MS362 low compression?

[Bardo]

This is my first post. I have learned a lot looking around this site. I bought a compression gauge today from Auto Zone (Actron). And tried it out on my MS362. The best reading i got was 128psi the worst was 120psi. I think i know how to test it correctly- I put it on the operating position- took the air filter off- and gave it full throttle- and pulled it several time until the pressure didn't go up anymore. I tried many different combination and it didn't seem to effect the out come of the pressure much. I tested the gauge against my air compressor- it was fine. The saw is only a couple of weeks old and has 3 to 5 tanks through it. Also i live at 5000 ft elevation. I read here some where that every 1000 ft the pressure drops 3%. So that would be 128psi * 1.15 = 147.2psi (at sea level).

So my questions are.

Is this pressure low?
Do i need to give it more time to break in?
Also how dose altitude actually effect horse power? (I cut mostly at 9,000ft-10,000ft)


Thanks Brandon

 

[brages]

I got an AutoZone loaner compression gauge and it says my saws are 105-psi.

 

[Bardo]

I got an AutoZone loaner compression gauge and it says my saws are 105-psi.

I don't know. I tested it with my air compressor. It was set at 90 psi and that is what compression gauge read. I have a rubber tipped air nozzle and i shot some air in the gauge.

 

[blsnelling]

I used an Autozone guage for a good while. It worked fine. Yes, altitude negatively affects all internal combustion engines.

 

[Trigger-Time]

Does it start easy?
Does it seem have good power?

I have had my share of troubles with tester!





!

 

[ttyR2]

I don't trust the KB Tools tester I have. It reads 5psi off compared to my air compressor, but two different saws I've tried it on (a Stihl 026 and 031) both read exactly 105psi which is hard to believe. It does have the correct Schrader valve in the end. Not sure what the problem is.

Could it be from having a longish hose on the pressure tester? Mine has an 18" hose on it.

 

[Bardo]

Does it start easy?
Does it seem have good power?

I have had my share of troubles with tester!





!

It starts fine and it seems to have noticeably more power then my MS290 (I just sold this saw). So I'm just not sure if I'm missing out on power- Because i cant compare it to another 362.

 

[cutforfun]

I have one that the most compression i can get on any saw is 130, If it gets there they all run great? Not much help but, it is how i trouble shoot old saws i get. Why are you checking conpression on a new saw(do you think something is wrong) just wondering

 

[Trigger-Time]

It starts fine and it seems to have noticeably more power then my MS290 (I just sold this saw). So I'm just not sure if I'm missing out on power- Because i cant compare it to another 362.

Don't want to steer you wrong, but your saw isn't even broken in yet.
It will gain more power until about 15 tanks or so.

Let me ask this, if you hadn't done a comp test would you
thought anything was wrong with the saw?

If you can bury the bar and it keeps pulling, I'm betting your gauge is off.

Or take it back to dealer and tell them the deal, ask if they have a gage.
If they do a test make sure and ask if you can watch and go from there.


TT


TT

 

[litefoot]

Your saw is fine. Enjoy! :biggrinbounce2:

 

[67L36Driver]

Your saw is fine. Enjoy! :biggrinbounce2:

Yup, most likely.

From my own stable:

Xl-2................135 psi
Runs good but sucking air at WOT and has .029" crank endplay.

Eager Beaver 2.0 top handle......................145 psi
Saw is like new with very little use.

Eager Beaver 2014 2.0........................135 psi
I was thinking this one needed a P&C but not anymore.

Craftsman/Poulan 36cc...........................125 psi
Average used saw. Runs excellent.
Real shocker as it is the newest model. Possibility it has a lower compression ratio than the older types for junk gas.

Method:
Used my Craftsman guage w/hose and cranked untill the guage needle stopped going up. All at room temp. Throttle blocked open, natch.

The 427 in my vet cranks 175-180 psi and C.R. is 9:1. Cam duration is not longish.

 

[wigglesworth]

I have had my share of troubles with tester!

Me too. My current tester says all my saws are 150psi, even ones that I "KNOW" are pushing 200psi.

 

[Bardo]

Thanks to all that replied.

I probably wont worry about the compression. I had no reason to think anything was wrong. I was just curious. And was surprised with the results.

Thanks, Brandon

 

[67L36Driver]

Compression ratio = Swept Volume / Clearence Volume

You will get a lower than expected pressure reading with a hose because the inside volume of the hose adds to the clearence volume of the cylinder.

It is much more apparent on a tiny chain saw engine than It would be on my BB Chebby.

 

[mtngun]

I bought a compression gauge today from Auto Zone (Actron).

Is this pressure low?
Do i need to give it more time to break in?
Also how dose altitude actually effect horse power? (I cut mostly at 9,000ft-10,000ft)

Providing your tester has the schrader valve at the tip, then it is probably working fine and the 128 psi result is probably accurate.

No, compression is not going to go up much with a few more tanks of gas. Maybe 5 psi. It doesn't take that long for cast iron rings to seat.

Yes, altitude reduces compression and HP. At 5000 feet, you're not going to get the same numbers that other AS members get. At 10,000 feet, you saw will be a dog. Fact of life.