CONCORD, NC - Please note the following clarifications and/or changes to the 2016 Technical Manual: Blowdown checking procedure for Yamaha engines --- (601.9 and Figure 606.2)
1 -- By a careful visual inspection (light check) , identify the highest exhaust port and the highest intake port.
2 -- Using the Lad tool, zero the dial indicator on the highest exhaust port, taking care to hold the shaft of the tool against the cylinder wall.
3 -- roll the crankshaft backwards five turns (.500" on the dial indicator)
4 -- insert the Lad tool into the highest intake port, holding the shaft of the tool against the cylinder wall.
5 -- roll the crankshaft forward until the piston stops on the Lad tool and note the value.
6 -- the value must be between .380" and .420" to be considered legal
7 -- engine to be checked as raced