How To Test Your Motorcycle Engine Compression

The compression of an engine can tell you a lot about the overall health of an engine and help diagnose problems with internal components, such as pistons, rings, and valves. The Tusk Compression Tester allows you to perform a compression test on any gasoline engine with 10mm, 12mm, 14mm, or 18mm spark plug threads and features a quick disconnect coupling and air gauge for ease of use. In this video, Charles shows how to use the Tusk Compression Tester to perform an engine compression test on a 2-stroke and 4-stroke motorcycle.


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[HeAdChEeSe]

Great video! No stupid fluff introductions, advertising, or talking about things that do not matter. I am going to check my valve clearance this winter for the first time by myself and because of this video I can check to see if the rings are not tight too. I would like to do a before and after if I have to shim them. The piece on the oil was pure gold. I appreciate your videos and have had good luck with Tusk products in the past. I think I will buy that kit. Once again thank you. I would not attempt the valve job without YouTube guys like you.

[chandlersuddarth]

Let’s be honest we’re all here because we either have a pos or bought a pos

[rcktgirl]

Thanks for this video! I'm taking an online course for motorcycle repair and although it's thorough in procedure, it's not hands on so I'm always looking for videos to see what the text is talking about. You've got a new subscriber now :)

[jamiediseker]

I bought a wonderful machine for $100 and she's been nothing but amazing for me since she is a 2021 Blaze wolf moped Blaze 2 150cc absolutely amazing and inspiring on one side of the spark plug because there's some kind of a compression issue what's a cylinder that is the only huge issue I've ever had with her up-to-date right now which that is an issue at all God bless let's make the world a better place and not have poses in it anymore all it would take is some peace of mind

[draggsxr]

Can you tell me if the shraider valve is tight in the end piece. Most of these kits can’t do 50 or 65 cc engines. They don’t move enough air to seat the shrader valve.

[connersnow]

Awesome vid and edits and filming and tools and shop and bikes

[stefanhansen]

Awesome! So NO reason at all to inspect valves if the compression is in spec (even if the manual says valve inspection every x hours)?

[s.k]

What about bikes who has automatic decompression? Isn't those readings are false if test it with auto decompression?

[WOLFEY]

I have a Honda Xr80R 2000 my compression is 90 PSI and I was just wondering what you think it is I really appreciate it thank you oh and I started my bike cold when I did the compression test cuz it hasn't started since I bought it. Its a 4 stroke

[bobwa]

My bike is 70cc. How to know the maximum compression for my motorcycle? How much should be the minimum compression in terms of percentage.

[jamesgeorgevellavella]

When I screw in adapter I get 75psi? When I use the rubber I get 135-140psi. Do I have a defective tool? I’m thinking yes

[jerryx]

Can the Compression test show you why the bike uses too much oil?`

[evemizerrago]

How to buy this tester? How much equavalent in peso?

[dylantendoornkaat]

I did a rebuild because i had oil from the exhaust. Heads are redone, new piston rings without re-honing the cylinders because they still had a nice crosshatch and no visible damage. New seals and gaskets and exactly done as the manual says. Put back together and she runs fine only problem, still oil in the combustion chambers. As you can imagine this is frustrating me. Anyone any ideas on what this could be? I oiled the valve seals a bit to prevent cracking of the rubber but I'm thinking it could be the valve guides. Any help is welcome, thanks!

Best Compression test video I have seen!
Regards from South America and please excuse my wrong english.

May I ask to your knoweledge?

Should a compression test to show an increase of the psi sample on a brand new engine after 1.30 hours of engine break-in to make comparison?

Topic apart, Can you give me some lights about main Jetting and spark plug reading?

Here, local tech service has not O² sensor and empirical knoweledge seems to be not good at all.

I have seen plug chop test here on Youtube and I made my own test two times, two news spark plugs used without carbon deposits as results after test was made.
I understand that high rpm and temperature makes a spark plug cleaning, so plug shop makes sense looking for carbon deposits at bottom of insulator. Is that right?

I'm a Honda XR150L brand new owner and 5000 miles today, basic motorcycle but I notice that it comes so lean AFR. white spark plug readings and over heat...
I just want to be stoichiometric in low jet and slightly
rich on main jet.

I know about jetting, elevation and temperature range rules... I know about upper side of spark plug reading for low and middle throttle opening range but main jetting seems to have a special method like a plug chop test has.

All my setting is stock setting except the main jet. from #102 to #112 tested now.
150cc³.
20mm throttle bore.
stock jets #35 *#102* -> #112*
+/- 1500 ft asl and +/- 86°F.

Jet #112 tested does not shows any carbon deposit at bottom of insulator after cut it's body thread, nothing!

Plug chop was much more than 5 minutes at WOT, 6 runs avoiding low jetting and spark plug reading shows just a little brown mark deposits at top of insulator and oriented to the exhaust valve. NOTHING MORE!

What is the range of main jets number to test on this kind of engine and environment?

Is there a well known range number of main jet to emulate a 13.5:1 or 14.0:1 AFR values for example?.
What am I doing wrong?.
What information I need to know?.

Plug chop method is not known here in spanish tech community.
Thanks to you a lot!

[danilomartinezgonzalez]

Hello how are you
Could you help me with the proper value (psi) for the Honda CRF250R - 2014?
Thank you

[tittyrino]

I have a 1985 Vmax and to do a compression test I cut the bottom off of an old spark plug and welded and air compressor fitting to it so I could check compression

[matt]

Honestly if you have a four stroke with auto decompression don’t waste your time with this tool. Use the leak down tester instead for an accurate. Wait till you get an adapter stuck in the plug hole too (good time there). Just buy a quality tester with multiple hoses.

[dallinjensen]

What should the compression specs be at normally for a 4 stroke

[Duke_]

What should compression be on a 2021 kx250? Similar to the intervals of this 450?