MZ360. What is compression in psi?

90 to 110 psi

I have a 123L Husqvarna String Trimmer that wont start. I...

http://answerarmy.com > posts
May 21, 2018 - First the compression is way too low as most 2 cycles require at very minimum of 100 psi to start and most trimmer when new usually have between ...
Missing: chart ‎' Must include: chart

• 
  

  Husqvarna 324L 4 stroke trimmer has 90 psi compression

  http://answerarmy.com > posts
  Mar 13, 2018 - Husqvarna 324L 4 stroke trimmer has 90 psi compression, won't start on starter fluid, and owner says he always has to run it on partial ...

How to Troubleshoot a Husqvarna Weed Eater - Hunker

https://www.hunker.com > ... > Garden Tools & Supplies
Note the compression levels, which should be between 90 to 110 psi for a good engine. Service the compression and air systems if the reading is below this. Step ...

135psi is the low end but anything around 140 to 150 psi is really good engine for 1.6 l, i would check the timing is right as this can affect the compression.

normal compression readings will be in the 150-165 psi range
There is a permissible 10% differences between adjacent pistons
anything below 120 psi is considered worn engine
really low readings on 1 cylinder indicates
broken ring
scored bore
bent valve
burnt valve
loose valve seat insert
low readings between adjacent pistons indicate a head gasket

It should be between 120 psi, and 150 psi , but shouldn't vary more than 10 % between cylinders

It could be a problem in the valve train. For a car that old, before putting new parts in, you could buy a compression tester for about $30, and do your own compression test. It should tell you if the engine is good enough internally to warrant proceeding. If compression is low on any cylinders, that problem must be addressed first. If a valve is not sealing and causing the popping, that cylinder will show low compression.
For the test, the engine should be at normal operating temperature. Then pull all the plugs out, connect tester to #1 spark plug hole. Have a helper hold the throttle wide open while cranking the engine over about 5 seconds. Watch the gauge-the first revolution or two will cause the gauge to jump high at first, and successive revolutions during the 5 second span will cause the needle on gauge to climb a little each time. Record or note the compression on #1, then do each cylinder. Try to do the same amount of cranking on each cylinder, and keep the throttle wide open. What you want are compression readings on each cylinder that is well above 100 psi, and all should be close. The lowest reading should be within 75-85% of the highest reading cylinder. Example: say your highest reading is 135 psi. 85% of 135 is 115-so your lowest reading should be at least 115 psi. Some general guidelines: any cylinder with compression below 100 psi is definitely a problem-that cylinder will not have hardly any power output, even if it is firing. Worn piston rings or poor valve sealing is causing compression loss. A newer engine should have compression readings above 150 psi. As the engine wears, compression will drop. In general, for high mileage engines, you would want to see compression in the range of 125-150 psi, the higher the better, but remember, it should be balanced-the lowest should be at least 75% of the highest reading cylinder.
Post back if you have questions-good luck.

Compression is too low, it sounds like there is a head gasket failure. The compression should be above 100 psi as a minimum. Normally should be in the 120-170psi range.

Hello
Well i always do the easier method to find out the problem.
hers a few things to do to determine whats wrong.
1st pull spark plug and do compression test, a blown head gasket will lose compression.
if the gasket is blown then the compression test will read a low psi and drop suddenly
2nd worn piston rings will lose compression, the compression test will read a very low psi below 100 psi and may leak right down depending on how worn the rings are.

that would make you lose power.
have it tested to see which it is.

either way, a lose of power in the motor is caused by lose of compression in the motor.
you can do the test your self, you can buy a compression tester pretty cheap, just make sure you don't cross thread the connectors.
have a good weekend
Big Al

The compressions you mentioned...Good?
No. Not at all.
Those compression reading indicate either really bad/worn piston rings, or valves that are not sealing properly, or both.
Normal compression readings should be at or above 140 PSI, +/5 5 PSI difference, no more.Save your money, and look for another unit. This engine is going to cost you a lot of money to make it right.

Minimum compression is 100 psi @ 200 rpm. The lowest cylinder reading should not be less than 80% of the highest reading. Perform the compression test with engine at normal operating temperature, spark plugs removed and throttle wide open. Normally I look for about 170 psi to 180 psi.