PIS­TONS

Motorcycle News (UK) - - Garage -

Pis­tons or­ches­trate the suck, squeeze bang, blow mantra we are all fa­mil­iar with. More specif­i­cally, the pis­ton trans­fers the en­ergy from the ex­pand­ing gasses of com­bus­tion to the crank­shaft, via the con­nect­ing rod. To do this ef­fi­ciently it must op­ti­mise the pres­sure by seal­ing the com­bus­tion cham­ber – with as­sis­tance from the pis­ton rings – against gas leak­age into the crank­case and pre­vent lu­bri­cat­ing oil get­ting into the com­bus­tion cham­ber. On top of that it must ab­sorb heat from the com­bus­tion process and dis­si­pate it into the cylin­der wall.

With com­bus­tion tem­per­a­tures in ex­cess of 2000°C the top of the pis­ton will typ­i­cally run at around 300°C. The pis­ton may be sub­jected to pres­sures as high as 3000 pounds per square inch and huge forces of in­er­tia caused by the ex­tremely rapid ac­cel­er­a­tion (pos­i­tive and neg­a­tive). The pis­ton stops at the top and bot­tom of each stroke to re­verse di­rec­tion and reaches peak ve­loc­i­ties of around 40 me­tres per sec­ond in be­tween. In 10,000 miles a typ­i­cal su­per­bike’s en­gine’s pis­tons will have trav­elled around 14,000 miles and re­versed di­rec­tion one hun­dred and fifty mil­lion times.

The very em­bod­i­ment of in­ter­nal com­bus­tion and the hard­est work­ing com­po­nent in your en­gine

He’s had 30 years of ex­pe­ri­ence build­ing, mod­i­fy­ing and re­pair­ing bikes from su­per­monos to CBX1000 café rac­ers.

In 10,000 miles your pis­ton will have been up and down 150,000,000 times

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