CB350 1971 Restoration Project

[Laverda Dave]

Making good progress 👍

Put your wiring loom in the dishwasher on a 50c cycle with a dishwasher tablet. It will clean it nicely and make it a lot easier to identify poor connections as well as making it cleaner to work on, they really hold the dirt.

Make sure you use a dishwasher cleaner afterwards though unless you want plates tasting of dirt😐.

[BenPowell]

Engine strip down went ahead as planned on Saturday, fortunately Ash was around at work to help out with it.

Overall the condition of the engine isn’t bad, all seemed fairly clean apart from one piston and bore which would have been the seized one.

I think it was Bryan who mentioned checking the oil filter (on the newbie post) as it’s often neglected, I was finally was able to inspect it and it didn’t look too bad, I’ll put a photo below of it.

The piston bores don’t look too bad, there is some staining on the bore which was seized and a bit of corrosion, but outside of the ‘running face’ portion of the bore, I think it would probably clean up as I can’t feel any visible pits.

Ash has a Sykes Pickavant honing tool which I could use to clean up the bores, but I don’t know what grade of stone I should be using to clean up the bores?? If anyone could point me in the right direction that would be great.

Other than that I need a new cam chain and roller, (managed to get a NOS roller on eBay) since it’s been slapping the wall and worn a grove into it.
New pistons rings one of which was broken into three parts. Full gasket and seal kit for the engine.

I think I got fairly lucky with the engine, there doesn’t seem to be any major issues. Got the long process of cleaning out and inspecting all of the parts then hopefully start the rebuild in a few weeks time.

[Bryanj]

Honing takes a bit much metal out use a flap wheel, dont forget Honda piston to bore tolerance is very tight

[BenPowell]

Cheers Bryan, good shout on the flap wheel. Suppose it will be a lot more forgiving than using a stone.

Once they’re cleaned I was going to measure the bores to see how much life is in them, ideally want to avoid re-boring if possible. Hopeful they should have a bit with 8000 miles on the clock.

[Bryanj]

I commented to Ash that all our restos are never going to get ridden like they were when new, we are propably more fragile than the bikes!!!

[BenPowell]

I need to pass my test before I can even go out on mine,  Once I have though, I plan on doing a few decent trips out. Really would like to get up to the lakes.

I’m sure I’ve seen a post on here about bore tolerances so I’ll do some research to be sure.

[BenPowell]

Hi everyone,

Spent a bit of time over the weekend cleaning various engine parts and getting rounded screws out.

I started cleaning out the piston bores, nothing aggressive yet, just some scotch bright and oil to clean up the corrosion. I’ve found some pitting near the top of one of the bores which means I’m probably going to need a rebore and oversize pistons and rings.

What’s everyones thoughts on aftermarket piston kits? Are they any good or worth avoiding and paying the extra for genuine?

Bryan, still going to give the flap wheel a go, but I’ve got a feeling it might not clean it up fully

[Bryanj]

Depends how bad and exactly where the pitting is, back when i had a pet dynasore i saw lots of bad bores run, you just have to keep a VERY good eye on oil level. Aftermarket depends on the maer/supplier

[BenPowell]

These aftermarket ones (link below) seem good value, based on searching around google some of their parts have mixed reviews.

https://www.cruzinimage.net/2017/08/17/68-73-honda-cb350k-0-5mm-oversize-pistons-set/

I've got a bit of time before I need to buy some so can do some more digging around to see what's out there.

[4wDaz]

I bought a set for a 400/4 not fitted them yet but they seem bang on for the money. Nurse Julie recommended them and uses them in their rebuilds so that was good enough for me. Mine came from the Cruzing Image eBay store, that way you do get buyer protection if they don’t turn up 

[BenPowell]

That's a good sign, will take a look at the ebay store. starting to look like really good value.

Thanks

[Bryanj]

Those are good value and i know if Trigger uses them they are good. You do need to get a reborer who knows Hondas or they will bore it too big because they think Hondas clearances are too small

[BenPowell]

I’ve done some work on the cylinders tonight and had a go a cleaning up the pitted bore, I’ve got out a lot of the pitting but there is a fair bit which still remains, although it doesn’t feel too bad.

I’ve also dug out one of the bore micrometers from work and took some readings.

I used the untouched section of the good bore as a reference, measured 64.02mm which is standard spec for the engine. The worn section of the bore was 64.04mm.

Then measured the pitted bore, the bottom measures 64.06mm and the top section 64.11mm.

The pitted bore is right at the limit stated in the manual (diameter 64.1mm and taper 0.05mm) and as there’s still some pitting remaining I’m probably going to go for a re-bore, at least that can be getting done while I work my way through the other engine parts.

[AshimotoK0]

I’ve done some work on the cylinders tonight and had a go a cleaning up the pitted bore, I’ve got out a lot of the pitting but there is a fair bit which still remains, although it doesn’t feel too bad.

I’ve also dug out one of the bore micrometers from work and took some readings.

I used the untouched section of the good bore as a reference, measured 64.02mm which is standard spec for the engine. The worn section of the bore was 64.04mm.

Then measured the pitted bore, the bottom measures 64.06mm and the top section 64.11mm.

The pitted bore is right at the limit stated in the manual (diameter 64.1mm and taper 0.05mm) and as there’s still some pitting remaining I’m probably going to go for a re-bore, at least that can be getting done while I work my way through the other engine parts.

The tolerances  in the Shop Manuals are pretty  wide Ben and quite often for the the limits given... we on here would probably deem as being fooked. Trigger is your best bet for a decent rebore but he will need the pistons at the same time I think. You will probably have to go for at least +0.5 ..possibly +0.75 but I am not sure if Cruzin do +0.75.

[BenPowell]

Yeah there’s no life left in that bore anyway.

I think by looking at it I would probably get away with 0.50, I might keep going with the cleaning up and measure it once the pitting is out to see what the size is, suppose that’ll tell me what piston size I will have to go with then, or could go with 0.75 to be sure.