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AvK

compression test

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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 by AvK

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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?

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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.. 🙂 

IMG_0974.JPG

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i think he means hold throttle full open when kicking engine over to let max air in to cylinder.

 

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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. 

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Thanks... I will try. 

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Any new results? I would go test mine for comparison, but apparently I would have to shut it off🤪

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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..  

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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?)

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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.

20210710_153733.jpg

Edited by Glayne
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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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