CB466f

[Erwin83]

Time for an update, it's been too long.

The yellow CB350f 'tracker' was sold last year to a very enthusiastic new owner. The proceeds have been put forward to build a Moto Guzzi caferacer last winter, which I am riding this season, even taking it on longer multi-day trips. So this is how my garage looks like now (and there is a Transalp 650 too):

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Finishing the Guzzi gave me time to grow new spirits for working on the black CB, which has a oil leak from a hairline-crack in the lower engine casing. I discovered this after rebuilding the top-end (big bore, etc). Quite disappointing.

I tried 2 different kinds of Alu-epoxy to solve (or even just control) the oil leak, but to no success.
So last weeks, I have taken the jump to finally split the cases and look for a welder.

That's where I am now: the welder should be finished in the coming days, and a pile of parts is supposed to arrive as well, all of the "now we're here" category, such as the reworked tensioner (DS), oil seals, etc.
First time opening the cases, and I am happy to report that the internals are looking great, so definitely worth the trouble.

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[philward]

2 great looking bikes!

[Erwin83]

2 great looking bikes!

Thanks!

Progress:

Picked up the welded case last evening and checked for leaks with pressured air. All seems well now.
Due to the location of the hairline crack, we decided to weld-up the engine mount completely. There was no way a welding cup was going to get into the crevice where the nut lives, and the crack was all the way at the bottom of it. Even chopping off the engine mount, weld the crack, weld the engine mount back on, would render the engine mount useless, as the nut would not be able to fit back in.
So I'll be mounting the engine from 5 instead of 6 engine mounts from now on. Priority is with beating the oil leak.

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In the meantime, I've replaced all oil seals: both on the crank, the big one behind the sprocket, and the oil-cup next to the gearbox, and replaced the 3 O-rings of the oil galeries.
Now waiting for Fedex to bring the parts from David Silvers, and I can start closing the cases again.

[McCabe-Thiele (Ted)]

I would worry (probably unnecessarily)  about the new stress distribution with one lower side mount missing.

I guess spare casings are scarce / pricey  in the Netherlands.

[Erwin83]

Well, that is indeed a risk I am accepting. There are a lot of engine mounting positions on a small area, 4 on the bottom casing half, and 3 on the top casing half.

Apart from undamaged casings being very rare (a lot of 400's have this issue), the casings are also a match with eachother, and with the crankshaft. So changing out the casing means:
- Full engine teardown (vs. having the top-end still in place now).
- Finding the right size and changing out the crankshaft bearings.

[Laverdaroo]

Loving the Guzzi!

[Erwin83]

Loving the Guzzi!

Thanks! Me too. It's such a usable bike, I even took it to Germany for a weekend chasing my mates' Multistrada's through the twinties.
It has the vintage caferacer feeling, with modern performance and reliability.

It's for sale nonetheless.. I want to build another Guzzi next winter.

[Erwin83]

Took some time, but finally got my package from David Silver, with most importantly the re-engineered camchain tensoiner:

[McCabe-Thiele (Ted)]

I love to see Moto Guzzis I hankered for a V50 - a girl I knew bought a brand new one  sometime around 1979/80 for commuting to work- they looked great value and that bit different to other bikes at the time.
I sat on one at the local dealers but it was rather small for me at 6ft 1in with a 33 inch inside leg- that was my excuse at the time in reality it was just out of my price range.

[Erwin83]

Unfortunately, the first start after closing the cases and putting everything back together did not go exactly as planned. In order of events:
- After putting fresh oil in, I have primed the oil system (sparkplugs out) by turning the crank from the right side of the engine.
- Oil light went out, so I should have pressure
- Spark plugs in
- Gave it a shot with the startermotor: everything sounds fine
- Added some more oil to bring the level up to max
- Opened the fuel tap, start: immediately sprung to life, no weird noises. Adjusted the choke so I had a nice stable 2000 rpm to let her warm up gently
- Again, no weird noises, even the valve train sounded a lot less noisy (with the new adjuster)
- After what must have been around 30-40 seconds, there was a zzzzZZPP sound and the engine stopped.

I feared the worst, so put the bike back on the lift, she cooled down a bit and I tried cranking it over from the crank nut. Seems pretty normal. Gave it a go on the starter motor, also sounded pretty normal (even wanted to fire, but I didn't give it any choke or throttle)

I don't know what is a wise next step now, in order to understand what happened. I "only" opened and shut the cases, and replaced all oil seals. So logically I would think maybe a crank bearing gave up (maybe it didn't like the heat from the welding, although the entire case was pre-heated and clamped down on a fixing table to avoid warping).
But a zzzZZZPPP sounds more like a piston to me (?). I would think knocking or clunking is how a bearing sounds....

All advice is welcome.

[McCabe-Thiele (Ted)]

I can't hear the noise you describe in my head - if you fear running it up again my starting point would be to turn it over without the plugs in to see if there are any strange noises - drain & check the oil & filter for debris.

Check for the proper location of the camchain tensioners blades - had you done the cam chain tensioning with the engine running or had you not got that far?

[philward]

But a zzzZZZPPP sounds more like a piston to me (?). I would think knocking or clunking is how a bearing sounds....

Logically, I would agree with you, it sounds like a 'nip up' rather than a bearing failure. As per Ted's comment, drop the oil and look for debri plus maybe a compression test?
Good luck and hope its something simple and nothing serious

[Erwin83]

Seems the battery was all dry. I'm not cheering (not at all), but I'm going to try with a better battery. Not sure how the sudden stall could be caused by a bad battery, but it's an easy check.

[McCabe-Thiele (Ted)]

There is a tendency to fear the worst especially after a substantial amount of dismantling has been done. Fear for the worst hope for the best dilemma syndrome.

[Erwin83]

There is a tendency to fear the worst especially after a substantial amount of dismantling has been done. Fear for the worst hope for the best dilemma syndrome.

Yes, I always "shit 7 colors" (a dutch saying meaning you feel scared) when I run the bike after each rebuild.