July 9, 20215 yr Hey, Does anyone have experience with a compression test? I understand there is no standard. It will be different per engine, but I am looking for an indication whether the piston/cylinder may be worn. I now measure 75PSI and according to an earlier topic that is too little. who can help give me some advice? The bike is an Gasgas TXT300. 🙂 Best regards.. Alex Edited July 9, 20215 yr by AvK
July 9, 20215 yr Possibly a dumb question, was this done at full throttle? it should be. Can you pull the header pipe and check for any piston wear around the exhaust outlet?
July 9, 20215 yr Author 7 minutes ago, Glayne said: Possibly a dumb question, was this done at full throttle? it should be. Can you pull the header pipe and check for any piston wear around the exhaust outlet? Its not a dumb question but a compresion test you do not do at full throttle bub when the motor is not running. Like the picure.. 🙂
July 9, 20215 yr i think he means hold throttle full open when kicking engine over to let max air in to cylinder.
July 9, 20215 yr Yes you need to do test with throttle wide open (engine of course off). My '17 with 375 hours tested at 145psi so I'd say try again with throttle WFO. If still that low, then you have issues.
July 10, 20215 yr Any new results? I would go test mine for comparison, but apparently I would have to shut it off🤪
July 10, 20215 yr I have tested several trials bikes and have always gotten something around 155 psi, maybe +/- 5. It would be good if you had some way to check the accuracy of your gauge...or test another bike for comparison because the gauge could be off..
July 10, 20215 yr 1 hour ago, mcman56 said: I have tested several trials bikes and have always gotten something around 155 psi, maybe +/- 5. It would be good if you had some way to check the accuracy of your gauge...or test another bike for comparison because the gauge could be off.. I totally agree, seems many gauges can vary in accuracy. (especially mine?)
July 10, 20215 yr Well, curiosity got to me. Was doing milkshake maintenance anyways. 5 safety flipflop kicks! 2012 280 with I think fairly low hours for it's age. Edited July 10, 20215 yr by Glayne Spelling
July 13, 20215 yr Author I have ordered a new oversized piston, size C. Will take a while to arrive. so... to be continued. thanks for your support..
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