Compression Tester

[fischer550]

Can somebody post a link to a cheap but reliable compression tester that will fit an ada head? Thanks

 

[DAG]

There is no such thing as a cheap "and" reliable compression tester. I have about 5 cheapo's in my toolbox. They are only used to compare 1 jug to the next. The actual numbers are meaningless.

 

[fischer550]

Alright then one that is affordable and will get the numbers correct enough

 

[Ducky]

This is the one that I have found to be the best for the cost. It is a re-branded Matco tester.

http://www.amazon.com/OTC-5605-Delu...647804&sr=1-1&keywords=otc+compression+tester

 

[Jetfiend]

I picked up a nice Snap on on Ebay many years ago.

This Motion Pro looks nice for the $

http://www.motorcycle-superstore.co...as=2&zmam=20213228&zmap=42226&P_ID=3030372126

 

[Quinc]

I have tested my harbor fake cheapo compression gauge against a snap on gauge a couple times months apart and was within 1lb each other.

 

[Ducky]

I have tested my harbor fake cheapo compression gauge against a snap on gauge a couple times months apart and was within 1lb each other.

And my harbor freight reads 10-15 psi low lol. I take that thing with me when I go to look at skis to get the price lower because of "low" compression lol.

 

[Quinc]

That's cold blooded! lol

 

[SUPERJET-113]

I have a Craftsman, middle of the road in pricing I would say($60). Any kit you buy will have all the adapters you'll need for any spark plug size or length.

 

[kevbo]

There is no such thing as a cheap "and" reliable compression tester. I have about 5 cheapo's in my toolbox. They are only used to compare 1 jug to the next. The actual numbers are meaningless.

Cylinders never wear or fail at the same rate. A compression check is useful only for comparison. The schrader valve deteriorates over time, your cheap gauges will work like new with a fresh 99 cent valve.

 

[RMBC Freeride]

Location of the schrader valve is critical too. If its way up near the gauge (usually is on cheap units), or even an inch up the line because of an adapter for your threads, then it is essentially adding to your dome volume and skewing your readings. So it would only be good for cylinder-to-cylinder comparison purposes as stated above.

 

[krisxone]

Location of the schrader valve is critical too. If its way up near the gauge (usually is on cheap units), or even an inch up the line because of an adapter for your threads, then it is essentially adding to your dome volume and skewing your readings. So it would only be good for cylinder-to-cylinder comparison purposes as stated above.

Never thought about that, good point.

 

[augustaf]

Extremely (!) important is the type of "Schrader" valve. A tire valve takes way to much force to depress and will give a low reading. Your friendly Snap on man usually carries the proper valve- which is used in the pic. Don't be put off by the unusual looking gauge, checking it's calibration proved to be more accurate than a megabucks gauge from McMaster.

 

[makejetskiinggreatagain]

That's cold blooded! lol

I was gonna say the same thing lol

 

[SXIPro]

My Harbor Freight cheapo matched my brother's Mac lb for lb initially. It's 3 yrs old now and there is a 20 lb difference between mine and my brother's. So, like a lot of HF stuff, if you're just gonna use it once, you'll be fine.

 

[JetManiac]

Technique also matters alot. Blue and I tested with 2 guages and different techniques one time and got 40-50 lbs. difference in readings depending on method used and which guage.

You can only measure the cranking compression not the actual running compression at higher rpms. Holding throttle open and removing the other plug will increase cranking speed and give more accurate readings. Make sure battery and cranking speed is strong.

Remember that a newly built motor with unseated rings and no oil will not give accurate readings. A little oil will help get a reading but too much and reading will be way too high.