Poor man's compression test?

[artie__bc]

For saws, just pick them up by the starter handle. If it has enough compression to hold itself up without the rope pulling out it's either seized or has great compression. Usually the saw will slowly 'chug' its way down the rope. If it drops quickly, put it back on the shelf and keep your wallet in your pocket. Make sure the decomp is closed, though!

 

[gee_dubya75]

How do I edit a post? There is no 'edit' icon visible to me in my post above even though I'm logged in.

I had a question about the compression of a Makita DCS 6401 but I left off the 4 accidentally.

 

[Rookie1]

How do I edit a post? There is no 'edit' icon visible to me in my post above even though I'm logged in.

I had a question about the compression of a Makita DCS 6401 but I left off the 4 accidentally.

Well I think with this reply members will figure it out,if thay havent already.
Edit, I kooked this up on FAQ.
If you have registered, you will be able to edit and delete your posts. Note that the administrator can disable this ability as he desires. Your ability to edit your posts may also be time-limited, depending on how the administrator has set up the forum.

 

[lone wolf]

tech question on test?

any input on doing test hot or cold or how ambient temp changes readings?

 

[stihlboy]

room temp is best, if cold you lose some compression because the rings arent expanded fully

 

[handyrandyrc]

I picked up a cheap 11-dollar compression gauge from Amazon.com and tested. Just a hair over 130 PSI! I think my thumb was a fairly good indicator of where things were at.

 

[spacemule]

Compression tester World !

It should have its own forum and I already named it! LOL


I know alot of guys on here love their compression testers and their minimum
compression reading for a saw to be a runner.
IMO its pretty much pointless , I you cant tell from pulling over a saw and the way it runs if it has good compression, you should get an electric saw and then you dont have to worry. Also all of these saws that are torn down or junked because they blow under 150 what a waste . And the myth a saw wont run with under 120 is just that a myth. Its very easy to start a saw and see if it is strong or not.
!

That's what I've been saying for years. I wonder how many of the saw geeks on here wear pocket protectors.

 

[andym]

I've been fighting with a Poulan Pro 260 and just tested the compression. I guess 40psi is too low ehh? This saw is like brand new too.

 

[Arrowhead]

Is this one at Baileys decent?

http://www.baileysonline.com/itemdetail.asp?item=G+320HD&catID=

I'm thinking about buying a used saw this next week and would like to check the compression before I buy it. What kind of compression should a Makita DCS 601 have?

Where are some places that one could by a compression tester locally? Does Autozone carry something like this?

I have that one from Baileys, I like it.

 

[Nandy]

Well, If you want to know if you have good compression the only way to do it is with a compression gauge, nothing less...

 

[Anthony Pillois]

Compression tester World !

It should have its own forum and I already named it! LOL


I know alot of guys on here love their compression testers and their minimum
compression reading for a saw to be a runner.
IMO its pretty much pointless , I you cant tell from pulling over a saw and the way it runs if it has good compression, you should get an electric saw and then you dont have to worry. Also all of these saws that are torn down or junked because they blow under 150 what a waste . And the myth a saw wont run with under 120 is just that a myth. Its very easy to start a saw and see if it is strong or not.

Next I'm gonna invent a chain sharpness gauge, it will be computer operated and it will scan your chain cutters and if it says no good you just throw it away. It will save all that silly stuff like feeling your chain or trying it in wood that's all a thing of the past. If you dont have a sharpness tester before long you will be a rookie!

I agree with you on the low compression I did a video on utube with a comparison between a Mac 1010 that I knew had 150 lbs of compression and a Poulan pro 5020av that I got over two years ago that then only had 30 lbs of compression at the end of the video I started up the Poulan its under Anthony Pillois low compression check it out

 

[JohnsonD]

And now for the poor man's ignition tester. Simply put your pinky in the spark plug boot and pull the cord.

 

[lone wolf]

And now for the poor man's ignition tester. Simply put your pinky in the spark plug boot and pull the cord.

That works pretty good actually.

 

[Anthony Pillois]

And now for the poor man's ignition tester. Simply put your pinky in the spark plug boot and pull the cord.

that's one way of doing it with shocking results lol another is just lay the plug on the head and pull the rope

 

[Little Al]

120# of compression may be good on a snowmobile, but not on a saw.

Got to agree anything below 150psi is a bit on the weak side for a saw also a "redneck check for compression" is hold the recoil handle & let the wight of the saw hang free if it pulls the start cord out in a series of jerks the the saw saw has compression how much is a different ball game I have 2 ALPINA saws the prof 55 has 225 psi compressiom & the 070S has just north of 200psi

 

[lone wolf]

Yeah !!!!! What he said ........... Who needs compression anyways?? I think its over rated at best.

Instead of making pop-up pistons and increasing compression, I'm going to dish out my pistons to lower the compression. I'm sure they will run a lot strong after that.

A lot of times when I compression test a saw and its running over 150 psi. I'll dishout the piston to bring the static compression down to something more mangeable like 120 psi. It makes for an easier starting saw, while simultaneously increasing the amount of time I get to spend running my beloved chainsaws, because it takes longer to get anything cut. Perfect concept.

Thats what I do,

Sam

But can you do all that precisely without a gauge?

 

[lone wolf]

I rebuild MS 200T saws and sell them would a buyer be satisfied if I told him it passed a drop test? I bet he would not! I have 2 gauges one Snap On the other US Gauge and I calibrate them together with the gauge on my shop compressor and they all read the same so I say they are pretty accurate! Also I have a Snap On adapter for the smaller plugs and it took a while to dial that in I had trouble with adapters before this one then I had trouble with the wrong Schrader valve finally I got it calibrated.

 

[Riles32807]

I worked as a bicycle mechanic for a while. I cringe when someone pinches a tire and tells me there's enough air in the tire. I think I have a reasonably strong grip and I can't tell the difference over about 15 psi. Most mountain bike tires take 35 psi or more, road bikes usually take 65+.

If your on the spot looking at a saw to buy and fix, the thumb test, or the drop test might be useful to get an idea of whether it's worth your time and money. But its not useful as a diagnostic tool.

 

[Dennbb]

Yeah !!!!! What he said ........... Who needs compression anyways?? I think its over rated at best.

Instead of making pop-up pistons and increasing compression, I'm going to dish out my pistons to lower the compression. I'm sure they will run a lot strong after that.

A lot of times when I compression test a saw and its running over 150 psi. I'll dishout the piston to bring the static compression down to something more mangeable like 120 psi. It makes for an easier starting saw, while simultaneously increasing the amount of time I get to spend running my beloved chainsaws, because it takes longer to get anything cut. Perfect concept.

Thats what I do,

Sam

Good way to go. Compression ratio is more critical that high compression. Using a 162 husqvarna as an example. The squish at .031 calculates to 13.7 : 1. With the squish at .021 it's 16.2:1. Anything over 14:1 is deisel territory and gas will ignite from the compression. Which is why gas in a deisel engine will grenade the engine. Most saws stock are 11.5 - 12.5 for a reason. They don't want to reach the deisel threshold. I was taught 45 years ago to never assume that the engineers don't know what they're doing. I'd be willing to bet that 70-90% of ported saws on the internet have less power than stock if they were all dynoed. There's a placebo effect in loud saws.

 

[Cantdog]

Good way to go. Compression ratio is more critical that high compression. Using a 162 husqvarna as an example. The squish at .031 calculates to 13.7 : 1. With the squish at .021 it's 16.2:1. Anything over 14:1 is deisel territory and gas will ignite from the compression. Which is why gas in a deisel engine will grenade the engine. Most saws stock are 11.5 - 12.5 for a reason. They don't want to reach the deisel threshold. I was taught 45 years ago to never assume that the engineers don't know what they're doing. I'd be willing to bet that 70-90% of ported saws on the internet have less power than stock if they were all dynoed. There's a placebo effect in loud saws.

Hmmmm.....well good luck with that.......we'll see what the respondents say....LOL!