Author Topic: First AVL ownership/build... tech questions...  (Read 6747 times)

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ace.cafe

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Reply #75 on: April 10, 2019, 05:06:40 pm
If the CI and AVL tappets have the same foot diameter, either type will work fine.


ringoism

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Reply #76 on: April 11, 2019, 11:58:22 am
If the CI and AVL tappets have the same foot diameter, either type will work fine.

Yes, they do, and I'll be doing the mod, thanks for your inputs. 

Now here's something: I've had 2-3 mechanics tell me recently (and curiously), that the AVL valvetrain tends to wear prematurely - incl. cams / cam gears, and spindles - that you put all new ones in and within a year or two they're getting loose / noisy again; They recommended changing everything over to the CI pieces just for the sake of durability.  Odd... I just can't imagine why this would be.  Is there a difference in the oiling system they don't understand, or could the materials for some odd reason actually be worse in the newer design, or again could the sharper ramp-up (shorter duration) of the AVL cams be putting more load on everything?   

Debating whether to take their advice.  Basanti said the CI cams were way better for speed.  I'm mainly after low/mid and fuel economy, but do want sufficient durability to be able to build it and more or less forget it for several years... that's where the above question comes in.

Anyone venture an explanation for allegedly longer valvetrain life in CI's?

On FE, one mechanic assured me there was no difference after changing to CI cams... but I really wonder, being that the duration / overlap would be more, and that stock CI's got about 20-25kmpl up here, and the AVL's/UCE's manage more like 30. 

-Eric


Adrian II

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Reply #77 on: April 11, 2019, 01:42:05 pm
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stock CI's got about 20-25kmpl up here, and the AVL's/UCE's manage more like 30

Nothing to do with the AVL's CV carb, then?

Whatever faults have arisen in the UK concerning the Electra-X nobody seems to have mentioned premature valve train wear. For the C.I models Samrat used to offer super-thick stem tappets in bronze guides (my AVL hybrid has a set, but sadly Hitchcocks' have long been out of stock). Maybe see if you can find a set.

A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


ace.cafe

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Reply #78 on: April 11, 2019, 04:55:38 pm
Yes, they do, and I'll be doing the mod, thanks for your inputs. 

Now here's something: I've had 2-3 mechanics tell me recently (and curiously), that the AVL valvetrain tends to wear prematurely - incl. cams / cam gears, and spindles - that you put all new ones in and within a year or two they're getting loose / noisy again; They recommended changing everything over to the CI pieces just for the sake of durability.  Odd... I just can't imagine why this would be.  Is there a difference in the oiling system they don't understand, or could the materials for some odd reason actually be worse in the newer design, or again could the sharper ramp-up (shorter duration) of the AVL cams be putting more load on everything?   

Debating whether to take their advice.  Basanti said the CI cams were way better for speed.  I'm mainly after low/mid and fuel economy, but do want sufficient durability to be able to build it and more or less forget it for several years... that's where the above question comes in.

Anyone venture an explanation for allegedly longer valvetrain life in CI's?

On FE, one mechanic assured me there was no difference after changing to CI cams... but I really wonder, being that the duration / overlap would be more, and that stock CI's got about 20-25kmpl up here, and the AVL's/UCE's manage more like 30. 

-Eric
There is no reason for any difference in valve train life, except the AVL has a small rocker ratio, and the CI doesn't.

The main thing between CI and AVL tappets is the valve lifter system on the AVL tappets vs the regular decompressor of the CI. It may affect the valve lifter fit.

I don't really know how to put this diplomatically, but it would be best to not listen to these "mechanics" that you seem to be consulting.
There seems to be a lot of BS floating around mechanic shops in India.


Adrian II

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Reply #79 on: April 12, 2019, 06:23:15 am
You can actually have the AVL-style valve lifter on a C.I. Bullet if you really want one.

http://accessories.hitchcocksmotorcycles.com/accessory-shop/Valve-Lifter?&model=

I don't know if they have sold many.

A.

Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


ringoism

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Reply #80 on: April 12, 2019, 01:16:33 pm
The thing about Indian mechanics is that they have no clue about theory most of the time, they operate on very strange assumptions sometimes, and surprisingly often (not always), it "works" despite the spurious bases.  Kinda like some elaborate systems of pre-Galilean astronomy... Wrong assumptions but kinda worked as a system.  What I've found is that what these guys lack in basic understanding / book knowledge they sometimes make up for by doing/ seeing every single thing just thousands and thousands of times over, and learning bit by bit what works and what doesn't.  I mean, as one example, they've been clear as anyone here about the weakness in the tappets, and worked out the same solution as people here did, too.  Independently.  My friend was telling me a few days ago how he saw a pristine paint-job being applied at an outdoor parking lot somewhere in the heart of Delhi - this was on an Audi A8 (!), and there was a lot of other high-end machinery all around, too... they certainly don't play by "the" rules, and many of us in the West find this highly irritating... But the average street-mechanic here probably builds more Bullet engines in a year than most U.K.-based specialists would in ten years.  For those who take pride in their work, there's been a lot of knowledge gleaned / applied.  Somehow they keep more Bullets (and other motor vehicles) going than practically any nation on earth. 


Well, I opened the engine today.  You'd have to go back to post#60 for reference re: why. 

Anyway, turned out to be the timing-side main bearing, the small one.

Possibly was a low-quality bearing, the race was toasted and rollers fine.  But almost certainly a contributing factor was the cam spindle.  No time to post a pic right now, but basically the flat on the flange which is supposed to keep it locked against rotating in the case just doesn't match the case very well, there's a big gap - typical crap machining I suppose.  Meaning that the spindle can probably rotate at least 15 degrees in there if the press-fit were a tad loose, which one of mine was.  Wouldn't be a problem with solid spindles (Adrian's choice here was a good one), but with the eccentrics, the trouble is that when you tighten the locknut backlash may be fine, but if in tightening it the whole spindle rotated clockwise in the case, and later at high revs it rotates back anti-clockwise, then all the lash can be gone.  The exhaust cam in this case was so tight I could hardly pry it out.  Which is NOT how I had set it last time.  There's a way to do the adjusting that would mitigate this risk (tighten the eccentric up against the rotation direction, so that if it rotates back, it can only loosen), but somehow I didn't do it that way.  So here we are.  There must have been a lot of radial load on that end of the crank.

The rod big-end seems absolutely fine, so am debating what to do now.  I kinda figure each time you take a crank apart and reassemble, the press-fits get a tad looser, which of course would create its own problems. 

So the hack who did the crank down in Delhi wasn't to blame after all.  He might've done tens of thousands of these (father did it too, he said at the peak they were doing ten per day - that's 3,000 per year, people), and yeah, he got mine to .0015" runout by eyeballing it with a piece of wire (insane).  And he says I'll get at least 30,000km's out of this.  I think he used NRB needles.  Hmmm... 

As mentioned earlier, just no budget for Hitchcock's rod kit, so is it worth tearing it down just to put a fresh pin / rod / Japan bearing in it (or experiment with my own version of Hitchcock's approach), or should I just re-check trueness and throw it back together with good quality mains (and better tappets, and do something about those spindles)?     

Hmmm...

On another note, is there some procedure for setting up the meshing / distance between the crankshaft worm gear and the mating teeth on the oil-pump shaft?  I put a new shaft in 2,000km's ago and it's looking pretty bad already.  Maybe I didn't put a new worm in, can't remember, but it too looks damaged.  I need to check the parts book and see if there's supposed to be a lock-washer or shim or something between the cam pinion gear and the oil-pump worm gear, mine didn't have any.  It seems to me the worm may be running too far inboard, such that only the outermost part of the worm is contacting the shaft's gears.  Any failures here would seem necessarily catastrophic.   

I guess I could just test-assemble with varying thicknesses of washers in between the two, till there's just a little clearance between the worm and the oil seal?  Left-side crankshaft thrust washer would also have an effect on this I suppose (I have the standard size on both sides)? 

-Eric
« Last Edit: April 12, 2019, 01:38:41 pm by ringoism »


Adrian II

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Reply #81 on: April 13, 2019, 07:45:26 am
Quote
or should I just re-check trueness and throw it back together with good quality mains (and better tappets, and do something about those spindles)? 
   

Yes. Add a good sump magnet as protection for the scavenge oil pump chamber and the rocker feed. Note that if you're fitting plain cam spindles the timing cover's spindle housings will need boring/reaming out to 5/8" to fit. Plain spindles are available in over-sizes to fit worn holes in the crankcase.

Quote
On another note, is there some procedure for setting up the meshing / distance between the crankshaft worm gear and the mating teeth on the oil-pump shaft?  I put a new shaft in 2,000km's ago and it's looking pretty bad already.

I have been caught out like this on my AVL hybrid motor. Some of the worm drives are larger diameter than others. I was also finding bad premature wear on the oil pump spindle gears AND worm gears. What you need is to find the type with the bonded-in rubber seal as these are 0.050" smaller O/D and will give you the extra clearance, you just need to scrape/burn the bonded rubber out to get the thing to fit the end of the AVL crankshaft.

There is also a modification carried out by Tollgate Classics in the UK to fit a 3mm wider crankshaft roller bearing on the timing side, usually for 624 conversions of the 500 C.I. engines!

A.

Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


ace.cafe

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Reply #82 on: April 13, 2019, 09:39:53 am
The thing about Indian mechanics is that they have no clue about theory most of the time, they operate on very strange assumptions sometimes, and surprisingly often (not always), it "works" despite the spurious bases.  Kinda like some elaborate systems of pre-Galilean astronomy... Wrong assumptions but kinda worked as a system.  What I've found is that what these guys lack in basic understanding / book knowledge they sometimes make up for by doing/ seeing every single thing just thousands and thousands of times over, and learning bit by bit what works and what doesn't.  I mean, as one example, they've been clear as anyone here about the weakness in the tappets, and worked out the same solution as people here did, too.  Independently.  My friend was telling me a few days ago how he saw a pristine paint-job being applied at an outdoor parking lot somewhere in the heart of Delhi - this was on an Audi A8 (!), and there was a lot of other high-end machinery all around, too... they certainly don't play by "the" rules, and many of us in the West find this highly irritating... But the average street-mechanic here probably builds more Bullet engines in a year than most U.K.-based specialists would in ten years.  For those who take pride in their work, there's been a lot of knowledge gleaned / applied.  Somehow they keep more Bullets (and other motor vehicles) going than practically any nation on earth. 


Well, I opened the engine today.  You'd have to go back to post#60 for reference re: why. 

Anyway, turned out to be the timing-side main bearing, the small one.

Possibly was a low-quality bearing, the race was toasted and rollers fine.  But almost certainly a contributing factor was the cam spindle.  No time to post a pic right now, but basically the flat on the flange which is supposed to keep it locked against rotating in the case just doesn't match the case very well, there's a big gap - typical crap machining I suppose.  Meaning that the spindle can probably rotate at least 15 degrees in there if the press-fit were a tad loose, which one of mine was.  Wouldn't be a problem with solid spindles (Adrian's choice here was a good one), but with the eccentrics, the trouble is that when you tighten the locknut backlash may be fine, but if in tightening it the whole spindle rotated clockwise in the case, and later at high revs it rotates back anti-clockwise, then all the lash can be gone.  The exhaust cam in this case was so tight I could hardly pry it out.  Which is NOT how I had set it last time.  There's a way to do the adjusting that would mitigate this risk (tighten the eccentric up against the rotation direction, so that if it rotates back, it can only loosen), but somehow I didn't do it that way.  So here we are.  There must have been a lot of radial load on that end of the crank.

The rod big-end seems absolutely fine, so am debating what to do now.  I kinda figure each time you take a crank apart and reassemble, the press-fits get a tad looser, which of course would create its own problems. 

So the hack who did the crank down in Delhi wasn't to blame after all.  He might've done tens of thousands of these (father did it too, he said at the peak they were doing ten per day - that's 3,000 per year, people), and yeah, he got mine to .0015" runout by eyeballing it with a piece of wire (insane).  And he says I'll get at least 30,000km's out of this.  I think he used NRB needles.  Hmmm... 

As mentioned earlier, just no budget for Hitchcock's rod kit, so is it worth tearing it down just to put a fresh pin / rod / Japan bearing in it (or experiment with my own version of Hitchcock's approach), or should I just re-check trueness and throw it back together with good quality mains (and better tappets, and do something about those spindles)?     

Hmmm...

On another note, is there some procedure for setting up the meshing / distance between the crankshaft worm gear and the mating teeth on the oil-pump shaft?  I put a new shaft in 2,000km's ago and it's looking pretty bad already.  Maybe I didn't put a new worm in, can't remember, but it too looks damaged.  I need to check the parts book and see if there's supposed to be a lock-washer or shim or something between the cam pinion gear and the oil-pump worm gear, mine didn't have any.  It seems to me the worm may be running too far inboard, such that only the outermost part of the worm is contacting the shaft's gears.  Any failures here would seem necessarily catastrophic.   

I guess I could just test-assemble with varying thicknesses of washers in between the two, till there's just a little clearance between the worm and the oil seal?  Left-side crankshaft thrust washer would also have an effect on this I suppose (I have the standard size on both sides)? 

-Eric

The oil pump drive spindle gear meshing is set with the thickness of the timing cover gasket. There are different thickness gaskets available.


ringoism

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Reply #83 on: April 15, 2019, 11:41:00 am
   
Add a good sump magnet as protection for the scavenge oil pump chamber and the rocker feed.

Can anyone refer me to a good oil-circuit diagram or description?  I guess this is what they'd call a dry-sump system? I'd worked on cars and two-strokes till now mostly, so never really studied / understood them (nor these three drain plugs).  But am wanting to make sure all's well with the supply to that timing-side bearing.  Also if any enhancements are possible would happily take the time to do them now.

I'll try and get some pics up soon.  Bit curious about this "crescent" that was supposed to be machined into early-vent-system cases.  Mine doesn't have it, but there seems to be quite a lot of empty space in the case casting outside the cylinder sleeve, am thinking I wouldn't need any additional machining.  Oh, and the hole between oil tank and crankcase is a pretty decent size, maybe 8mm? 

-Eric


ace.cafe

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Reply #84 on: April 15, 2019, 04:01:12 pm
Main bearing lubrication is splash-feed, where the oil coming out of the con-rod big end bearing is slung around inside the crankcase, and drips on to the main bearings. Same thing on the 6305. All splash.

If you are feeding oil to the crank, you are also splashing the bearings.

The timing side bearing is the small one with the lowest load rating. If you want a stronger one, you can use a NU 2205 which is 3mm wider. Bearing boss in the case needs to be machined 3mm deeper. Oil drip holes above the bearing boss also need to be deepened accordingly by drilling. I have not done this on an AVL case, but we did it many times in CI cases. You should check the casting for room, or maybe Adrian knows if it can fit there.

The CI hole between oil tank and crankcase is only 3mm. The AVL 8mm hole is because they deleted the crankcase vent on the side, and used the 8mm hole to the oil tank instead.
If I were restoring that to CI specs, I would plug that 8mm hole and re-drill it to 3mm when I added the side crankcase vent system.
« Last Edit: April 16, 2019, 03:08:52 pm by ace.cafe »


ringoism

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Reply #85 on: April 22, 2019, 01:36:59 am
Main bearing lubrication is splash-feed, where the oil coming out of the con-rod big end bearing is slung around inside the crankcase, and drips on to the main bearings.

The timing side bearing is the small one with the lowest load rating. If you want a stronger one, you can use a NU 2205 which is 3mm wider. Bearing boss in the case needs to be machined 3mm deeper... we did it many times in CI cases.

The CI hole between oil tank and crankcase is only 3mm. If I were restoring that [AVL] to CI specs, I would plug that 8mm hole and re-drill it to 3mm when I added the side crankcase vent system.

You've all been extremely helpful, thank you again. 

1.  So are you saying that with the 3mm hole, the aforementioned lack of the timing-side crankcase seal wouldn't be an issue?  Also, any problem retaining the catch-can with this kind of setup (huge amount of dust here isn't going to get along well with continual oil mist out the back)?

2.  (See photos below): With all the dependence on oil splashing around, is there benefit in opening up a bit larger "catch" relief / oil hole in the timing-side casting above the bearing, or otherwise modifying it?  Looks like only so much oil would stream down the inside of the case and find its way into that little recess... I have a mind to make it a little more "funnel" like, perhaps?  And/or maybe to enlarge the entire length of the hole that goes down from there to the bearing.  Anyone done anything to improve it?

3.  When you were machining the deepened bearing recess for the NU2205, was it done on a lathe? (no vertical mills around here, but a bit lathe with a 4-jaw chuck)

-Eric
« Last Edit: April 22, 2019, 11:39:35 am by ringoism »


ace.cafe

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Reply #86 on: April 22, 2019, 04:15:57 pm
My advice would be to obtain a set of CI cases and inspect them closely, and try to duplicate the engine breather and small hole to the oil tank as well as you can.

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.


Adrian II

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Reply #87 on: April 22, 2019, 05:14:26 pm
Quote
Can anyone refer me to a good oil-circuit diagram or description?

From the service manual.



You can see all of the manual here:

http://www.royalenfieldlesite.fr/spip/spip.php?article392

A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


ringoism

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Reply #88 on: April 27, 2019, 09:05:48 am
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
« Last Edit: April 27, 2019, 11:41:39 am by ringoism »


Adrian II

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Reply #89 on: April 27, 2019, 10:05:34 am
I think the philosophy behind the omission of the oil seal behind the timing pinion on the AVL was something along the lines of: "We now have this gear scavenge pump which has a much higher capacity than the old plunger pump, so it will just clear any oil that has wet-sumped before it starts to get past the piston rings." My old Electra-X wet-sumped like anything, but I never had the clouds of smoke problem because it always DID pump the oil out first.

Then along came my fancy AVL hybrid engine based on a set of C.I. Bullet cases which HAVE the timing shaft seal, and which can smoke like cheap burgers on a barbeque on start-up. However as I have done some checks to prove it is not actual wet-sumping, and that th oil pumps are working fine, I'm putting that down to poor oil scraper rings.

Can't see why the old type breather won't work on an AVL any better or worse than on a C.I. Bullet, it only has to do the same job. It's also what the early 350 AVLs had.



I'm sure a catch can will be fine.

Quote
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.

OUCH. :( I hope the insert didn't close up the oil drilling from the sump, I'm guessing you have checked this!

A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...