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Author Topic: First AVL ownership/build... tech questions...  (Read 3640 times)

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Adrian II

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Reply #15 on: April 02, 2018, 05:30:17 pm
Sorry I can't advise on oversize piston rings, oversizes have only recently become available for the UCE models here and I don't think +.030" is a size we have. The 87mm piston doesn't count!

That small bore inner pipe in the exhaust header is meant to be there as part of the Lean Burn set-up by which the AVL models were touted as being more eco-friendly. I gather other people have succeeded in removing it, but you might be able to adapt an I.B. pipe if you can't get the Hitchcocks' unrestricted pipe from the UK.

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 #16 on: April 02, 2018, 06:25:34 pm
If you are okay with the current top speed,  then you could keep the small ID header for torque. A bigger header ID will lose low rpm torque.
Your best bets are displacement and compression. If you want to adjust cams, go with the advanced timing g pinion.


Bullet Whisperer

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Reply #17 on: April 03, 2018, 03:46:58 am
Great care must be taken if advancing the inlet cam - the inlet valve gets very close to the piston crown on standard timing and this is one of the reasons I have retarded the 'S type' inlet cams by 1 tooth from the marks on some Electra X engines I have tuned.
 Here is one such machine, with shortened barrel, 'S' cams [inlet retarded] and Amal carb going about its business. The first machine I tuned gained bottom, mid range and top end power as carb sizes increased from 32 to 34 and finally, 36mm. It ran 19/38t gearing [with 18" rear wheel] and went like stink, from idle to flat out at 103 mph. The one in this video will do well over 90 mph.
 B.W.

 https://youtu.be/obBjjB4nPiw


ace.cafe

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Reply #18 on: April 03, 2018, 06:39:26 am
Great care must be taken if advancing the inlet cam - the inlet valve gets very close to the piston crown on standard timing and this is one of the reasons I have retarded the 'S type' inlet cams by 1 tooth from the marks on some Electra X engines I have tuned.
 Here is one such machine, with shortened barrel, 'S' cams [inlet retarded] and Amal carb going about its business. The first machine I tuned gained bottom, mid range and top end power as carb sizes increased from 32 to 34 and finally, 36mm. It ran 19/38t gearing [with 18" rear wheel] and went like stink, from idle to flat out at 103 mph. The one in this video will do well over 90 mph.
 B.W.

 https://youtu.be/obBjjB4nPiw
Good point, B.W.

I neglected to mention the piston/valve concern.

On the few AVLs that we have done, we were able to do the squish mod with 1.8" inlet valve, and stock cams, and still have .032" piston /valve clearance, which admittedly is closer than I would normally recommend.  Advancing the cams in that situation would be  out of the question unless a valve relief was cut into the piston.


ERC

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Reply #19 on: April 05, 2018, 08:24:59 am
Great care must be taken if advancing the inlet cam - the inlet valve gets very close to the piston crown on standard timing and this is one of the reasons I have retarded the 'S type' inlet cams by 1 tooth from the marks on some Electra X engines I have tuned.
 Here is one such machine, with shortened barrel, 'S' cams [inlet retarded] and Amal carb going about its business. The first machine I tuned gained bottom, mid range and top end power as carb sizes increased from 32 to 34 and finally, 36mm. It ran 19/38t gearing [with 18" rear wheel] and went like stink, from idle to flat out at 103 mph. The one in this video will do well over 90 mph.
 B.W.

 https://youtu.be/obBjjB4nPiw
      Neat video, I wonder who trims all those hedges along the roads. Could be a money maker for landscapers.
2-57 Apaches, 2-57 Trailblazers, 60 Chief, 65 Interceptor, 2004 Bullet, 612 Bullet chopped.


ringoism

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Reply #20 on: April 06, 2018, 08:00:53 am
Adrian: I think what most people have succeeded in removing is actually the "hot-tube" in the last six inches or so of the header pipe, that being a tiny 3/4" ID.  Done that.  But even if it were possible to remove the entire inner pipe in the bent area (can't imagine how), on Indian headers you'd still have a restricted area the first couple inches from the port, where even the OD is stepped down to maybe 1-1/4". 

ACE: I really appreciate your time/perspective as an experienced and pretty distinguished tuner.  Could you refer me to a good calculator for intake tract / header lengths/diameters?  Really would like to optimize this eventually, if possible.

BW: Thanks for that video and other inputs.  You may know that in India you would be respectfully addressed as "Guru-Ji" - your exploits have clearly raised you to that status and having now watched a few of your YT videos, am really appreciating the kind of simple, grassroots approach to things you've taken (seriously, a socket/extension hung in the crankpin hole for balancing...???  A propane torch for gas flow???  I love it!!!  And it works???!!!). 

So thanks again fellas.  Great info / insights here. 

Mmmm… so retain/enhance the typical low-end torquer Bullet attitude via advancing the cam, keeping the small header - or else bump up the midrange by maybe retarding the cam, bolting on my BS32 carb and a modded CI350 pipe…  Neither option will cost me much apart from a little time, and I can wait to finalize.  Will first try it “as is” (basically just the compression/squish mod, hot pipe removal and very minor port/head work), break it in a bit, and see what I’m most inclined towards.  We hardly have opportunity to ride above about 50mph up here, and torque is a boon on hairpins / inclines, but still, a strong midrange “ramp” has always held a certain satisfaction and is useful in its own way (and a little easier on drivetrain components maybe).   Let’s see.   

Speaking of drivetrain, I had the gearbox apart a few days back – not too bad a job though getting the whole assembly back in the case in one go – specially with regard to the selector disc - is slightly tricky and required the help of our own local shop "Ustaad" ("master" - incidentally the one who had insisted that these gearboxes never go bad???).  As suspected the engagement “dogs” on a couple gears were looking a little more trapezoidal vs. castellated (if that makes sense) - this did not seem to impress him much.  Anyway, apparently too many inexperienced bikers over too many years on an unfamiliar bike making countless gear changes heading up 17,000+ft. passes, and missing a few here and there.  With no new gears on hand and a little past success with a grinder / diamond files, I worked a prime example of Indian “juggad” that may actually work (am sincerely hoping so).  Also replaced the indexing pawl spring, which seemed a little weak vs. the new one I was fortunate enough to find (its significance likewise lost on ustaad-ji).   

The engine is mostly together as of yesterday, and re-mounted in the chassis.  Bought another new piston kit to provide for my broken ring – cheap enough here, and hope eventually to find the ring set sold alone to use on the extra piston / some future project.  Turns out the old CI ring is 1/16” (.0625) thick, vs. the AVL’s 1.5mm (.059”), so that’s not gonna work unless I alter the ring groove.  There are just so few of these 500LB’s over here country-wide, and the quality of re-boring work has been so poor for so long that most people learned the hard way to install complete new standard-sized kits (even at ten times the price).  In my case, really had to sit there and insist on the guy putting my cylinder back in the honing machine (three times!) to get the clearance right.  Little understanding colloquially that the larger the piston/bore, the more expansion you’re going to get / more clearance you’ll need.  Any attempts at illuminating the average third-generation technician here and the response is usually, "You know the theory, we know practically".  Some truth in it, but what I do know very practically is that the cylinders they bore end up with seized pistons extremely regularly (read the Indian forums and it's every Bulleteer's greatest fear) - Short of light trucks, this is about the biggest piston in India and they try to set it up the same way they would a moped’s (which they also set too tight, in the pursuit of "long life").  Anyway.  This has been quite a process. 

In truth the crank was not really done to my satisfaction either (old pin retained, with oversized NRB rollers and the typical honing out of the rod, another multi-gen guy here claiming - rightly - that the RE-supplied pins were junk and as mine (made here by MACO) was in good shape it was probably safer to just leave it in place).  Their date-mark was stamped on the crank from when they'd done it in 2011, and if it would do another 6-7 seasons of riding over the passes I'd be reasonably satisfied - but there are signs (to me) that the pin, even if hard enough, wasn't entirely round... oh, brother...

Admittedly he got the crank assembled fairly straight (at least a lot better than some of the RE factory's work - BW's related YT video illuminating here) even without a dial indicator (never seen one used in a crank shop here).  I'd brought one along and he was willing to humor me...  0.04mm runout, the published spec being 0.08mm max... Says I should expect 25,000mi out of this, let's see.  Would've liked better, wish they'd have cleaned out the oil passages with fresh solvent - but they know everything and have been at it for years, and the gracious friend transporting me and my 10kg crank had been waiting a long while for us to get done...  Hope I will not be facing any regrets too soon.  Anyway, these are the pains of trying to do a decent quality build in the AVL's land of origin.   

Squish seems to have worked out, as the squished whole-wheat lump suggests.  Eliminated the 0.5mm cylinder base gasket in favor of high-temp RTV, but had to re-surface the cases a bit (emery cloth, a thick slab of plate glass, and patience - the traditional Indian way), which were not very nicely matched (cylinder rocked on them) and moreover badly scarred by whichever previous hack mechanic.  Managed to find a head gasket that was around 0.3mm thinner than others in the stack of genuine RE ones I checked (one plus side to the OE’s large manufacturing inconsistencies).  Long story short I seem to be just shy of 1mm squish. 

With stock cam timing (should check advanced also), valves seem surprisingly to be coming nowhere near the piston despite its topping out a bit above the deck now – maybe in part because I didn’t replace the valve seats but re-cut/ground them, raising everything a fraction.  Or maybe because my particular inlet cam was factory-retarded?  I could make up a degree-wheel but feeling I've got a lot of time in this already, want to get it basically running. 

Waiting on assembling the primary drive for lack of an elusive rubber seal (the slim one between the gearbox input/output shafts).  Supposed to be one coming up from Delhi.  And on the flip side are the cam spindle sleeves, which are badly worn (should’ve noticed it earlier) – bought new ones an hour away from here that must be (CI) imperial-sized, because while a perfect fit inside the cams themselves, they won’t slide over the studs in the case, being a fraction smaller in ID.  Some difficulties / delays ordering stuff here in the greater Himalayas, the internet / mail order are not really developed for motorcycle spares and you kind of need a friendly local parts-man on your side, who doesn’t mind wasting his time on your petty desires (thus far at least one is tolerating me).  And as I said earlier, even in Delhi I think the AVL spares are getting sparse.  By Indian law RE is supposed to supply them for 15 (10?) years from the date of manufacture, but that is almost always violated by all the vehicle-makers.   

Thanks again to all for the help, I hope to have this thing fired up by Monday afternoon, and just hoping/praying it all fundamentally “works” and will be making all the right noises.   

-Eric


ringoism

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Reply #21 on: April 06, 2018, 09:11:53 am
P.S.:

Forgot to mention: adjustments wound almost all the way down, my pushrods were just barely short enough to cope with the approx. 2.5mm shaved from the cylinder bottom, and the elimination of the base gasket, and the valve stem ends being a little higher on account of the re-machined seats (and this is with a 1.5mm thick head gasket).  Looks like it'll work.  But just FYI for anyone else doing a similar compression mod, 2.5-3mm seems about the max do-able in terms of stock pushrods. 

And re: cam timing, still wanted to get this straight:  40 teeth / 360degrees = 9 degrees of cam rotation - but that's only 4-1/2 of crank rotation... which I thought is what we were working off when speaking of valve timing.  And our host's adjustable pinion (which I still can't find on the site) is supposed to be 4-1/2 degrees fore/aft... in which case, wouldn't that be the same as one tooth? 

Bit confused here.

Eric


ringoism

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Reply #22 on: April 06, 2018, 09:43:11 am
Oops...  crank degrees double the cam, right...?  So 18degrees either side when advancing / retarding a tooth.  That's quite a lot actually, and I could see where the result could be considerable, maybe excessive even, depending how much (and to which side) one's particular cam varies from OE spec. 

I need to rest my brain, apparently.
-Eric


ace.cafe

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Reply #23 on: April 06, 2018, 12:27:20 pm
Oops...  crank degrees double the cam, right...?  So 18degrees either side when advancing / retarding a tooth.  That's quite a lot actually, and I could see where the result could be considerable, maybe excessive even, depending how much (and to which side) one's particular cam varies from OE spec. 

I need to rest my brain, apparently.
-Eric
Yes, it is 18 crank degrees.  I think it can be a good choice to relieve the piston for valve clearance for a goal of low-mid torque.


Adrian II

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Reply #24 on: April 06, 2018, 05:49:13 pm
Eric,

sorry, forgot to mention that the ends of the adjustable cam spindles (the circular nuts with the spanner flats) are 15mm diameter where they sit in the AVL timing cover. The I.B. spindles are 5/8" or 15.88mm all the way along, so yes, you will need a 5/8" reamer or drill in the timing cover where it sits over the cam spindles if you swap to solid spindles.

One other thing I have noticed on all the 500 AVL heads I have seen is that the outer edges of the valve seats actually protrude into the combustion chamber by about 1mm. Cutting the seats back so that the outer edges are flush with the combustion chamber will give you a little more piston to valve clearance, though it sounds like you might already have done this.

A.

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


DanB

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Reply #25 on: April 06, 2018, 11:45:06 pm
Cool build and great narration. Looking forward to the next installment.
Suppose I were an idiot, and suppose I were a member of Congress; but I repeat myself. ... Mark Twain
2006 AVL Electra


ringoism

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Reply #26 on: April 10, 2018, 08:54:03 am
Anyone have any advice for me re: initial startup after rebuilding?  All's ready for tomorrow morning (Indian Standard Time).

When I used to start up freshly refitted engines in cars the main concern was oil pressure, making sure it builds before too long.  Mechanic here says on Enfields it can take a LONG time to show up at the banjo bolts on the head... I don't see why it should take so long, but anyway main concern is the crank/piston - is there any way to know that oil's arrived there?  Despite having read a description, the lubrication system is still a little confusing to me. 

Also just advice re: initial run-in... I'm going to assume my re-bore isn't extremely round, nor is it set up very tight.  Top ring is chrome, scraper is cast-iron.  Crank is re-done and fairly tight clearances there.

I've rebuilt a lot of engines, but all were either V-8's or two-strokes, also one 2.5L wet-sleeve diesel. 

Though basics are the same, this somehow seems like a different animal... and I confess I'm struggling a bit despite taking at least ten times as long to do this as the average Indian street mechanic...

Thanks,
Eric


tooseevee

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Reply #27 on: April 10, 2018, 09:58:20 am
Anyone have any advice for me re: initial startup after rebuilding?  All's ready for tomorrow morning (Indian Standard Time).

When I used to start up freshly refitted engines in cars the main concern was oil pressure, making sure it builds before too long.  Mechanic here says on Enfields it can take a LONG time to show up at the banjo bolts on the head... I don't see why it should take so long, but anyway main concern is the crank/piston - is there any way to know that oil's arrived there?  Despite having read a description, the lubrication system is still a little confusing to me. 
Thanks,
Eric

           The engine work on my '08 was not as extensive as yours. It consisted mainly of headwork by Ace and Mondello's, but it was not run at all for over a year all the same.

           All I did was leave the banjos loose while I kicked it over. IIRC it took about a dozen kicks to have oil oozing out. If you prelubed everything, as I'm sure you did, it should be fine. Look how horribly these engines are treated in India and they keep plugging along. I think thousands of them run for years with just barely enough oil and maintenance to keep them gasping and struggling along. AND with a 400 RPM idle they seem to love in India.
« Last Edit: April 10, 2018, 10:16:15 am by tooseevee »
2008 AVL Classic.Extensive head work by Ace.Ace canister/TM32/Ace manifold.Small open bottle/hot tube removed.Pertronix Coil.Bobber seat.Fed mandates removed.Battery in right side case.Decomp&all doodads removed.'30s Lucas taillight/7" headlight.


ringoism

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Reply #28 on: April 11, 2018, 04:31:35 am
. Look how horribly these engines are treated in India and they keep plugging along. I think thousands of them run for years with just barely enough oil and maintenance to keep them gasping and struggling along. AND with a 400 RPM idle they seem to love in India.

Well, I did pre-lube everything... just this slight concern that maybe I forgot something / got something together wrong (couple earlier oversights were caught).  I wasn't very careful disassembling because I believed I'd have professional oversight at the point of re-assembly (ultimately very infrequently!). 

You've got a point about the treatment of Indian Bullets (though 400rpm sounds on the high side... :) )

The one here in the photo just came back yesterday from a tour of Kinnaur/Spiti valleys - very rugged, remote places.  I'd spent a few hours astride this bike just before that; feels like brand-new to ride it - powerful, quiet innards, steering, suspension, brakes, gears spot-on and even good tread on the tires - despite its presumably being subjected to this sort of treatment pretty regularly.  One part of me wishes I'd been able to buy this one instead of mine... Would've been a lot less work, though doing it this way I've received a pretty extensive education (just hope it works). 

Snowed unexpectedly this morning so the workshop wasn't really open / in operation. 

Tomorrow...

-Eric

 


ringoism

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Reply #29 on: April 11, 2018, 04:54:27 am
Exhaust header pipes - The iron barrel 350s use a 1.5" outside diameter pipe, the 500s use 1.75".

There is a school of thought that an unrestricted 1.75" pipe is actually too much for a 500 Bullet. In the UK there was a classic bike dealership that raced Indian built iron barrel 500 Bullets in the 1990s, one of their tuning tricks was to fit the 1.5" header pipe off a 350 to speed up the exhaust gases.

Thanks for the tip - Yes, everything I'm reading online suggests that 1.75" would be quite oversized for a 30-50hp engine.  Even a 1.5" is supposed to be able to support up to 80hp according to one source. 

Rpm at torque peak reduces by some few hundreds per 1/8" of pipe diameter apparently.  So in the low-down-thumping, fuel-economy-obsessed Indian context, a 1-1/8" header ID probably made good sense; This squares with what ACE has been saying,  though the old iron 500's with their "oversized" pipes didn't seem to run badly either, and I could wonder if something this small is overdoing it.

I'll see how it works now that the port is matched, the tiny 3/4-ID "hot-tube" (wonder what that thing actually is) removed, and a thinner-section gasket that doesn't block the path is installed. 

I did wonder whether whatever smaller-diameter header ID ideally should actually be extended some instead of opening up into 1.5+ after the bend.  V-8 headers seem to often be of 30" or more in primary tube length, but in multi's there are other considerations of course. 

-Eric