Author Topic: First AVL ownership/build... tech questions...  (Read 5642 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
Quote
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 »