Part 26 Re-Fitting The Pistons ...

Introduction ...

This page contains photos of the process of refitting the pistons to a ROTAX 912ULS engine (built August 2006).



ROTAX 912ULS refitting the pistons

Image 1

Start by ensuring that you have the correct piston for the cylinder you are working on. The piston pin is displayed here "started" in the piston. Here we have a piston ring compression tool and a fresh monoclip circlip at the ready. We make a start on cylinder 1 ...

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ROTAX 912ULS refitting the pistons

Image 3

The conrod is orientated to TDC. The upper 2 cylinder studs are removed temporarily to facilitate access ...

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ROTAX 912ULS refitting the pistons

Image 4

To protect the pistons rings an uncontaminated rag is placed on the lower two cylinder studs to prevent any damage to the face of the piston rings ...

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ROTAX 912ULS refitting the pistons

Image 6

The piston is offered up to the conrod and the piston pin is pushed through the smallend of the conrod having greased the piston pin, the smallend and the piston pin channel. Be careful during this process not to exert any lateral force on the conrod (which might stress the big end bearings) taking care to support the conrod and the piston throughout the process ...

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ROTAX 912ULS refitting the pistons

Image 7

Here the piston pin can be seen fully inserted home ready to accept a monohook circlip ...

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ROTAX 912ULS refitting the pistons

Image 9

Place the new monohook circlip into the Rotax circlip insertion tool and place the shaft of the insertion tool throuth the centre of the piston pin until ...

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ROTAX 912ULS refitting the pistons

Image 10

The end of the insertion tool locates fully in the circlip channel ...

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ROTAX 912ULS refitting the pistons

Image 11

Rotate the circlip insertion tool until the "hook" or curved section of the monohook is orientated correctly so that when we tap the insertion tool the monohook will correctly locate in the circlip channel in the piston. With a firm tap on end of the inserton tool the circlip should be transferred to the circlip channel and locate correctly. Before you tap the insertion tool it is important to apply a small amount of positive pressure to the insertion tool to ensure is stays located and orientated correctly emmediately prior to tapping the circlip in. Failure to do this usually results in the circlip popping out of the insertion tool without being transfered to the circlip groove in the piston and you will have to start over again. Once you have successfully used the insertion tool to transfer the circlip to the circlip groove in the piston visually inspect the circlip to ensure that it is seated in the circlip groove all the way around it's circumference and that it has "relaxed" into the circlip groove fully ...

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ROTAX 912ULS refitting the pistons

Image 12

The piston fitted to the conrod ...

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