My compression tester showed up today

[user 122190]

$20 and free shipping. Damn if it don't look the exact same as many others I see. The threads seem a bit rough so I'll try and smooth those out a bit before threading them into my saws. I'm certain this is pirated from production lines in China, and only being relabeled or not labeled at all.

http://www.amazon.com/gp/product/B014P3OIUU?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00

 

[USMC615]

Is there a difference btwn the compression testers labeled 'automotive engine use' and the compression testers labeled for 'two-stroke engine use'? They certainly look the same in functionality to me.

 

[user 122190]

The smaller combustion chamber of the saw could pose a problem. This kit does have a Schrader valve near the thread that attach to the cylinder head, minimizing the potential problem.

 

[A10egress]

$20 well spent. I've yet to meet anyone as hard on equipment as my older brother. He's heck on Craigslist, buying junk and not taking care of it making it even junkier junk. Anytime he asks me to check something out my comp gauge is the first thing i grab, then a spark tester.

 

[Okie]

Is there a difference btwn the compression testers labeled 'automotive engine use' and the compression testers labeled for 'two-stroke engine use'? They certainly look the same in functionality to me.

Yes, one of the main differences is the shrader valves in the 2 cycles is not same design, the springs are weaker.
Therefore the automotive gauges will usually not be accurate on small 2 cycle engines.

 

[lone wolf]

Yes, one of the main differences is the shrader valves in the 2 cycles is not same design, the springs are weaker.
Therefore the automotive gauges will usually not be accurate on small 2 cycle engines.

Well automotive works ,just takes more pulls.
http://www.klemmvintage.com/squish&comp.htm

 

[Okie]

Well automotive works ,just takes more pulls.
http://www.klemmvintage.com/squish&comp.htm

Automotive may work, but most not correct. You better prove to yourself that they are working correctly, especially if they are reading low.
I have tested several of my automotive compression gauges on small 2 cycle engines and most of the auto gauges will read around 35-60psi when the compression on a actron or snap on is 150 or more. (and this is turning over the engine until the gauges reached a max)
I would recommend that if you are getting low compression readings on a 2 cycle engine and you are not familiar with your gauge (you have not proved that the comp gauge will read correctly) you will feel even worse when you take the engine apart and the problem is YOU and your test eq instead of the engine. This compression testing issue is also briefly mentioned in the link.

That is a very good article link you posted about squish and compression!

 

[VA 372xp]

My harbor frieght unit seems work great

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[VA 372xp]

What ever happened to hold saw buy pull cord method for testing compression?

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[lone wolf]

What ever happened to hold saw buy pull cord method for testing compression?

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That aint as accurate.

 

[Okie]

That aint as accurate.

Using the pull rope method. Almost as accurate and trustworthy as trusting HF stuff. (and I have some HF stuff is how I know this)

I was checking compression on a little homelite awhile back, it would briefly start up when cold during first few pulls of rope if little bit of gas was added to the spark plug hole, but once it ran this out it would not pop again after adding fuel, good spark and plug would be wet, compression would check at 75 after several pulls the rope would extend itself by the weight of the saw. The saw would pop and briefly start again usually if it was just let rest for 4 hours or so. The saw looked rough also, could see where Bubba had been molesting the saw. (It was give to me for use as a parts saw) I had another little homelite that would start and run/cut good that only had 85psi and same carb setup. Out of curiosity and before doing a crankcase vac/leakage test or throwing the saw in the used parts pile I installed the carb from the saw that was starting and running good onto the problem saw and it started in 3 pulls and cuts and runs/idles good. (big surprise all at once, even scared me when it started)
Installed a cheapie carb kit and all ok. Seen where Bubba had been into the little carb making incorrect bend adjustments when I went to install the kit. Moral of story: Some saws don't have to have ultra High compression (over 100 or 125 psi minimum as some would think) to start easy and run good if all else is ok.