Motorcycle Compression Tester

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The Actron CP7828 is the compression tester I have in my toolbox. It comes with everything you need, including multiple adapters for all types of motorcycles (10mm, 12mm, 14mm, 14mm long reach, and 18mm standard spark plug thread). Also, it comes with extra o-rings and valves in case they are damaged during use. I initially bought the Actron CP7827 shown below on the right, except it did not come with the 10 & 12mm adapters. Spend the extra few bucks and purchase the one shown on the left.


Motorcycle compression gauge tester Acton CP7828


I bought mine from Amazon about 3 years ago and use this tool all the time. One thing you don’t want to do is guess on how much compression your bike has. I was working on a bike which I thought had great compression just by kicking it over, in reality when tested, it was well below what the service manual states. So get a gauge!

Once you have this tool, check out my post on how to perform a compression test.



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  • Ruben Banuelos

    My 81 Honda cb650 has had some carb issues, the choke spring is giving me some issues and I was wondering if you can post a video tutorial on removal, instillation, and replacement?

    • Matthew


      Next time I encounter your issue, I will make a vid on the repair.

  • Dennis

    This is only for 2-Stroke? or 4-Stroke motorcycle not dirtbikes?

    If its for 4-stroke dirtbikes:
    How do you use it? and how do you “stop” auto-decompression like the CRF250 have (probably other models have it to)?

    • Matthew

      Engines with auto decompression will give lower results. The service manual may or may not give a value for this.

      For thumpers with auto decomp, I skip comp test and go right to leak down testing. Even leak down is difficult since the air pressure rotates the motor or the tester will not fit down the plug well.

      I haven’t tried to deactivate the auto decomp, and don’t need a sprained ankle either 🙂