Connecting Rod Checking

Also called "Con Rod" by some people.. Its a very important thing for every 2 stroke and 4 stoke engine.. Connecting rod is used to joint the crank and piston.. Even the name is "Rod", the part is not in a tubular or cylinder shape..

This part usually give a problem to 2 stroke user especially RXZ.. In a high speed riding, the engine would produce a heat especially on whole of the ball bearing... Dis-advantage on 2 stroke engine is the bearing on the crank shaft, connecting rod and piston is not lubricated by any liquid even oil or water.. So, the bearing have a high percentage to overheat and burnt.. In a high speed with a high temperature, the connecting rod would meet the "melt temperature" and the material is become soft.. At this moment, if the bearing jammed, the system would automatically stop... By having a momentum from the movement of bike, clutch and gear, it would damage the connecting rod..

Beside that, without a balance setting for 2T oil, the resistance on the piston to block would be increase.. In the same time, heat which produced would cause the piston to effloresce.. In a time when the piston become to over size than the limit, it would be jammed and stuck in the block... Momentum inertia from the engine gears movement would cause the connecting rod system to damage..


If it happen, we have to fully overhaul the engine and change the connecting rod system which include the bearing, washer and pin crank... Sometimes, the engine would unable to start once jammed.. This is because of loss compress from the piston.. By changing the piston, it would able to start back but the side effect is too much.. Firstly, the engine would produce a knocking sound from the crank pin, bearing and connecting rod... Second, the engine would not smooth and the engine knocking sound become louder... Finally, the faulty would affect the piston and ring.. If u unlucky, your engine would difficult to start on the next day and the ring sound would be appear...

To check the connecting rod condition, firstly pull and push the rod at "A" direction.. In the same time, hold the crank.. There MUST BE no free play at this direction.. Next, move on "B" direction.. It would have a little free play but not too much.. The vector is about 2-3mm only.. More than that would consider as worn..

Connecting rod system is included:

4. connecting rod

5. crank pin

6. washer (2x)

7. bearing

Current price (on Nov 2010) for RXZ connecting rod system is around RM160.. This price is not include assembly cost which around RM30.. Take note that we unable to dismantle and assemble the connecting rod system into crank ourself without a proper and special tools.. Make sure that use the original parts from Yamaha... Do not use a cheaper or called Japan product.. Original connecting rod would have emblem "55K" instead of " Made in Japan"... Reminder, this part is very important to care..