Valves
This was on a 1989 R100GS with 52,000 miles. Pulse air system in place. You can see the face of the valve beginning to crack; here are two better pictures of the valve itself. Click for close-ups.
Valve sizes
| Engine | 27 | 29 | 31 | 32 | 34 | 36 | 38 | 40 | 42 | 44 | Guide |
|---|---|---|---|---|---|---|---|---|---|---|---|
| R50/5 | EX | IN | 8 | ||||||||
| R69S, R60 | EX | IN | |||||||||
| R75, R80 | EX | IN | |||||||||
| R90, R100 32mm* | EX | IN | |||||||||
| R100 40mm** | EX | IN | |||||||||
| R100 '88-on | EX30° | IN | |||||||||
| R50, 60/2 | EX | IN | 7 | ||||||||
| R65 early | EX | IN | |||||||||
| R65 late | EX | IN | |||||||||
| R1100 to 10/95 | EX30° | IN | 6 | ||||||||
| R850 | EX | IN | 5 | ||||||||
| R11xx 10/95-on | EX | IN | |||||||||
| R1200 | EX | IN |
* '77-84 R100 models with 32mm carbs
** '77~84 R100 models with 40mm carbs
