AvK Posted July 9, 2021 Report Share Posted July 9, 2021 (edited) 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, 2021 by AvK Quote Link to comment Share on other sites More sharing options...
Glayne Posted July 9, 2021 Report Share Posted July 9, 2021 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? Quote Link to comment Share on other sites More sharing options...
AvK Posted July 9, 2021 Author Report Share Posted July 9, 2021 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.. 🙂 Quote Link to comment Share on other sites More sharing options...
delberto Posted July 9, 2021 Report Share Posted July 9, 2021 i think he means hold throttle full open when kicking engine over to let max air in to cylinder. 1 Quote Link to comment Share on other sites More sharing options...
mbeers6 Posted July 9, 2021 Report Share Posted July 9, 2021 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. 1 Quote Link to comment Share on other sites More sharing options...
AvK Posted July 9, 2021 Author Report Share Posted July 9, 2021 Thanks... I will try. Quote Link to comment Share on other sites More sharing options...
Glayne Posted July 10, 2021 Report Share Posted July 10, 2021 Any new results? I would go test mine for comparison, but apparently I would have to shut it off🤪 Quote Link to comment Share on other sites More sharing options...
mcman56 Posted July 10, 2021 Report Share Posted July 10, 2021 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.. 1 Quote Link to comment Share on other sites More sharing options...
Glayne Posted July 10, 2021 Report Share Posted July 10, 2021 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?) Quote Link to comment Share on other sites More sharing options...
Glayne Posted July 10, 2021 Report Share Posted July 10, 2021 (edited) 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, 2021 by Glayne Spelling Quote Link to comment Share on other sites More sharing options...
AvK Posted July 13, 2021 Author Report Share Posted July 13, 2021 I have ordered a new oversized piston, size C. Will take a while to arrive. so... to be continued. thanks for your support.. Quote Link to comment Share on other sites More sharing options...
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