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