- Camshaft lobes
Blue discoloration/pitting/scratches → Replace the camshaft.
2. Measure:
- Camshaft lobe dimensions "a" and "b"
Out of specification → Replace the camshaft.
Camshaft lobe dimension limit Intake A 37.350-37.450 mm (1.4705-I.4744 in).
Limit 37.250 mm (1.4665 in).
Intake B 28.034-28.134 mm (1.10371.1076 in).
Limit 27.934 mm (1.0998 in).
Exhaust A 36.450-36.550 mm (1.43501.4390 in).
Limit 36.350 mm (1.4311 in).
Exhaust B 28.006-28.106 mm (1.10261.1065 in).
Limit 27.906 mm (1.0987 in).
![](https://motoinstruction.ru/img/yamaha/20/126610.jpg)
3. Measure:
- Camshaft runout
Out of specification → Replace.
Camshaft runout limit 0.030 mm (0.0012 in).
![](https://motoinstruction.ru/img/yamaha/20/126611.jpg)
4. Measure:
- Camshaft-journal-to-camshaft-cap clearance
Out of specification → Measure the camshaft journal diameter.
Camshaft-journal-to-camshaft-cap clearance 0.028-0.062 mm (0.0011-0.0024 in).
a. Install the camshaft into the cylinder head (without the dowel pins and camshaft caps).
b. Position strip of Plastigauge "1" onto the camshaft journal as shown.
![](https://motoinstruction.ru/img/yamaha/20/126612.jpg)
c. Install the dowel pins and camshaft caps.
- Tighten the camshaft cap bolts in stages and in a crisscross pattern, working from the inner caps out.
- Do not turn the camshaft when measuring the camshaft journal-to-camshaft cap clearance with the Plastigauge.
Camshaft cap bolt 10 Nm (1.0 m·kgf, 7.2 ft·lbf).
d. Remove the camshaft caps and then measure the width of the Plastigauge "2".
![](https://motoinstruction.ru/img/yamaha/20/126613.jpg)
5. Measure:
- Camshaft journal diameter "a"
Out of specification → Replace the camshaft.
Within specification → Replace the cylinder head and the camshaft caps as a set.
Camshaft journal diameter 25.459-25.472 mm (1.0023-1.0028 in).
![](https://motoinstruction.ru/img/yamaha/20/126614.jpg)