pid = threads.php

Common thread and fastener sizes found on motorcycles.

American AF /SAE
spanner jaw (in)	bolt diam (in)	threads per inch		bolt diam (mm)
		UNF	UNC


7/16	1/4	28	20	6.35
1/2	5/16	24	18	7.93
9/16	3/8	24	16	9.53

11/16	7/16	20	14	11.11
3/4	1/2	20	13	12.70
7/8	9/16	18	12	14.28
15/16	5/8	18	11	11.00

Metric ISO
spanner jaw (mm)	bolt diam (mm)	pitch (mm)		tpi
		Fine	Coarse	F	C
10	6	0.75	1.00	33.86	25.4
11	7	---	1.00	---	25.4

13	8	1.00	1.25	25.4	20.32


17	10	1.00* 1.25	1.50	25.4 20.32	16.93
19	12	1.25*	1.75	20.32	14.51
22	14	1.50 1.25*	2.00	16.93	12.70
24	16	---	2.00	----	12.70
27	18	*1.50	2.50	16.93	10.16
* spark plug threads

Cycle
bolt diam (in)	tpi/p>
1/4	26
5/16	26
3/8	26
7/16	26
1/2	26
9/16	26 or 20
5/8	26 or 20

Cycle
bolt diam (in)	tpi
1/8	40
1/4	26
5/16	26
3/8	26
7/16	26
1/2	26
9/16	26 or 20
5/8	26 or 20
11/16
3/4	26 or 20
7/8	24 or 20
1	24

BSF
bolt diam (in)	tpi

1/4	26
5/16	22
3/8	20
7/16	18
1/2	16
9/16	16
5/8	24
11/16	14
3/4	12
7/8	11
1	10

BSW
bolt diam (in)	tpi
1/8	40
1/4	20
5/16	18
3/8	16
7/16	14
1/2	12
9/16	12
5/8	11
11/16	11
3/4	10

BSP
tube bore (in)	tpi
1/8	28
1/4	19

3/8	19

1/2	14

BA
size no.	pitch (mm)
0	1.00
1	0.90
2	0.81
3	0.73
4	0.66

For further information: e-mail to: webmaster Last updated: 25 April 2008