Compression stroke???

3 replies to this topic
  • azmanxman

Posted June 29, 2007 - 08:39 PM


So I'm OK with the valve adjustment process other than one issue. Is there some idiot-proof way of being sure which "stroke" I'm on while rotating the flywheel?

I've read several valve-adjustment post and I'm ready to have a go, but I'm just not completely sure about this step.

I know to look for "slight free play in the left intake and exhaust rocker arms", but is there anything else I should be looking for just to be sure??


  • Billahjack

Posted June 29, 2007 - 09:41 PM


A 4-stoke engine is at TDC for two different parts of the 4-stroke cycle.

TDC, End of Compression stroke, start of combustion stroke - All valves are closed as you approach and pass the "T" mark on the flywheel.

TDC, End of exhaust stroke, beginning of Intake stroke - Exhaust Valves are closing as you approach the "T" and intake valves are opening.

Basically, watch the valves as you rotate the crank.

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  • creeky

Posted June 30, 2007 - 06:01 AM


Watch the intake rockers as you rotate the engine. When the intakes close, the piston is coming up on compression stroke. Line up the "T" mark, you are ready to adjust.

  • chuck2000

Posted June 30, 2007 - 02:40 PM


There is a nice graphic on valve opening/closing here:

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