Squish Area - BOMBARDIER 1996 Ski-doo MX Z440 Handbook

6. Exhaust system restrictions.
a. Muffler plugged/ restricted
b. Tailpipe diameter too small
c. Incorrect design of expansion
7. General overheating
a. Broken fan belt
b. Loss of coolant
c. Lack of snow on heat exchangers
8. Coolant or water entering combustion chamber
Rotax cylinder heads incorporate a squish area. This area is basically a "ledge" projecting beyond
the combustion chamber area. in operation, as the piston ascends and approaches the ledge, a
rapid squeezing action is applied to the air/fuel mixture contained in the area immediately
between the piston dome and the ledge.
rapidly into the combustion chamber area, creating a greater mixture turbulence. Additionally, the
small volume and large surface area of the squish band allow a better cooling of
help prevent detonation.
, F01D5WS
1. Squish area 1.27-1.78 (.050 -.070 in)
If the squish clearance is increased, a loss in power will occur while too small a squish clearance
will lead to detonation.
The squish clearance can be measured by inserting a piece of rosin core solder into the combustion
chamber, rotating the engine through T. D. C., removing the solder and measuring the thickness of
the compressed solder.
Section 04
chamber
This squashing action forces the entrapped mixture
ENGINE PREPARATION
the end gases to
04-17