Author Topic: First AVL ownership/build... tech questions...  (Read 47107 times)

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ace.cafe

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Reply #90 on: April 27, 2019, 04:32:18 pm
If you can get the lathe to work without enlarging the diameter of the bearing seat, then you should be able to use a 2205 bearing. Otherwise, the outer race could spin in the case, causing problems.

Regarding the timing seal, when the crankcase gets pumped down to low pressure, it will suck some oil in through that gap around the crank. I don't know how much will get sucked in. If the gear pumps can clear it, the Maybe there are no worries about it.

But, I would make that hole in the wall to the oil tank smaller, like the CI has, when you make the crankcase side breather arrangement.
The reason being that the hole sizes act as air metering orifices. If the hole to the oil tank is just as large as the crankcase side breather, about half of the air will get pumped into the oil tank, and half out the breather. This causes pumping losses, and also partially pressurizes the oil tank which impedes the evacuation of fumes from the top end.

You need to consider all of the effects on the breathing circuit when making major changes to the design like this. RE clearly didn't, which is why we try to restore it to the old CI breather design.
« Last Edit: April 27, 2019, 04:37:23 pm by ace.cafe »
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Adrian II

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Reply #91 on: April 27, 2019, 05:07:08 pm
The timing side crankshaft seal is 30mm O/D by 20mm I/D by 7mm thick, you can use a 5mm thick one to get the seal further in on the shaft. That's if you're ever letting any more Indian machinists anywhere near your castings.

A.
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ringoism

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Reply #92 on: April 29, 2019, 10:42:46 am
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.

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

A.

yes, thanks, I made sure about that oil passage, it's fine but that was the worst one to have cross-threaded on account of both that and the thinness of the casting there.  A press-in insert would have been better, but these had (coarse) external threads and it was pretty close.

So the early A350 had the old breather AND no crankseal?  If that's the case I'd have no reason for concern.

So anyone have any thoughts on welding the crankpin ends to the counterweights?  In my research seems not generally needed except on very high-powered engines... am just thinking of the abuses mine suffered in the hydraulic press... and its having already been apart twice.  I DO have a truly professional (expat) welder nearby.

It doesn't seem that any compensation for balance re: the weight of welds should be all that tough (saw BW's Youtube vid, lol...!). 

On those lines, my new, modified piston weighs 15g less than the stock one... so should I be re-balancing my crank anyway?

-Eric
« Last Edit: April 30, 2019, 05:52:13 am by ringoism »


ringoism

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Reply #93 on: May 09, 2019, 08:11:59 am


Ah, crap... wrongly thought my big-end axial (thrust) clearance was too small to feel, and didn't measure till now...when I finally felt it... Crank-assembly guy didn't use a feeler gauge, of course, and it's at .635mm and service limit is .65mm... here we go again.

1.  What do the builders out there consider ideal?  Range is 0.20-.55mm new.  Oh, and does anyone think it's a bad idea to assemble the engine with this crank, after having been harshly tweaked for straightness (not phase) in the wrong direction (.010" out - thinking of possible effects to my counterweight holes)?  I suppose BW might be the one to speak to this...

2.  On another note, can RTV or some other sealant be used in lieu of a gasket for the case-halves?  Did it on the cylinder earlier.  I've got plenty of axial clearance on the crank itself, so that's no issue.  We're not getting RE-supplied gaskets here now, the country-made gaskets are horrible, the one in my kit broke in three places...

Everything else is cleaned up nicely, and I hope about ready to assemble...

My NTN C3 main bearings have arrived and are installed in the cases...

CI tappet guides / tappets are in, got new spindles / sleeves in and a set of CI cams to play with.  We'll see how the pushrod lengths all work out and whether I have to notch the piston. 

Now off to the hydraulic press and lathe again...

-Eric

 
« Last Edit: May 09, 2019, 10:14:14 am by ringoism »


Adrian II

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Reply #94 on: May 09, 2019, 02:54:39 pm
When I dismantled my old Electra-X (500 AVL) crankcases there was no gasket between the two halves, just some grey silicone, which I think was the factory method, gaskets being used on the cast iron models.

A.
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ringoism

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Reply #95 on: May 11, 2019, 07:06:53 pm
When I dismantled my old Electra-X (500 AVL) crankcases there was no gasket between the two halves, just some grey silicone, which I think was the factory method, gaskets being used on the cast iron models.

A.

The Electra shop manual I finally found online mentions a gasket, but I went with RTV and expect it'll be fine, thanks.



ringoism

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Reply #96 on: May 16, 2019, 09:03:18 am
Well, it's finally all back together and running well as of two evenings ago. 

After working with my helper on getting the engine/gearbox nicely mounted up in the chassis, cylinder/head/timing cover on and just about ready to finish up, I spent several hours taking it out and opening the crankcase again...

...when I found in my parts box that little ring-spacer that goes between the two drive-side bearings.... dang!  I'd been looking at that thing for weeks, conscious of the fact that it had to go back in there!

So now I've fully opened/re-assembled an AVL Bullet engine thrice, rather than twice...

My helper having departed for home, put the engine/gear back in the chassis and got back to the earlier point by myself this time... I think I strained my back/neck there a bit tho'...

Anyway, managed the old, smaller-base-circle CI cams with standard pushrods, just changed the adjusters (wound out about as far as they can go) to the old style to match the meatier old tappets down there.  Threads were the same.  Plenty-o-piston-to-valve-clearance there despite the higher lift of these cams. 

Spindles/eccentric sleeves are new aftermarket and a significantly snugger fit inside the cams than the original (even brand-new) AVL ones - I'd hoped this would quiet things down a bit, but no, just as clattery as ever when warm - just the nature of the beast, I suppose!

Bottom-end is very quiet vs. before, that timing-side bearing must have been on its way out for quite some time, almost from the beginning it had made noise under load when cold, and had been progressively taking longer and longer to quiet down as the engine warmed up.  That long, full-throttle, uphill run several weeks ago is what had finally finished it / make the source of the noise clear enough (kind of my objective in all the thrashing)! 

Fortunately nothing else damaged in the process.  Rod's got a little side-to-side as gauged from the small-end, manual tells how to measure it but no info re: the limits!  Anyway the big-end axial is towards the tighter end of the spec now vs. the max service limit as assembled by "an expert". 

Crank was trued (by me) to .0008" (.02mm), and the engine feels about as smooth as can be expected from a 500cc Bullet.  Never got an answer on balancing vs. my 15g's lighter piston vs. stock, so just left it. 

Bike's feeling healthy, I'm not in the mood to thrash it just now, I need it to run awhile without major dramas.  Friends coming over in August who want to ride up over the passes (13,500-17,000+ft !), someone or the other will likely be riding this one, so the day for thrashing will surely come.  it's probably been up there dozens of times, just not since I've had it.   

New (old-style) breather setup is done, but not ridden sufficiently as yet to properly assess.  Yes, continuous mist and a little oil spitting out of there, but I've got the OE can to hopefully reclaim most of that, will have to gauge its effectiveness over time.  Honestly I'm dubious about the duckbill's effectiveness as a check-valve... maybe mine's age-hardened?  I might have an easier time finding a proper PCV valve up here vs. a vacuum gauge to verify.  Might also consider a vertical run just out of the crankcase, to help keep any oil-spit down if need be.  As per ACE's advice plugged the 8mm hole between crankcase and oil tank, and drilled a 3mm right near it.  Also made a thin felt washer to go behind the timing pinion, I'd doubt much oil will be passing through there so long as that holds up, maybe even without it.   

Now one question: Should I just plug the original breather port atop the oil tank?  I can feel the pressure pulses there (due to the 3mm hole I guess), but don't see it really serving any purpose now.  Actually have capped it for the time being. 

I'd thought of trying out a 350cc header pipe, but found a calculator online suggesting the existing 1-1/8"ID pipe puts my peak torque around 2,800rpm, where a 1-1/2 would raise that somewhere above 4,000... I guess that's the OD on the 350, not the ID, but still, way down low at 2,800 seems about right for enthusiastic lower-speed street / hill use, so probably will save myself the trouble for now, I suppose it's the revs that are especially hard on everything else and command a lot of the more expensive upgrades anyway.

More later, I suppose there will always be something or the other:  1) I'd like to find a way to achieve a longer intake runner without having to have the filter taking over my (otherwise useful) side-box... and 2) Want to get some side-racks made for carrying fruit baskets (oh yes, I'm serious), as we make/market all-natural jam up here, and at the same time the coming months' tourism rush dictates another sort of "jam" clogging up roads and making arduous work of automobile travel...

For now a hearty thanks to all who've tolerated these ridiculously lengthy inquiries/musings and moreover have responded with repeatedly thoughtful, helpful advice and experiences.  There are a few of you who stand out in particular - you know who you are!

In closing: A friend is up visiting from Delhi who'd never ridden a Bullet... had been scared to, in fact, being they're reportedly so "heavy"!!!  But he took this one out and was surprised to find it so light to the touch and easy to handle - more so than his little 125 Honda, he claims... (I'm going to have to finally get my wife on this thing - the bike was kinda her idea and technically it's hers anyway!).

I had a neighbor's KTM Duke 390 at my disposal during the time the Bullet was apart... a bike I'd thought I was really going to enjoy riding.  The owner had learned to ride on a Bullet Machismo and told me, "wait till you ride the Duke".  Well.  I rode it.  I thrashed it.  Had to, to enjoy it at all - life begins above 5,000rpm's.  I dunno, maybe it's 'cause I'm 50 years old, maybe it's just because a smallish-cc race-tuned bike is pretty impracticable on the street, maybe it's because I didn't have room for my knees - but I just didn't like it. 

So long live the Bullet Machismo...
These are certainly interesting, unique machines, and worth a bit of trouble I suppose.

-Eric





Warm Regards,
Eric


Adrian II

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Reply #97 on: May 16, 2019, 01:54:47 pm
Glad you're pretty much there with this bike at last, you seem to have achieved expert status!

Yeah, ditch the duckbill and get a proper non-return valve, I think would keep the oil tank top vent open too (with another non-return valve) as you still have a small hole into the crankcase, and you have all the stuff coming down from the top end too, all this piles into the oil tank from the timing chest.

A.
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ace.cafe

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Reply #98 on: May 16, 2019, 02:11:51 pm
Good show!

Watch those threaded pushrods adjusters. They bend rather easily when they are adjusted far out. You might put an extra locknut on the bare threaded area, and tighten it up to the pushrod to add support to the long exposed threaded shanks, effectively simulating a longer pushrod. Don't worry about the little bit of added weight.

Don't try to make these engine's valvetrains run quiet. They are supposed to make noise because they are running tappet clearance at the rockers, and they can never be quiet. Any attempts to quiet them will result in damage, even if at takes some time to occur.

Rod side play at the big end bearing should be more than .005" , but less than .020".

IMO, you should leave the oil tank breather plugged now. The breathing circuit relies on low crankcase depression to pull the fumes from the top end down thru the oil tank, so they can be expelled on the downstroke. My feeling is that oil tank venting or any other vent location defeats the designed intent of the breather circuit. That's my 2 cents on that subject.

The duckbill is very low cost, so get a new one If you suspect it might be hardened up. You can use a PCV, but I think the duckbill works better. The very best option(expensive) is the KrankVent. Racers use it.
The oil mist coming out will greatly reduce as the rings get sealed better, by about 500 miles or so.

No need to worry about crank balancing for small changes in mass. A single is inherently unbalanced, and you are only slightly changing the reciprocating mass for the better, by a little bit. It reduces the vertical(primary) vibration component very slightly, and has no effect on the horizontal(secondary) vibration component.
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ringoism

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Reply #99 on: May 20, 2019, 06:14:05 pm
Axial on the big end is about .009" now, down from around .025"!!!

Previous owner of this bike (and about thirty others like it) said he sometimes "lengthened" pushrods with a washer/spacer between the rods and upper ball-ends.  Being press-fit and under compression vs. tension, I guess they're not going anywhere.  Maybe this is something like what Adrian described earlier, and I could turn a couple on the lathe in aluminum easily enough.

Still haven't ridden it crazy-like but it's feeling really strong.  Now if only I could find new washers for the bad, leaking ones at the oil-line banjo bolts...

Friend currently borrowing it for a few days, was hesitant to do so but he's Indian and doesn't seem to take it beyond 1,500revs, so guess we're alright!

-Eric 


ace.cafe

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Reply #100 on: May 20, 2019, 07:05:41 pm
Maybe you can find some soft brass washers for the banjos, if you can't find copper.

I have successfully used brass washers in the banjos.
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Adrian II

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Reply #101 on: May 21, 2019, 12:15:29 pm
Quote
but he's Indian and doesn't seem to take it beyond 1,500revs

Just so long as he doesn't try and lug the engine in higher gears, that's not big-end friendly.

I'm toying with the idea of making my own push-rods from solid 10mm ally rod, taken down to 9.7mm at the bottom and threaded for 1/8" BSPP hex blanking caps for adjuster use, with stud and bearing grade Loctite keeping it all in place, then drill and tap these 1/4" BSC for the iron barrel tappet adjusters. The tops could be drilled and tapped 6mm if the AVL tappet adjuster ball ends aren't too big to fit the AVL rockers.  1/8" BSPP is a fairly fine thread.

A.
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ringoism

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Reply #102 on: August 01, 2019, 07:53:25 pm
I'm toying with the idea of making my own push-rods from solid 10mm ally rod, taken down to 9.7mm at the bottom and threaded for 1/8" BSPP hex blanking caps for adjuster use, with stud and bearing grade Loctite keeping it all in place, then drill and tap these 1/4" BSC for the iron barrel tappet adjusters. The tops could be drilled and tapped 6mm if the AVL tappet adjuster ball ends aren't too big to fit the AVL rockers.  1/8" BSPP is a fairly fine thread.

A.

I haven't checked the forum for a couple months I guess.  Interesting, I just modded my pushrods today, maybe something not unlike what you're outlining here.  They had seemed a weak link to me especially being so far wound out, despite my having put spacers over the threads 'twixt the locknut and pushrod to help strengthen that rather spindly thread on the (late CI, metric) adjuster  cup, one of which was already bent slightly (it was a second-hand piece I'd put in "temporarily").  As noted earlier, I still had a lot of valvetrain noise of uncertain origin, and it's been seriously irritating my tinnitus.  Today that was solved, maybe partly as a function of having both my adjusters actually straight.

Other possible noise source: A few weeks ago had the timing cover off and observed that cam gear backlash was not consistent from one point of rotation to another (yes, had the pushrods out, so fully unloaded).  When I'd set them correctly at their point of tightest interference, then at other points the gears meshed loose enough to likely be causing some of my rattle.  Wasn't sure if this was due to wear (they were a used set of CI cams I'd just been experimenting with), or (more likely) poor machining on RE's part.  The new OE ones I put in today are still not perfect in this regard (so it probably is the machining more than wear), but they seem better than those I had in there.  I've still got more backlash on one side of the gear than the other, but not too bad.   

Also noted that even when pushrods are set to zero clearance cold, they become really loose when hot.  I mean, REALLY loose.  Which means the cylinder/head are expanding a lot more than the pushrods, despite both being aluminum.  This seems a curious thing that I guess can only be indicative of temperature differences amongst components.  Short of fitting a CI cylinder block or finding a pushrod material with a much higher coefficient of thermal expansion (not likely), the quest for a quiet AVL might end here, I thought.   
 
Anyway, what I ultimately did was found a set of old CI pushrods with the 1/4-28 adjuster threads, these are substantially beefier than the M6's on late CI's / AVL's.  So I figured that would largely eliminate the possibility of bending.  Only trouble being that CI pushrods are hollow and without fabricating a bushing (not a lathe owner at present), the ID is too large to provide the needed press-fit for the little spherical steel nib from the AVL pushrod's top end.  And I think there were problems on the early AVL's with pushrods bending - I'm going to guess in the hollow design being carried over from the CI's.  Other problem is that the ID of the CI adjuster assembly, where it press-fits onto the machined OD of the pushrod, is larger.  So no press-fit available there, either. 

So here's what I did: Removed the complete adjuster from the old-model CI pushrod.  Removed the steel nib from the AVL pushrod top-end.  Inverted the AVL pushrod.  Drilled out the threaded (originally bottom) end of the pushrod sufficient to provide the press-fit for the nib, and pressed it in.  On the other (originally top) end, I drilled out the original nib-hole to 1/4" to allow clearance for the new, larger adjuster threads, then pressed the complete adjuster assembly on that end.  Depending on the particular pushrod's OD, it may or may not press-fit directly - my original pushrods were a perfect OD for it.  If the pushrods' OD is too large (like my RE replacements), the OD can be turned down slightly (mount rod in hand drill and use flat-file/emery cloth) to provide the proper press-fit. 
 
So basically I've got upside-down solid aluminum AVL push-rods with AVL top nibs and the beefy old-model 1/4-28 adjuster cups.  In my case I also shortened my pushrods by a few mm's to allow for enough adjustment, but that's mainly because my cylinder was shortened by 2.5mm.  This would not be necessary for everyone. 

As outlined earlier, I had installed the larger-diameter CI tappets at the time of my last rebuild, and now with the stronger adjusters, I'm feeling much confident about valvetrain reliability now.  Besides tappet feet sometimes breaking off, the AVL's were known (here in India at least) to "throw" the pushrods, meaning they'd sometimes fall out of the fairly shallow little sockets in the OE AVL tappets. 

Only possible downside in all this is that everything's now a LOT heavier than stock.  I've got CI tappets which are a LOT heavier than the AVL's.  I've got solid AVL pushrods which are a LOT heavier than the hollow CI's.  And I've got the old-version CI adjuster assemblies which are a LOT heavier than the AVL's tiny bits.  If I were building something with the idea of high-revs, I'd turn down / eliminate whatever I could on the adjusters to lose some weight there, or else drill/tap the original AVL hardware, which is a lot smaller/lighter, to accept the 1/4-28 cups.  And I'd probably go with the tubular pushrods, too, all in the interest of avoiding valve-float.  For my intended rpm range, I don't expect problems.   

Bike's been running really great, really strong, about as much power as I feel I would ever need with local roads in view, extremely responsive and certainly pulls a fair bit harder than a stock AVL, that across the entire rev range.  I've still not really revved it near redline (whatever that is), mainly because I actually don't need to in order to move along briskly, also because I've got this extra power working on a stock crank and don't really want to push the limits till I've at least got some good use out of the bike.  I figure a year from now I might be in the mood to pull it all apart again... and if so will do the crankpin and bearing up better. 

For now, might change the oil and then am hoping to just ride it for some months with minimal fiddling.  If my warmup and short ride home this evening were any indication, it's quieter than it has ever been, quieter even than some of the hydraulic-lifter UCE's I hear running around.  Probably going to take it out to Lahaul/Spiti valleys with some riding buddies in a couple weeks.  Only a measly little 13,500ft pass between here and there (I'm sure the bike has been above 18,000 more than once before I owned it), lol. 

-Eric
 
« Last Edit: August 01, 2019, 07:59:53 pm by ringoism »


ace.cafe

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Reply #103 on: August 01, 2019, 08:34:58 pm
Avoid all temptation to make it quiet. It was designed and always intended to be noisy. If it's quiet, something is certain to go wrong.

Regarding the pushrods hot clearance, it is doing exactly what it is supposed to do. That is called valve lash, and all flat tappet valvetrains require it for proper running. Zero clearance cold yields about .012" clearance hot, and that is how it is designed. Do not try to circumvent that.

Regarding cam gears being somewhat eccentric, welcome to royal enfield. You might find a set that are better, or put two cams from different sets together to make a good set, but it may take some looking around.

My suggestion is to get accustomed to the sounds of the engine and enjoy the bike.
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ringoism

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Reply #104 on: August 02, 2019, 05:29:17 pm
Yeah, thanks ACE, I read your comments earlier re: noise, and understand about valve-lash, etc.  But observe a fleet of thirty identical bikes all maintained by the same mechanic for ten years, and you do find some that are relatively quieter than others.  Note that I used the word "quieter" vs "quiet" which certainly cannot be expected (and the UCE's here have a lot of issues with loose/defective hydraulic tappet, some being replaced under warranty on near-new bikes.  These days dozens and sometimes hundreds of UCE's, along with a handful of AVL's / CI's go past daily fifteen feet from our door, so I have opportunity to hear the full range.  My AVL had what I could safely call an abnormally nasty clatter only in one specific rpm range, outside which it was just sort of the normal ticking noises I could easily bear with and even appreciate for its mechanical "honesty". 

Regarding valve clearance, I know it is necessary but it is also clear that Iron blocks expand less than aluminum, and being that these also call for zero lash cold, they obviously run with less lash hot than do the AVL's (hence are quieter and still safe!).

My theory re: my particular noise problem was that within that particular rpm range, when on the downramp of the cam lobe, the valvespring tension was actually accelerating the cam against whatever backlash existed.  Exacerbated by the problem of not being able to set backlash properly on account of the gears' unintended eccentricity.  At higher rpm's, inertia took over and the slight acceleration/deceleration of the cam disappeared, the backlash becoming immaterial and things becoming quieter. 

Having said all this, I wouldn't bother at all except for my persistent and easily irritated tinnitus (had it since childhood)... two months away from the bike last winter and it had nearly disappeared, back on it for less then ten miles and it was back with a vengeance (earplugs only help a bit with particular frequencies).  End of the day, I don't have the tappets or cams set overly tight, and new RE cams only cost me under $30, so it seemed worth the cost in time/effort.

)Eric
« Last Edit: August 02, 2019, 06:15:40 pm by ringoism »