Yamaha Compression Test

[@chriskiely126]

That guy is the best KZbin guy on Outboards I've seen yet

[@rhm504]

Erin, Thanks for the video. I appreciate the info, which is helpful. My background is not as a marine tech, just DIY'er kinda thing. At the end of the video, you ask why check compression with WOT, then add that it can give a falsely high reading. This info is useful. So (again) having little technical background with marine engines and just a little experience with a couple 100h services on my F200XB, I follow the Yamaha service manual to help me do things. Manual LIT-18616-03-53 page 0-6 under the "Conditions when testing and adjusting" section says "Throttle valve at WOT (depending on model specification)." Based on your experience, it sounds like I don't have to have WOT to get accurate readings, right? (I don't plan to wait until it's 68F outside and I don't live at sea level either, for whatever that's worth, heh.) Just trying to learn stuff and thanks in advance.

[@WTFisthis327]

Just compression tested my 2014 Yamaha F20. While leaving the throttle at idle, I got 90psi on both cylinders. While opening the throttle to max, I got 175psi on both. It seems there is pressure relief valve for starting that is held close when manipulating the throttle.

[@fishydubsfishing6516]

So what was the purpose of the compression test was there a performance problem on the engine

[@pastapaul150]

What is stopping fuel from being delivered? Thanks

[@NelsonVelasco-xw2px]

The Yamaha service manual for this motor states that the motor should be run for 5 min before starting the test. Also, the test is performed at wide open throttle.

[@atvdave88]

The yamaha manual states to open the throttle plates when doing a compression test, you want it to breath and suck in as much air as possible because theses engines are ran i open throttle

[@AchikSarih]

Merci beaucoup ❤❤❤❤

[@JustMike2791]

That looks like Matlacha bridge behind you. Did you guys just move? Lots of juvenile jewfish at that bridge but the tide almost always sucks. Thanks for the vid

[@gulfsidemarine2992]

Yes that is the Matlacha Bridge. We have moved into Cape Coral and are providing all of the same quality service and some new products as well.

[@daver2964]

Great video,! Want to ask 2 questions. Should I routinely check compression, let’s say on maintainence or if cold start or idle rough issues. Also, I noticed the spark plug were not numbered.? Should I re0lace them In same order they were removed?

[@gulfsidemarine2992]

Yes, checking compression at each service will warn you of possible issues. It does not matter what order you remove or replace your plugs. It does matter if one plug looks noticeably different from the rest when you remove them.

[@retpekp6624]

Hi sir. Can i ask about our yamaha 115. There is no speed

[@TeamBuckRogers]

To perform this test, is it necessary to remove the kill switch on the helm?

[@gulfsidemarine2992]

You should remove the kill lanyard from the switch to prevent spark or fuel from being delivered. This prevents fire hazards.

[@creolecannon3674]

Hey man quick question is a 130/140 on all four cylinders on a Honda 150 outboard normal compression ?

[@MK-fq4jn]

I have an older yamaha F25 (2006).. both cylinders read the same but they are low @ 98 psi. No idea of hours. She starts every time, doesn't smoke, Runs good. The issue is performance..i struggle to hit 15 knots, in my G3 Pro175. . Would this product or miracle oil work.

[@gulfsidemarine2992]

I would recommend confirming that the motor is not over propped and that the boat does not have any unnecessary weight before you make changes to the motor.

[@MK-fq4jn]

@@gulfsidemarine2992 confirmed Has original prop, its an electric start with tilt. I retested the compression and received better numbers top: 120 psi, bottom:105psi. Sparks gapped correctly, .

[@MK-fq4jn]

Should i try Seafoam and change oil afterwards to get rid of deposits. I really don't want to change anything just return compression and power. I really don't want to rebuild the motor, replace rings..etc

[@gulfsidemarine2992]

@@MK-fq4jn In my experience the usual causes of low power are some sort of contamination or malfunction of the fuel system or ignition. Low compression can cause a loss in power but usually shows up in a test. Seafoam will help clean the rings and valves. Let me know if you see any changes after the treatment.

[@cherylkellam4865]

What size compression fitting did you use? Bought a compression tester for my 2002 yamaha F90. No adapter would fit

[@gulfsidemarine2992]

Please give us a call if you have not found an adapter 239-282-0443. I will look at mine and get back to you.

[@lauracortez6745]

What are some of the reasons for low compression? Follow up video?

[@gulfsidemarine2992]

Low compression in these engines is caused by a valve issue or a piston issue. Overloading the motor with a high pitch prop or improper operation shortens the life of these motors.

[@carlosmarrero1382]

Im buying a 2012 yamaha 250 hp with 700 hours the compression is 180 psi u

[@carlosmarrero1382]

Is that compression good?

[@gulfsidemarine2992]

Carlos, as long as the compression was within 15psi between any two cylinders it should be good.

[@colleengram4374]

@@gulfsidemarine2992 I just got a Yamaha outboard motor 100hp 4 stroke, psi is 160/165 on each piston there good enough thanks