted, tank completely rusted. Typical northern climate bike that's been sitting.  More importantly it was about 95% original.  14,000 miles.  I'm hoping to get this bike running for next season.










I got this 74 cb350f about 2 years ago and went to work on it late winter of this year.  These pictures are actually out of sequence as I'm mostly finished the rest of the bike and all that's left is the engine and carbs.  I checked the compression and all I was getting was about 15 and 45 psi and after opening up the top end I know why.  It was worse than I thought.  Clearly water had gotten into the cylinders and well... See for yourself.  I'm planning to take it to a machine shop for a valve job and honing.  Also, in my haste to take-off the cylinder head I broke off the number one spark plug.







What is the crusty stuff on the furthest right piston?

[HondanutRider]

Your title seems to be incorrectly calling this a 1972 model, when it clearly looks like the 1974.  Probably a typo you can correct, as your signature lists 1974.   

BTW looks like some work but should be nice when done.  Mine had also been sitting for about 20 years I figure, but at least it seemed to have been in an enclosed area.  Chrome is pitted but things cleaned-up pretty good and everything runs.

[Prospect]

Your title seems to be incorrectly calling this a 1972 model, when it clearly looks like the 1974.  Probably a typo you can correct, as your signature lists 1974.   

BTW looks like some work but should be nice when done.  Mine had also been sitting for about 20 years I figure, but at least it seemed to have been in an enclosed area.  Chrome is pitted but things cleaned-up pretty good and everything runs.

Yes, you're right about the year.  I must have had 1972 stuck in my mind from the 750 that I recently bought. 

I'm surprised that people would let these bikes deteriorate so much through poor storage but I guess back in the late eighties they weren't sought after like they are now.  Was there rust in your tank from the storage?  Twenty years is a long time,  indoors or not.

Here is what my tank looked like.  I've since removed most of the rust through electrolysis.  Then treated it with por15. 

[HondanutRider]

Yes my tank was just as bad, if not worse.  The outside looked good but the inside was very rusted.  When I cleaned it up using acid, I found a small pin-hole near the petcock.  Got that plugged with epoxy tank seal, and then the tank flash rusted again.  So I did the POR-15 thing and its been fine.

[Prospect]

So more bad news.  I just came back from the machine shop and the tech visually inspected the cylinders and said that they would need an overbore.  I think he should of used a bore gauge and not just assume. It's big bucks considering I would need to buy a piston kit as well.

So that leaves me three options.  Getting a new cb350f engine, getting a cb400f engine or getting new cylinder barrels only and using the pistons I have.  Problems is you don't know if what you've found on ebay is any better.  Anyone know of a good bore gauge?

Any suggestions?

[HondanutRider]

Of course a machine shop would say that if there is any question.  Not sure what condition your cylinders are in, but if they are cleaned-up (e.g. any crud and rust removed) and there aren't any serious pitting or gouges in the walls, then a light hone and new rings may be all it needs.  I'm not sure about availability of those rings, but maybe even yours would still be good.  Doing a hone is pretty simple to do yourself if you can rent or cheaply buy a set of stones.  Even with some small pits, I believe a cylinder is still OK for use, but it needs to be clean and smooth.  Honing will actually put a light cross-hatch on the surface so that it isn't a mirror finish.

[Prospect]

Of course a machine shop would say that if there is any question.  Not sure what condition your cylinders are in, but if they are cleaned-up (e.g. any crud and rust removed) and there aren't any serious pitting or gouges in the walls, then a light hone and new rings may be all it needs.  I'm not sure about availability of those rings, but maybe even yours would still be good.  Doing a hone is pretty simple to do yourself if you can rent or cheaply buy a set of stones.  Even with some small pits, I believe a cylinder is still OK for use, but it needs to be clean and smooth.  Honing will actually put a light cross-hatch on the surface so that it isn't a mirror finish.

I guess they would say that.  I'm gonna take it to another machine shop for a second opinion.  The surfaces look very clean and smooth. Zero pitting.  I can still get rings through ebay and was gonna change them anyway.  Some members were using these.

http://cgi.ebay.com/ebaymotors/HONDA-CB350F-CB-350-F-PISTON-RINGS-4-SETS-STD-/250715119642?pt=Motorcycles_Parts_Accessories&hash=item3a5fc9201a

I'm gonna start looking for a cb400f or cb350f engine just in case I have to do a bore job on the current engine.

[HondanutRider]

I'm gonna start looking for a cb400f or cb350f engine just in case I have to do a bore job on the current engine.

So...
http://toronto.kijiji.ca/c-cars-vehicles-motorcycles-motorcycle-parts-accessories-CB400f-engine-W0QQAdIdZ237572138
http://toronto.kijiji.ca/c-cars-vehicles-motorcycles-motorcycle-parts-accessories-CB350f-engine-W0QQAdIdZ237571894

I think you should look at restoring what you have.  It sounds to be a very good candidate.