Shop Grant cast-iron piston ring sets and complete piston-and-ring sets for classic Triumph 500, 650 and 750 twins, Norton Commando 750 and 850, and BSA A65 650 twins. Grant has made piston rings since 1922. Each ring set holds four compression rings and two oil control rings, enough for one twin-cylinder engine, in standard size and oversizes to +.060″. We offer free shipping to the lower 48 states.
BSA A65 650 Lightning Thunderbolt etc Pistons (2) with Grant Piston Rings Set 1962-72 PN# 68-0784 68-0299 US 68-0256 US
$110.21 – $130.08Price range: $110.21 through $130.08
Triumph 500 T100 Late 69mm Piston Set Complete w/Grant Piston Rings 1967-74 PN# 70-6884 E6884 70-6893 70-6894 US
$101.09 – $133.44Price range: $101.09 through $133.44
Triumph 500 5TA T100 Early 69mm Piston Set Complete w/Grant Piston Rings 1958-66 PN# CP179 70-4021 E4021 70-6893 US
$186.74 – $212.33Price range: $186.74 through $212.33
Triumph 750 TR7 T140 76mm Piston Set Complete w/Grant Piston Rings PN# 71-3676 71-3690 71-3695 US
$116.78 – $137.23Price range: $116.78 through $137.23
Triumph 650 TR6 T120 71mm Piston Set Complete w/Grant Piston Rings PN# 70-9488 E9488 70-6864 US
$116.50 – $136.10Price range: $116.50 through $136.10
Norton 850 Commando 77mm Piston Set Complete w/Grant Piston Rings PN# 06-3838 06-7958 US
$116.61 – $133.45Price range: $116.61 through $133.45
Norton 750 Commando Pistons with Grant Rings PN# 06-0381 06-0952 US
$118.68 – $145.73Price range: $118.68 through $145.73
BSA A65 650 Lightning Thunderbolt Grant Piston Ring Set 1962-72 PN# 68-0299 US 68-0256 US
$34.33 – $49.55Price range: $34.33 through $49.55
Norton 850 Commando Grant Piston Ring Set 1973-75 PN# 06-7958 US
$37.41 – $38.19Price range: $37.41 through $38.19
Norton Commando 750 Grant Piston Ring Set PN# 06-0952 US 06-0953 06-0954
$37.43 – $65.37Price range: $37.43 through $65.37
Triumph 750 Bonneville Tiger T140 TR7 Grant Piston Ring Set USA Made PN# 71-3690 US 71-3695 US
$26.56 – $43.36Price range: $26.56 through $43.36
Triumph 650 Bonneville Tiger T120 TR6 Grant Piston Ring Set USA Made PN# 70-6864 US 70-6865
$33.35 – $41.20Price range: $33.35 through $41.20
Triumph 500 T100 Grant Piston Ring Set USA Made PN# 70-6893 US 70-6894
$24.80 – $49.16Price range: $24.80 through $49.16
Table of Contents
Grant Piston Rings: Making Rings Since 1922
Gerald “Gerry” Grant founded Grant in 1922, in the era of the Ford Model T. Early engines didn’t last long, so he first sold engine rebuild kits and then moved into making piston rings (Grant Piston Rings). Much of the company’s early reputation came from supporting the California race car and hot rod scene (Grant Piston Rings).
Grant was involved in hill climbs, streamliners and the Indianapolis 500. In 1952 the company sponsored a specially built Ferrari for the 1952 Indianapolis 500, driven by Johnnie Parsons, but ignition trouble kept it from qualifying. When Gerry Grant died in 1952, the business passed to his nephews, Grant and Dick MacCoon. In 1955 Grant took over the 200 Mile Per Hour Club and helped pioneer high-speed runs at the Bonneville Salt Flats in Utah (Grant Piston Rings).
Grant Piston Rings is based in Anaheim, California (Grant Piston Rings). Today it supplies ring sets for passenger cars, light trucks, industrial engines, air brake compressors and motorcycles, mainly for the aftermarket (Grant Piston Rings). Browse the full range in Grant’s catalogs.
What Piston Rings Do
Piston rings seal the gap between the combustion chamber and the crankcase. During the compression and power strokes, the compression rings seal in the combustion gases and limit blow-by. The oil ring wipes excess oil off the cylinder wall and leaves a thin film to lubricate the rings. As rings wear, they let more oil into the combustion chamber and more gas past the piston, and that’s when it’s time for a new set (Grant Piston Rings; Wikipedia: Piston ring).
Grant’s plain cast-iron sets use high-grade grey iron castings, and the top compression ring is black phosphate coated. Grant also makes chrome, plasma-moly and steel ring sets for other applications (Grant Piston Rings). The ring sets we stock for British twins are cast iron.
Grant Piston Ring Sets for Triumph Twins
Each set has four compression rings and two oil control rings, enough for both cylinders:
- Triumph 500 T100, T100C, T100R and TR5 unit twins up to 1974 (70-6893 / 70-6894): standard, +.020, +.040, +.060 and +.080
- Triumph 650 T120 Bonneville, TR6 Tiger and Trophy up to 1972 (70-6864 / 70-6865): standard, +.020, +.040 and +.060
- Triumph 750 T140 Bonneville and TR7 Tiger from 1973 (71-3690 / 71-3695): standard, +.020, +.040 and +.060
Background on these models: Triumph Tiger 100 and Triumph Bonneville on Wikipedia. See more Triumph engine parts and Triumph gaskets.
Grant Piston Ring Sets for Norton Commando
- Norton Commando 750, 73mm bore (06-0952 / 06-0953 / 06-0954): standard, +.020, +.040 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 are made for pistons with an oil ring groove about .180″ deep, and are not recommended for original pre-1972 pistons with shallower grooves.
- Norton Commando 850, 1973–75 (06-7958): standard, +.020, +.040 and +.060
The Commando 750 has a 73mm bore and the 850 a 77mm bore (Wikipedia). See more Norton engine parts and Norton gaskets.
Grant Piston Ring Sets for BSA A65
- BSA A65 650 Lightning, Thunderbolt and other A65 models, 1962–72 (68-0299 / 68-0256): standard, +.020, +.040 and +.060
The A65 is BSA’s unit-construction 650 twin, built from 1962 (Wikipedia). See more BSA engine parts and BSA gaskets.
Complete Piston Sets with Grant Rings
These sets pair two pistons, with wrist pins and circlips, with a full Grant ring set. Most use cast JCC reproduction pistons marketed by Emgo:
| Set | Bore | Notes |
| Triumph 500 5TA and T100, early, 1958–66 | 69mm | 9:1 pistons for “squish-band” cylinder heads; not for 1967 and later 500s |
| Triumph 500 T100, late, 1967–74 | 69mm | 9:1 pistons for heads with 1-17/32″ inlet valves; not for squish-band heads |
| Triumph 650 T120 and TR6 | 71mm | 9:1 pistons |
| Triumph 750 T140 and TR7 | 76mm | 8.5:1 pistons; not for early 724cc engines with 75mm pistons |
| Triumph 650 to 750 Aerco big bore replacement | 76mm | Aerco pistons for Aerco PS215 long-rod big-bore barrels; standard bore only; not for T140 or TR7 cylinders |
| Norton 750 Commando | 73mm | Pistons with Grant 750 rings |
| Norton 850 Commando | 77mm | JCC/Emgo pistons |
| BSA A65 650, 1962–72 | 75mm | Lightning, Thunderbolt and other A65s |
Bore sizes and notes come from each product listing. Oversize pistons are available to +.060″ on most sets.
How to Choose and Fit Grant Piston Rings
- Measure your bores. Have your cylinders measured to find the current size, then choose standard or the matching oversize (+.020, +.040, +.060 and, for the T100, +.080).
- Match rings to pistons. If you keep your pistons, check the ring grooves. The Norton 750 Grant rings, for example, need an oil ring groove about .180″ deep.
- Fit pistons to the barrels when reboring. A machine shop should measure the actual pistons, then bore and hone the cylinders to the specified clearance. Cast-iron rings need a proper cross-hatch hone to seat (Wikipedia: Honing).
- Check ring end gaps in the bore before fitting the rings to the pistons. Fit compression rings with the “top” marking facing up.
- Renew the top-end gaskets and follow the factory workshop manual. Shop Triumph manuals, Norton manuals and BSA manuals, plus 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. For other ring and piston options, see Hepolite. Need help? Contact our team.
Shop Grant Piston Rings
Browse the Grant 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).
Grant Piston Rings FAQ
Who makes Grant piston rings?
Grant Piston Rings was founded by Gerry Grant in 1922 and is based in Anaheim, California. It makes ring sets for cars, trucks, industrial engines, air brake compressors and motorcycles (Grant Piston Rings).
Which motorcycles do your Grant piston rings fit?
We stock Grant ring sets for the Triumph 500 T100 and TR5 up to 1974, the Triumph 650 T120 and TR6 up to 1972, the Triumph 750 T140 and TR7 from 1973, the Norton Commando 750 and 850, and the BSA A65 650 from 1962 to 1972.
Does one Grant ring set do both cylinders?
Yes. Each set has four compression rings and two oil control rings, which is enough for one twin-cylinder engine.
What oversizes are available?
Most Grant sets come in standard, +.020, +.040 and +.060. The Triumph 500 T100 set is also available in +.080.
Will Grant rings fit my original Norton Commando 750 pistons?
Not always. The Grant 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.
Do the piston sets include wrist pins and circlips?
Yes. Each piston set includes two pistons, wrist pins, circlips and a full Grant 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 with 1-17/32″ inlet valves. Don’t mix them.
Do I need to check piston ring end gap?
Yes. Check each ring’s end gap in its cylinder before fitting the rings to the pistons, and set it to the workshop manual specification. Fit compression rings with the “top” mark facing up.
Do I need to hone the cylinders?
Yes, if the bores are being reused or rebored. Cast-iron rings need a proper cross-hatch hone pattern to seat and seal.
Do you offer free shipping on Grant piston rings?
Yes. Orders ship free to the lower 48 US states with no minimum order. Weekday orders placed before noon Mountain Time ship the same day.
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