How to Perform a Compression Test on a Harley Davidson : Pro Tip

See more tips and how to's on Countersteer : www.jpcycles.c...
Diagnosing engine problems can be the most difficult part of getting your bike running properly. Doing a compression test is a great way to narrow down possible issues with your machine. If you are experiencing a lack of power or looking to isolate an issue down to a particular cylinder a compression test can be very helpful.
#CompressionTest #HarleyDavidson #ProTip

[@jpcycles]

Looking for more tech tips and installations? Head over to Countersteer for more : www.jpcycles.com/countersteer?How_to_Perform_a_Compression_Test_on_a_Harley_Davidson_:_Pro_Tip&E2UCTsQ-dSM&feature=youtu.be

[@dustinbarnes9206]

You can hold your hand behind the exhauast as a quick check and feel for a difference between the front and rear cylinder compressions. I'm in the habit of doing as the last step to pre-ride. First thing youll notice on almost any (air cooled) v-twin that has been really ridden a few thousand miles is that the rear cylinder starts pushing a little less than the front. But the point is to get a baseline feel for your bike so you have a heads up if it dips noticeably between rides.

[@chrishunter5041]

Made my tester out of modified spark plug and a tyre pressure gauge, thanks for the post 👍

[@shanecodman1842]

Made in America ride on brother. Flat earth

[@thechristianbiker812]

Tell me how to make one please

[@234234234werrrrrrr]

Great video, thanks.

[@CPerreault]

My 2006 Deluxe reads 125 psi on both cylinders. The manual says the lower limit before service is 90 psi. What should the PSI be when the engine is new? What is your take on the manual's lower limit and my current compression? I have 50k miles on the bike. Would a cylinder overhaul be in order?

[@ludditeneaderthal]

Why didn't you oil the low piston? Cold doesn't tell you much to begin with, and a few squirts of oil showing a marked improvement shows the problem is ring/bore related

[@CarlosGarcia-ls4hn]

What is the procedure when you have compression releases?

[@fffanman]

Should the motor be warmed up to have proper clearances?

[@jpcycles]

You can perform a compression test cold or hot, if you are looking for a potential issue its best performed cold.

[@csiautodetail]

what about if you have 4 spark plugs? do you have to disconnect all of them?

[@robedmunds7163]

Does it hurt the electronic ignition turning it over without the plugs grounded?

[@jpcycles]

no

[@williamwhitlock2701]

i have a 2001 ultra classic. i get a puff of smoke out of my rear cylinder when i let off my gas. compression in rear is 140 front is 150. could 10 psi diff maybe be valve seals. thank you much

[@boscodog4358]

Will my 2017 HD Heritage Throw a code if the compression release is NOT OPENING at start?

[@CarlosGarcia-ls4hn]

When you mention ratios like "10-1" what does that mean?

[@tattooglisha]

Did you open throttle?

[@CarlosGarcia-ls4hn]

What would be too high compression for stock cams? (2000 113 ci Springer)

[@vicmotoFXDL]

Hello sir, where is the link to the compression tester?

[@KemDIY]

Is the compression tester specific to Harley or can you use any car one too? Assuming the only thing is having the correct thread. Did you have a link to the tester you use?

[@jpcycles]

The tester was an automotive version that comes with different attachments

[@grimeyhonkyracing3938]

How much of a difference in compression between the two cylinders is within the normal range?

[@ludditeneaderthal]

No more than 10%, preferably within a few psi

[@marcnunes6916]

M8 are over 230ccp no?

[@kingdomnate6906]

Oh great, I just did this and had ZERO compression.

[@ludditeneaderthal]

Then you have a bent valve, a holed piston, or didn't install the Guage properly