How To Test Your Motorcycle Engine Compression 

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

Check valve clearance before test

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

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 :)

Great vid. Thanks for

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.

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

Thanks bro, very helpful!

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

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 RU-vid guys like you.

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

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

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!

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

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

What if it’s a carbuerated engine and you still open the throttle all the way

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

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

Hi I'm trying to do a compression test on an 01 Yamaha yz426f. Are able to help me out. I got 88 PSI on the gauge. I'm at 6035 ft. What would it come out to?

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

Do I have to take both spark plugs out? Mines a 2 cylinder. 4 stroke.

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

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 RU-vid 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!

As I can see, you're using in this video cheap, Chinese no name tester for 20$. That's why you got low compression results.

What should the compression values be in a YZ450F 2019 and a CRF 250R 2020?

Sounded like my air box was farting/popping when i had throttle wide open and didnt do it with throttle closed. Any ideas? Ktm300xc 2022

What should the compression be on a 1977 Hodaka Wombat 125cc that won’t start

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)?

2013 kx450 supposed to have how much compression closed throttle closed?

How much psi should a rm 250 two stroke have

amazing video thank you💪💪💪💪

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.

What if you have a manual decompression lever do you hold it done while your doing the test ?

i think my compression tester is broken.. it gave me 70psi on a running 125cc 4 stroke dirt bike, and 60psi on a 150cc gy6 quad... and 50psi on a banshee (that does have a problem i think it wont move onder its own power) but it starts and idles.. but yeah i think my meter is broken... eveyr thing is between 50 a 75psi...

i just rebuilt a 93cr125, i have not run the bike yet so its not broken in, but im getting only 100psi compression. i had the cylinder honed and measured with the cylinder its in spec ring is gapped and oriented correctly. bad gauge or just not a full seated ring? having trouble getting bike to start

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

Drain Carb and fuel line, turn off petcock?

I should have done this before buying my 3 dirt bikes lol

Man im gonna say my IT250 with 100 psi is no good, runs great once you getter goin but you gotta take a nap after kickin so many times

How much should a 2018 yz250f have

I have a 2018 crf250R I’m getting 75 psi compression I was wondering if that was good or bad thanks

If my r6 compression is 35/40/180/180 can it still be saved? Or does this mean i need a new engine?? I hope you see this and reply! thanks!

How do I do this and NOT have my bike start... cause that happened lol

Brilliant!

Why the need to hold throttle open and ground out the plugs?

I’m only at 130ft elevation should that affect my psi ? Your chart starts at 500

When you put oil in the spark plug hoke to see if a top end rebuild is neccessary. Do you just use regular engine oil on it?

Does everyone no how much psi of compression a 2008 Crf150rb is supposed to have

Been reading that using the Estart to check compression is really hard on the starter. Is this true? If yes, how can I check my compression with a bike without a kick start and a rekluse?

It looks so easy skipping how to take out the spark plug!

When you have the tester compressed and start the motor, how does the air stay in the cylinder. Won't the air escape out either the exhaust or fuel valves while rotateing the motor?

Will the compression test also determine the compression ratio?

hey the test was carried out on a cold engine or a warm one??

It's better test engine compression with hot engine, rings and cylinder hot