The lack of oil seal on the crank is not obviated. Trying the felt seal might help.... It is unlikely that there is a big enough lathe there to chuck the crankcase and center it to the bearing seat, but if you can, it could be done like that.
Well, we've locally got a big enough lathe alright, at least 1-1/2 ft of swing... though its accuracy (or lack thereof) is another issue entirely...! What a time I had trying to turn down the CI tappet guides! The big chuck won't grasp anything that small, so had to secure a little three-jaw in that enormous four-jaw... that in itself a workable setup perhaps, but before being forced to painstakingly re-align the whole headstock to the ways, I originally had .005" taper in about an inch-long cut - he says the machine's been like that from new (five years or more???)!!! Ah, the pains! He was formerly employed by a certain ex-pat Australian inventor with considerably higher standards... Don't get me started...
Well, here's another: The second lathe guy an hour from here who told me to expect 100,000km's service if he'd do my crank (he has no dial-indicators, mind you), on whose machine I was trying to fine-tune my crank straightness (with my own set of indicators!), said I needed to tweak it the opposite of what I'd just told him, and in a moment of personal brain-lapse I let him mislead me, he put the thing in his hydraulic press for a little squeeze, and ended up at .010" runout.
I finally got it back within .0008" (.02mm) but would that initial error have enlarged/damaged the holes in my counterweights??? Ah, the pains!!! (this is all very cathartic!).
A third machinist (things do tend to be a little compartmentalized here in India!) was entrusted with the job of installing a threaded insert where my front drain-plug had been cross-threaded. He managed that reasonably well, but in the process clamped my engine case nice and tight in his knurled, iron-jawed vice and (obviously) marred the gasket surface... well, he charged $3 for his services and thank God for RTV, but really, this is becoming ridiculous. There is a very good reason that bikes with unopened engines are strongly preferred purchases in India.
If it seemed feasible to set up a complete personal machine shop so that I could get this ONE engine built right, I'd do it...
From the service manual.
That's a great diagram, thanks. It's a curious system in that the timing case is filled with oil both from the Feed pump (via the spindles) and the Scavenge pump (via the upper valvetrain). Interestingly then, it seems one could increase flow to the crank by restricting the flow to the spindles a bit... at least to the point where the scavenge pump could handle the extra flow in the crankcase. IIRC there was a way to do this on small-block Chevrolet's - oil-galley plugs with smaller orifices that held back a little lube from the camshaft in favor of the mains/rods. In the case of Bullets, correspondingly decreased flow to the spindles/cams wouldn't seem to matter much since ultimately everything runs fully immersed in oil anyway. Especially if using the cast-iron cams that I see have oil-supply holes at their midline.
Which brings me to this: I don't fully understand how the AVL spindles were supposed to be lubed. The spindles are hollow and you'd think the oil was supposed to flow from the timing cover recesses under pressure through spindles and out through the hole at midpoint in the eccentric sleeve the cam runs on...
BUT pressure there is impossible since the spindle ends (locknuts in this case) don't actually seal in the timing cover, which in fact has a long parallel groove in the spindle recesses that would prevent any pressure building, PLUS the flatted locknuts that would actually constitute the oil's path of least resistance; So most oil would just dump into the timing case as in the old CI solid-spindle setup - but the CI cams had decent-sized oil holes to get lube to the cam bush/spindle interface. I'm doubtful as to how much oil might find its way through the AVL's small-diameter hollow spindle to the center... especially when oil's cold/thick.
Could THIS possibly be the reason for the increased wear claimed by Indian mechanics on AVL cams/spindles (remember we're in a context of poor maintenance standards where degraded oil may be run longer)? Can't help but wonder if it wouldn't be good to have a full diameter somewhere on those AVL locknuts, such that they'd better "seal" in the timing cover and oil would only flow out of the groove ABOVE the centerline of the spindles... at least that might push a little more through the spindles, there might then be a LITTLE pressure / flow there at least.
Interesting sometimes trying to figure out what the engineers were trying to do, wish we could actually inquire of someone at AVL who worked on the redesign - in some ways such a great improvement, in others a bit baffling!
BUT... back to the main issue at hand re: the breather mod: Since the timing chest runs with a pretty high oil level in it, if the crankcase was running (more?) negative pressure, it would suck that oil into the crankcase where the AVL lacks that crank seal. The scavenging pump might not then be able to keep up with the increased amount of oil, instead of it's naturally flowing back into a similarly pressured tank as per stock design. That's the "wet sumping" referred to, right?
It's weird though... this missing crank seal seems to indicate that AVL actually
purposely eliminated the vacuum in the crankcase, why else would they have deemed the oil seal unnecessary? Either that or they were using any expected negative pressure to pull oil in and better lube the timing-side main bearing, and simply oversized the scavenging pump sufficiently that it would be able to keep up? Or else???
ACE has said the lack of the oil seal is not "obviated"... I'm not completely clear what this means - would I want to entrust the whole functionality of the modded breather system to a felt seal that may or may not hold up long-term? Or is it generally expected that it could work without it?
In short
Has anyone actually changed an AVL back to the old breather setup successfully? I'd like a more efficient system but not so inclined to be a guinea-pig for the sake of a mere horsepower or so...
I'd kind of like to just get the bike back on the road now. Not rushing anything, but would prefer to not embark on experimentation that could require subsequent major disassembly.
Ah, so after all the rambling:
1) my counterweight holes... likely damaged???
2) nuances of spindle lubing and efficacy of better sealing between them and the timing cover?
3) Has anyone actually converted an AVL to the old breather system successfully, without adding an oil seal?
Thanks All,
-Eric