Motorcycle Compression Tester
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.
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.
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?
Ruben,
Next time I encounter your issue, I will make a vid on the repair.
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)?
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 🙂
Hi Matthew please contact me when you have time. At the weekend I pushed the starter button on my BMR80GS (1981). I haven’t done the 3 checks yet. But the rapid machine gun clacking from the engine on trying to start is worrying me. Please tell the engine is not seized. A trickle charger (Optimate) is on during the week but I think the battery is flat. Thank you.
If all you here is clicking, then it sounds like not enough amperage. Check for loose connections and have battery tested.
good video and by the way i bought a compression tester to do my 1996 fireblade with 12000 on clock yes 12k on it and one of the cylinders was not getting as warm as the others . i should say no smoking on engine when running . SO I THOUGHT COMPRESSION TEST BEEN THROUGH ALL ELECTRICS. pilot was a bit blocked though on carbs off . well i had to make up a longer lead to get in their passed frame cross bar. the offending cylinder 115 psi whot! .So I checked all others the same eh eh. No bleeding shrader valve in end fitting into head. so I’m effectively increasing volume like you said (thanks for video regards john uk
No problem. Go buy a proper gauge!