Author Topic: 372xp (Read 2110 times)

Knute · « **on:** March 09, 2010, 08:00:44 pm »

Can you tell me what to expect the compression to be on a new or nearly new 372xp

Rocky_J · « **Reply #1 on:** March 09, 2010, 08:19:45 pm »

In 30 years I've never put a compression tester on a chainsaw, but I'll take a guess and say at least 150 once the rings are seated. That usually takes 4-5 tanks of fuel (working, not idling).

Knute · « **Reply #2 on:** March 09, 2010, 08:32:33 pm »

Thanks. I see used saws advertised and often they will list the compression. Without knowing what the compression is on a newer saw, I don't know if it is good or not.

flushcut · « **Reply #3 on:** March 20, 2010, 08:32:19 am »

It is around 150psi and from what I've hear. They tell you that is has compression so that way you know that it is not burned up.

joe_indi · « **Reply #4 on:** March 20, 2010, 08:47:36 am »

With the switch off and the decompression valve pushed in, pull on the starter smartly.
If the decompression valve pops up, you have decent compression.
Simple eh?

Cut4fun · « **Reply #5 on:** March 20, 2010, 09:43:53 am »

I wouldnt really go by de-comp pushed in and it pops open when pulled through as good to go. 365 with 115psi pops the de-comp just fine and it was worn out. This was with switch on and it burped.

HolmenTree · « **Reply #6 on:** March 20, 2010, 10:51:43 am »

On the 576XP AT s I have the button pops out when running.
Willard

Rocky_J · « **Reply #7 on:** March 20, 2010, 11:09:24 am »

Quote from: HolmenTree on March 20, 2010, 10:51:43 am

On the 576XP AT s I have the button pops out when running.
Willard

Isn't that what it's supposed to do?

$:-\$

JohnG28 · « **Reply #8 on:** March 20, 2010, 11:19:28 am »

I thought the same, aren't they supposed to pop back once it starts?

HolmenTree · « **Reply #9 on:** March 20, 2010, 09:01:19 pm »

Quote from: Rocky_J on March 20, 2010, 11:09:24 am

Quote from: HolmenTree on March 20, 2010, 10:51:43 am
On the 576XP AT s I have the button pops out when running.
Willard
Isn't that what it's supposed to do?

$:-\$

Easy boys, I was just relating to Joe's earlier post. Joe said with the ignition switch off crank engine over quickly and valve should pop up.
My 090 AV decomp pops up automatically, its spring loaded

Willard.

HolmenTree · « **Reply #10 on:** March 20, 2010, 09:08:48 pm »

Quote from: joe_indi on March 20, 2010, 08:47:36 am

With the switch off and the decompression valve pushed in, pull on the starter smartly.
If the decompression valve pops up, you have decent compression.
Simple eh?

Thats very true Joe, my 372XP has a "loose" decomp valve too. It pops out on its own too without the engine running.
My 576s have a rubber grommet sealing the valve button in the top covers hole, so I guess thats why its a little stiffer to pop out.
There now I can rest my case

Willard.

JohnG28 · « **Reply #11 on:** March 21, 2010, 10:06:16 am »

I dont run a larger Husky with a decomp, just my Stihl has it, and I hadnt noticed it popping when cranking, only once it burps or turns over, thats what I meant. I wasnt trying to say that you guys werent right, just hadnt seen this before.

Cut4fun · « **Reply #12 on:** March 21, 2010, 12:53:21 pm »

Quote from: JohnG28 on March 21, 2010, 10:06:16 am

I hadnt noticed it popping when cranking, only once it burps or turns over, thats what I meant.

You got me thinking, I dont think any of mine pop the de-comp with switch off. I will have to go check and get back. I got them from 130-150-160-170-180 and up.

Rocky_J · « **Reply #13 on:** March 21, 2010, 01:05:39 pm »

If you have a saw that will pop the decomp button with the switch turned off, then you need a new decomp.

HolmenTree · « **Reply #14 on:** March 21, 2010, 01:08:48 pm »

Quote from: Rocky_J on March 21, 2010, 01:05:39 pm

If you have a saw that will pop the decomp button with the switch turned off, then you need a new decomp.

No as Joe says "switch off and crank smartly"

Willard.

JohnG28 · « **Reply #15 on:** March 21, 2010, 01:22:33 pm »

Im not trying to argue or say your not correct, but on the Stihl Ive cranked it accidentally without turning on the the switch to run position, and the decomp stayed down until I switched to run and it turned over.

Cut4fun · « **Reply #16 on:** March 21, 2010, 01:34:07 pm »

Quote from: joe_indi on March 20, 2010, 08:47:36 am

With the switch off and the decompression valve pushed in, pull on the starter smartly.
If the decompression valve pops up, you have decent compression.
Simple eh?

I just tested this theory. Switch off and on 2 saws that have 180psi and another with 190+psi. de-comps did not pop off no matter how smartly I pulled them over.

joe_indi · « **Reply #17 on:** March 21, 2010, 02:58:05 pm »

The keyword here is smartly.
What I mean is more force that the usual starting force.
Ground start position is not good.
Between the thighs is better.
Okay there is another thing .
This test was what I do for Stihls.
The Husky de-compression valve has more air through flow than that on a Stihl.
Could this be the reason why its not working?

Cut4fun · « **Reply #18 on:** March 21, 2010, 03:11:02 pm »

I was doing Huskys. I will go try on my Stihls now too. Yes I was pulling VERY SMARTLY

, alot harder as if I was checking compression.

JohnG28 · « **Reply #19 on:** March 21, 2010, 03:12:55 pm »

That could be why we're not getting same results. I almost always use the thigh position, and I pull pretty hard, but I dont yank on it in an attempt to pull the cord right out, dont need any avoidable repairs.

Cut4fun · « **Reply #20 on:** March 21, 2010, 03:16:44 pm »

2 Stihl 084 didnt pop either , one stock psi, one with monster psi. Yes I pulled very smartly.

066 dont have a de-comp and no longer have a 361 to test.

But I do have extra 361 and 066 de-comps I could put in my high compression Huskys to test that theory too.

JohnG28 · « **Reply #21 on:** March 21, 2010, 04:40:15 pm »

Cut4fun, the saw I speak of is a 361, just getting nice and broke in, high compression...doesnt pop till running

Rocky_J · « **Reply #22 on:** March 21, 2010, 04:44:16 pm »

I would say that Joe Indi has a couple bad compression release buttons. The supposed technique he suggested to test compression does not work, or at least it should not work. Maybe he's using inferior mix oil and the compression release valves are plugged up with carbon?

Cut4fun · « **Reply #23 on:** March 21, 2010, 04:50:40 pm »

Quote from: JohnG28 on March 21, 2010, 04:40:15 pm

Cut4fun, the saw I speak of is a 361, just getting nice and broke in, high compression...doesnt pop till running

I'm just testing Joe's theory's is all. I dont think that way he suggested works.

JohnG28 · « **Reply #24 on:** March 21, 2010, 05:10:27 pm »

Is there any chance that the placement of Husky decomp valves could have anything to do with it, as the ones I can think of come out the side of the cylinder, as opposed to Stihls placed on the top? Just thinking of possible scenarios that could be a variable here with the different results we seem to be getting. I doubt that this would be the case, but just a thought.

Cut4fun · « **Reply #25 on:** March 21, 2010, 05:47:49 pm »

Quote from: JohnG28 on March 21, 2010, 05:10:27 pm

Is there any chance that the placement of Husky decomp valves could have anything to do with it, as the ones I can think of come out the side of the cylinder, as opposed to Stihls placed on the top? Just thinking of possible scenarios that could be a variable here with the different results we seem to be getting. I doubt that this would be the case, but just a thought.

I have none to test on for that, 361 044 046 066 (Somebody try it for us). Even the stihl 084 even though on the top is really off the side of cylinder too.

JohnG28 · « **Reply #26 on:** March 21, 2010, 06:06:02 pm »

Well like I said, on the 361 it works normal, just when running. I know the valve is ofset to the right side of the cylinder, but still appears to be on top. I was thinking of how the Huskys have the valve down lower and coming horizontally out the side.

Cut4fun · « **Reply #27 on:** March 21, 2010, 07:05:45 pm »

Quote from: JohnG28 on March 21, 2010, 06:06:02 pm

Well like I said, on the 361 it works normal, just when running. I know the valve is ofset to the right side of the cylinder, but still appears to be on top. I was thinking of how the Huskys have the valve down lower and coming horizontally out the side.

Are you saying with the 361 SWITCH IN OFF POSITION you can pull it over SMARTLY and the DE-COMP WILL POP OFF?

Mark K · « **Reply #28 on:** March 21, 2010, 07:11:39 pm »

I tried today to get my decomp. to pop off with the ignition off. I can't get it to pop off unless I turn the switch on. This was on my newer 372 that I use just about every day. My ported 046 won't pop off either until it trys to start. I imagine that them decomp. buttons can get worn over time.

Cut4fun · « **Reply #29 on:** March 21, 2010, 07:45:27 pm »

Quote from: Mark K on March 21, 2010, 07:11:39 pm

I tried today to get my decomp. to pop off with the ignition off. I can't get it to pop off unless I turn the switch on. This was on my newer 372 that I use just about every day. My ported 046 won't pop off either until it trys to start. I imagine that them decomp. buttons can get worn over time.

Thats good enough for me. Enough silly testing of de-comps and compression with off button

Thats what a gauge is for anyways and $25 is all too.

HolmenTree · « **Reply #30 on:** March 21, 2010, 07:57:53 pm »

Geez I had to go and try my 372 too. I think Rocky is right I need a new decomp valve. Its pretty loose. I watched it while the saw was running up to WOT and it didn't go back in to open on its own.
Willard.

JohnG28 · « **Reply #31 on:** March 21, 2010, 08:26:43 pm »

Cut4fun, what I meant was that on the 361 the valve will only close when the saw starts running. It will not close with the kill switch in off position.

Cut4fun · « **Reply #32 on:** March 21, 2010, 09:00:41 pm »

Got it now.

joe_indi · « **Reply #33 on:** March 22, 2010, 09:23:03 am »

Gosh!
I never thought that I would have nearly the whole forum pulling away at their saw starters trying to get the decomp valve to pop up.

My last reply here was at 12 midnight it was only today that I could tried to verify why the de-comps are not popping.
What I figured out is the following.

1. This test seemed to work only on Stihls, because the Stihls have the Decomp on the cylinder dome.Huskys and many others have the valve as JohnG28 pointed out, lower down on the cylinder. Stihl valves pop while the piston has just about reached TDC while as Husky A.O. pop while the piston is hurtling down on the power stroke.
So this test will not work on saws with decomp valves located on the cylinder wall.
So my original reply to Knute regarding the 'decomp valve test' was wrong, my apologies to Knute and any Husky owner who have been pulling at the starters trying to get those valves to pop. This test does not work on Huskies.Sorry once again.

2. I usually do this test on saws that really need a compression test. .Not a new saw or a perfectly working saw,
A saw which needs a compression test dose not have a spanking new decomp valve, Just an average working unit.
So, with the spark plug removed and a squirt of oil inside and the plug back in place, a couple of slow pulls to get that oil around and, finally, that smart pull.
If the decomp pops, the saw should have compression to run some more.
If the decomp does not pop, I attempt to start it up at that point, it should start but will usually die once all that oil smoke has cleared because just that oil was aiding the saw attain that extra compression.

Quote from: Cut4fun on March 21, 2010, 07:45:27 pm

Thats what a gauge is for anyways and $25 is all too.

I have no gauge to test the compression on a two stroke and they are not available whatever the price.So I have to make do with something like this as an alternative.

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Author Topic: 372xp (Read 2110 times)