Shop Hastings piston ring sets and complete piston-and-ring sets for classic Triumph 500 and 750 twins, the Norton Commando 750 and 850, and BSA A65 650 twins. Hastings Manufacturing of Hastings, Michigan, has made piston rings since 1923 and invented the Flex-Vent oil ring. Each ring set covers both cylinders of a twin. Every listing shows the original part numbers and available sizes. We offer free shipping to the lower 48 states.
BSA A65 650 Lightning Thunderbolt etc Pistons (2) with Hastings Piston Rings Set 1962-72 PN# 68-0784 68-0299 H 68-0256 H
$138.11 – $174.81Price range: $138.11 through $174.81
BSA A65 650 Lightning Thunderbolt Hastings Piston Ring Set 1962-72 PN# 68-0299 H 68-0256 H
$64.02 – $95.74Price range: $64.02 through $95.74
Triumph T140 TR7 750 Hastings Piston Ring Set PN# 71-3690 H 71-3695 H
$69.82 – $95.74Price range: $69.82 through $95.74
Norton Commando 750 Hastings Piston Ring Set PN# 06-0952 06-0953 06-0954 H
$68.25 – $86.64Price range: $68.25 through $86.64
Norton 750 Commando Pistons with Hastings Rings PN# 06-0381 06-0952 H
$147.82 – $166.30Price range: $147.82 through $166.30
Triumph TR7 140 750 Bonneville Tiger Pistons with Hastings Rings PN# 71-3676 71-3690 H 71-3695
$161.45 – $183.12Price range: $161.45 through $183.12
Table of Contents
Hastings Piston Rings: Over a Century in Hastings, Michigan
Aben Johnson founded Hastings Manufacturing in Hastings, Michigan, in 1915 to make aftermarket car accessories. The company introduced its first cast-iron piston rings in 1923 (Reference for Business).
When Ford made its high-compression flathead V8 standard in 1932, one-piece cast-iron oil rings struggled to control oil. Hastings answered in 1935 with the “Steel-Vent,” the first multiple-piece oil control ring, and advertised it with its cartoon “Tough Guy” (Reference for Business). In 1956 Hastings introduced the three-piece Flex-Vent oil ring (Reference for Business). Hastings calls its Flex-Vent expander “the design standard by which all other oil rings are compared today” (Hastings Piston Rings).
Hastings later added the Mini Flex-Vent and Hyper-Vent oil rings. In 1998 it became the first piston ring maker to earn the TS-16949 quality standard (Hastings brochure). In 2017 it merged with the Czech ring maker Piston Rings Komárov. In April 2026, Japan’s NPR-Riken Corporation bought Hastings (Stout). The company still operates at 325 N. Hanover Street in Hastings, Michigan (Hastings Piston Rings), and its range covers cars, trucks, farm and industrial engines, and motorcycles (LinkedIn: Hastings Manufacturing).
How a Piston Ring Set Works
A Hastings set has three kinds of ring (Hastings Piston Rings):
- Top compression ring: seals combustion gases above the piston and moves heat from the piston to the cylinder wall.
- Second compression ring: also called the oil scraper ring. It wipes oil down the bore and adds a second gas seal.
- Oil control ring: leaves a thin oil film on the cylinder wall and returns the excess to the crankcase.
When rings wear, the engine burns more oil, loses compression and pushes more gas into the crankcase, known as blow-by. See Wikipedia: Piston ring for more background.
Hastings Piston Ring Sets for Triumph Twins
Each set is enough for both cylinders of a twin:
- Triumph 500 T100, 1958–74 (70-6893 / 70-6894): standard bore, for T100 500cc twins
- Triumph 750 T140 Bonneville and TR7 Tiger, 1972–82 (71-3690 / 71-3695): +.020, +.040 and +.060 oversizes
Background on these models: Triumph Tiger 100 and Triumph Bonneville on Wikipedia. See more Triumph engine parts and Triumph gaskets.
Hastings Piston Ring Sets for Norton Commando
- Norton Commando 750, 73mm bore (06-0952 / 06-0953 / 06-0954): standard and +.060. The top ring has a PVD chromium-nitride face, the second ring is black phosphate coated, and the oil ring is a two-piece design with an expander spring. These rings fit pistons with an oil ring groove about .180″ deep. They are not recommended for original pre-1972 pistons, which have shallower grooves.
- Norton Commando 850, 1973–75 (06-7958): Hastings ring set for the 77mm bore
The Commando 750 has a 73mm bore and the 850 a 77mm bore (Wikipedia: Norton Commando). Andover Norton, which holds the original Norton drawings, lists 06.7958 as the standard 850 ring set (Andover Norton). See more Norton engine parts and Norton gaskets.
Hastings Piston Ring Sets for BSA A65
- BSA A65 650 Lightning, Thunderbolt and other A65 models, 1962–72 (68-0299 / 68-0256): Hastings ring set for the 75mm bore
The A65 is BSA’s unit-construction 650 twin, built from 1962 (Wikipedia: BSA A65). See more BSA engine parts and BSA gaskets.
Complete Piston Sets with Hastings Rings
These sets combine two pistons, wrist pins and circlips with a full Hastings ring set. Several use cast reproduction pistons from EMGO:
| Set | Bore | Pistons |
|---|---|---|
| Triumph 500 5TA and T100, early, 1958–66 | 69mm | CP179 / 70-4021; for the earlier “squish-band” cylinder heads |
| Triumph 500 T100, T100C and T100R, late, 1967–74 | 69mm | 70-6884; for the later cylinder heads |
| Triumph 750 T140 and TR7 | 76mm | 71-3676; not for early 724cc engines with 75mm pistons |
| Norton 750 Commando | 73mm | 06-0381 |
| Norton 850 Commando | 77mm | 06-3838 |
| BSA A65 650 Lightning, Thunderbolt and other A65s, 1962–72 | 75mm | Emgo 68-0784, in +.020, +.040 and +.060 |
Check each listing for the sizes in stock. If you only need pistons, see Triumph 750 pistons and Triumph 650 pistons, sold without rings.
How to Choose and Fit Hastings Piston Rings
- Measure your bores. Have a machine shop measure the cylinders, then pick standard or the matching oversize. Ring sets must match the bore size, not just the model.
- Match rings to pistons. If you keep your pistons, check the ring grooves. The Norton 750 rings, for example, need an oil ring groove about .180″ deep.
- Bore and hone to the actual pistons. When reboring, the machine shop should measure the new pistons and finish the bores with a cross-hatch hone so the rings can seat (Wikipedia: Honing).
- Check ring end gaps in the bore before fitting the rings to the pistons. Our Norton 750 listing suggests .004″ to .006″ per inch of bore for compression rings. Follow your workshop manual for your exact engine.
- Fit the oil ring carefully. On two-piece oil rings, set the expander spring gap 180 degrees from the ring gap. Rings are brittle, so a piston ring installation tool helps.
- Renew the top-end gaskets and follow the factory workshop manual. Shop Triumph manuals, Norton manuals, BSA manuals, Triumph parts books and workshop tools.
For more on top-end work, read our guides Triumph T100 Top End, Triumph Top End Sealing and What the Workshop Manual Doesn’t Explain, Eliminating Triumph Oil Leaks and Pattern Parts and Fettling to Perfection. Need help? Contact our team.
Compare Other Piston Ring Brands
We also stock Grant piston rings, made in Anaheim, California, and UK-made Hepolite rings and pistons for many of the same Triumph, Norton and BSA engines.
Shop Hastings Piston Rings
Browse the Hastings ring sets and piston sets above, or see all the brands we carry. Orders ship free to the lower 48 states, and weekday orders placed before noon Mountain Time ship the same day (Shipping and Returns).
Hastings Piston Rings FAQ
Who makes Hastings piston rings?
Hastings Manufacturing Company makes them in Hastings, Michigan. The company was founded in 1915 and made its first piston rings in 1923. Since April 2026 it has been owned by Japan’s NPR-Riken Corporation.
Which motorcycles do your Hastings piston rings fit?
We stock Hastings ring sets for the Triumph 500 T100 from 1958 to 1974, the Triumph 750 T140 and TR7 from 1972 to 1982, the Norton Commando 750 and 850, and the BSA A65 650 from 1962 to 1972. We also sell complete piston sets with Hastings rings for these engines.
Does one Hastings ring set do both cylinders?
Yes. Each ring set has enough rings for both cylinders of a twin-cylinder engine.
What sizes are available?
It depends on the set. The Triumph 500 T100 set is standard bore. The Triumph 750 set comes in +.020, +.040 and +.060, and the Norton 750 set in standard and +.060. Choose the size that matches your measured bores, and check each listing for current stock.
Will Hastings rings fit my original Norton Commando 750 pistons?
Not always. The Hastings 750 ring set is made for pistons with an oil ring groove about .180″ deep. It is not recommended for original pre-1972 Commando pistons, which have shallower oil ring grooves.
What is a Flex-Vent oil ring?
It is Hastings’ three-piece oil control ring, introduced in 1956. A Flex-Vent expander presses two thin steel rails evenly against the cylinder wall for consistent oil control.
Do the piston sets include wrist pins and circlips?
Yes. Each piston set includes two pistons, wrist pins, circlips and a full Hastings ring set.
Which Triumph 500 piston set do I need?
It depends on your cylinder head. The early 1958–66 set suits the “squish-band” heads, and the late 1967–74 set suits the later heads. Don’t mix them.
Do I need to check piston ring end gap?
Yes. Check each ring’s end gap in its own cylinder before fitting the rings to the pistons. As a guide, compression rings need about .004″ to .006″ per inch of bore, but follow your workshop manual.
Do you offer free shipping on Hastings piston rings?
Yes. Orders ship free to the lower 48 US states. Weekday orders placed before noon Mountain Time ship the same day.