Question 1

Why pay for a PDF when free forum threads already exist?

Accepted Answer

Forum threads go dead. Links rot, images age out of hosts, and the three-page "I think it's the points" thread that solved your exact problem disappears when the poster deletes their account. IronHead PDFs are a reproducible reference you file in the garage and re-open every time: spec bands quoted with tolerance numbers, year-by-year diff matrices for every variant of the model, the diagnostic matrix riders actually hit, and the OEM + aftermarket parts-sourcing sheet per system. A forum thread wins if you have a single freak symptom and a thread originator with the same one. It loses when you need a spec band you can quote at the bench.

Question 2

How do you source the specs — are they actually accurate?

Accepted Answer

OEM-first. Every spec starts at the factory service manual — the document the dealership printed the year your bike left the line — and the tolerance bands published there stay the primary number on the page. Aftermarket second: where the OEM spec is missing or known-bad, we cross-check to named suppliers per system (Keihin 30 mm → 31 mm progression, Amal Concentric, Linkert M74, Ignitech ignition modules per era) and call out the provenance inline so you can quote the source at the bench. Spec bands aren't feel numbers. They have units, a year-and-variant tie, and a citation row in the year-by-year diff matrix at the back of every guide — the same matrix that lets a 1974 Norton and a 1977 Norton sit on the same bench without pretending they're the same bike.

Question 3

Is this generic, or built for the bike I actually own?

Accepted Answer

Every guide is scoped to a single model family. CB750 covers K0 through K8 only, with the points-to-coil ignition transition and the cam-chain uprate called out at the right year. Bonneville covers T120 / T140 plus the N1 (1969) and S1 (1970) sub-slugs year-by-year. Norton Commando covers the 750 and 850 across the Isolastic cradle-frame era — the 1974 and 1977 frames do not share a spec band and the guide says so. Indian Scout / Chief maps the 1927-1971 line (Scout 37, Sport Scout, Sport Solo, NAMI 999-Series) and the Chief separately. Harley folds Ironhead, Panhead, and Shovelhead into one bundle with year-by-year diff blocks for each. BMW Airhead folds /5, /6, and /7 into one PDF with the bore progression called out. There is no "vintage motorcycles" generic — every model code on the cover page is in there.

Question 4

What do I actually get when I buy a guide?

Accepted Answer

A sequenced build manual — not a parts catalog, not a forum write-up. Each PDF carries 40 to 80+ ordered procedures and 70 to 96 factory tolerance bands: pre-restoration inspection, top-end teardown, ignition service (points → Rita → TCI → CDI per generation), carb rebuild (Linkert M74 / Keihin 30 mm → 31 mm / Amal Concentric / Mikuni BS-side per model), harness walk-through, clutch and primary drive, lubrication, electrical, and the final start-up sequence. The spec bands apply before you turn a bolt (basket-case Sportster: know the tolerance before you spend the first receipt) and after — the diagnostic matrix at the back covers what riders hit on the road once the build is rolling. Year-by-year diff blocks call out the spec bands that changed mid-run — 1963 mid-year Panhead intake, 1977 /6 → /7 ignition swap, 1982 Custom TCI step on the CB650, 1999-2001 IMCA Mikuni HSR42 retirement — and the back-of-book parts-sourcing sheet is OEM-first, aftermarket-second, with named suppliers per system so the receipt list is half-written before you order.

Question 5

Is there a money-back guarantee?

Accepted Answer

Yes. Reply to the purchase email within 30 days and the guide goes back for a full refund — no restocking fee, no "we'll review the case" form, no back-and-forth about why. If the PDF doesn't earn its bench slot in the first month of use, it doesn't earn your money. Start the claim at /contact and the refund routes the same day.

Question 6

What format is the guide in, and which devices can I read it on?

Accepted Answer

PDF — fixed-layout, paginated, downloadable. File size lands in the 40-90 MB band because every wiring diagram and torque table is rendered at a printable resolution rather than compressed for in-browser scroll; this is deliberate, because the bench reference needs to lay open on a printed page next to the bike. Offline-first: once the file is on your device, no network connection is required to read it. Supported readers cover the universal set — macOS Preview, Acrobat Reader, the iOS Books app, any Android PDF reader, and the Kindle app via Send-to-Kindle — so the bench tablet, the shop laptop, and the phone all open the same file. Unlimited re-downloads from the purchase email link, any time, any device. Printable at home (US Letter or A4) or at a shop — the diagrams hold detail at 11×17 if your bench has a wide-format printer.

Question 7

Do you actually cover the bike in my garage — every variant, every year?

Accepted Answer

Yes, across 25 canonical model lines and the deeper slug set that splits them where the model changed mid-run. The catalog covers Honda SOHC fours (CB750 K0-K8, CB550, CB650, CB450, CB350, CB900F), Triumph twins (Bonneville T120/T140 plus the 1969 N1 and 1970 S1 sub-slugs), Norton Commando 750/850 across the Isolastic era, Indian Scout/Chief (1927-1971 including Scout 37, Sport Scout, Sport Solo, the 1999-2003 IMCA reissue, and Chief through the 2002-2003 Blackhawk), Harley-Davidson Ironhead / Panhead / Shovelhead bundles, BMW Airhead /5-/6-/7 with the bore progression called out, Moto Guzzi V-Twin (1967-1985 small-block and 1971-1980 big-block), Ducati bevel-drive, BSA A-series / B-series / A50-A65, plus the Japanese UJM twins/Multis (Suzuki T500/GT, Suzuki GS750, GS1000, Yamaha XS650/XS750/XS850/XS1100, Kawasaki Z1, KZ1000). Variant diff blocks sit inside each model PDF — a 1974 Norton Commando does not share the Isolastic spec band of a 1977, and the guide says so on the page where the bench would otherwise guess.

Question 8

Will I get updates if the guide is revised later, and can I re-download it?

Accepted Answer

Yes to both. Lifetime free re-downloads from the purchase email link — re-pull the file from the same link any time you change devices or your old laptop retires, no expiry. Every revised edition is automatically delivered to existing buyers via the same email link (no extra purchase, no surcharge, no subscription to renew or cancel — there is nothing for you to forget to renew because there is no renewal). Major revisions — new tolerance bands discovered during the next shop cycle, new recall coverage, mid-run year-range tweaks, additional aftermarket supplier citations — ship at least quarterly; minor corrections (typo fixes, a single torque line in a year-diff table) ship as needed. The buyer email log is durable on the system that issued your original purchase confirmation, so do not delete that thread — without it, support has to fall back to the order ID lookup which works but takes an extra round-trip.

Question 9

Where do the wiring diagrams come from — are they just trace-and-color copies of forums?

Accepted Answer

The harness topology is sourced from the factory service manual first. Connector-pin tables are quoted inline with the OEM document section that publishes them — every pin in the loom carries the factory service manual citation next to it on the diagram. Color codes are reconciled against the year-and-variant wiring harness page at the back of the book, so the wire labelled "white/red" on a 1975 loom maps to the right terminal on a 1978 loom (Honda changed the stripe mid-run on some circuits; the diff row says when). Aftermarket-circuit deviations are tabled separately with the supplier named inline — Ignitech TCI-series ignition retrofits, Rita ignition swaps, Podtronics rectifier/regulator rewires, and the like — because they change the wiring path and we do not want a forum-trained color guess standing in for the OEM source. Each wire in the diagram has a color, a gauge, a connector part, and a quoted service-manual page number — the same row that lets you quote the source on the bench if a buyer ever asks where the spec came from.

Question 10

What sat behind the torque values in the book — are they feel-good numbers?

Accepted Answer

Every torque value is sourced to the factory service manual as the primary number, with units called out (N·m first, ft-lb in parentheses next to it, because most American benches still read ft-lb on the beam). The fastener grade, thread pitch, and whether the bolt is plated vs unplated appear next to the number — a grade-8 bolt, a grade-5 bolt, and a stainless replacement of the same thread take three different torque values and the matrix says so. Fastener-grade tables sit at the back of every PDF so a 1972 Norton and a 1976 Norton can sit on the same bench without one torque value being misquoted to the other frame. Where aftermarket assemblies demand a deviating number — Carrillo rod bolts, ARP head bolts, aftermarket head studs from Kibblewhite or equiv — the spec is named per supplier with the citation row sitting in the year-by-year diff matrix, not buried in a footnote where the bench will lose it. If a torque spec is missing for your exact year, the citation row explains why; the section is more citation than prose so the bench reads the source, not the bench reads us.

Question 11

How was the new model-history section produced?

Accepted Answer

Each model-history writeup draws on four sources, cross-checked before publication. First, the factory service manual’s introduction chapter — the chapter the marque’s own engineers wrote when the model went into production. Second, marque-published production records: Triumph Meriden works records for the pre-unit and unit-construction Bonneville lines; Norton AMC-era production ledgers for the Commando cradle-frame years; Indian factory books through the 1953 reorganization plus AMI/IMCA continuation records to the 1971 Scout end; BMW Motorrad /5-/6-/7 production summaries; Honda SOHC homologation paperwork for the K0-K8 line. Third, marque-historian references stand on the primary record rather than replacing it — Mick Walker's books on the Triumph twins, Rainer Vetter on the BMW /7 wiring evolution, Jerry Hatfield on the Indian 1927-1940 Scout line — cited where they fill a gap the factory record did not cover. Fourth, owner-club archives: AMOC (Antique Motorcycle Club), INOA (Indian National Owners Association), the Vintage Japanese Motorcycle Club, and the marque-specific clubs whose members have ridden the years we are writing about. Where two sources disagree, both numbers are quoted inline with the conflict flagged. This section is the most-edited part of every guide — release notes for each revision list the sources added, corrected, or replaced.

Will this actually fit how you restore?