| A
SHORTER PIPE LENGTH WILL RAISE THE R.P.M. or more
exactly it will raise the RPM point where maximum
power is produced.
A LONGER PIPE LENGTH WILL LOWER THE
R.P.M. or more exactly it will lower the RPM point
where maximum power is produced
Adjustment
1. Fix the manifold and pipe in position at the length
shown on the chart above, making sure that there are
no steps or leaks in the manifold to engine joint.
2. Run the boat on the normal propeller and set the
needle valve for the best straight-line performance.
3. Turn the boat in 90-degree turns. If the motor
loads or slows considerably then the pipe length is
too short or the propeller is too big. If the motor
slows a little or not at all then shorten the manifold
slightly or try the next size up propeller
4. Shorten or lengthen the manifold until the best
balance in performance is obtained between turns and
straight-line speed. |
| Engine |
Size |
Length
R.P.M |
| 3.5cc(.21) |
21
to 24 cms |
23,000
to 27,000 |
| 3.5cc
geared |
18.5
to 20 cms |
30,000
to 33,000 |
| 6.5cc/7.5cc(.40/.50) |
26
to 30 cms |
18,000
to 22,000 |
| 6.5cc/7.5cc
geared |
22
to 25 cms |
24,000
to 29,000 |
| 11cc(.67) |
29
to 32 cms |
19,000
to 22,000 |
| 13cc(.80) |
29
to 32 cms |
19,000
to 22,000 |
| 15cc(.90) |
31
to 34 cms |
19,000
to 22,000 |
| 22cc/25cc |
38
to 42 cms |
12,000
to 15,000 |
|
