Author Topic: 4000 rpm's  (Read 1165 times)

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Offline redunshee

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4000 rpm's
« on: January 28, 2014, 04:42:43 pm »
Some may have read my issue with a 4000 I just picked up. I wonder if I have a going the wrong route.  I've been trying to adjust the Hi speed at around 10,500 using a tach.  I know many of you don't use a tach but without wood here to really test the saw this is the next best approach. I'm beginning to think the 4000 may run at higher rpm's than a 3400.  Can anyone confirm or debunk my thinking. I always check plug color but again w/o wood to really run the saw under load I doubt I'm getting accurate plug color feedback.

Bob

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Offline Cut4fun .

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Re: 4000 rpm's
« Reply #1 on: January 28, 2014, 04:48:34 pm »
Seems low.
My 4000 I never checked with a tach. I just set to 4 stroking and then backed it off till it just barely stopped four stroking.  Ran great no idea on rpm's. Least I dont remember if I did check. 

Video of it in thread.
http://chainsawrepair.createaforum.com/poulan/poulan-4000/msg29283/#msg29283

Ray Benson =  I keep a log on my saws for setting the high speed screw since getting a tach. The poulan 3700 hasn't been run for a couple seasons but it ran best when set it at 11,500. Just follow the owners manual recommendation when setting the carb. Tach isn't really necessary.

Offline 3000 FPS

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Re: 4000 rpm's
« Reply #2 on: January 28, 2014, 07:33:06 pm »
Bob I do not have a 4000 but I have some 3700's and 395's.    I always tune them to wood and never checked them with a tach.    Tomorrow it is suppose to warm up some and I will do some Checking for you.

Roger
PP 505, 475, 445.

Offline 660magnum

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Re: 4000 rpm's
« Reply #3 on: January 28, 2014, 11:03:39 pm »
These older designs work great to tune in the wood by ear.

Some of the newer "Strato" type engines have a very slight two stroke-four stroke break and even a old timer has to really listen to tune a "Strato" by ear particularly if it has a limiting coil.
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Offline Eccentric

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Re: 4000 rpm's
« Reply #4 on: January 29, 2014, 01:02:58 am »
I tune most of my saws (including that series) by ear.  Don't even own a saw tach right now.  I'll have to borrow my bud's tach to see what my 4000 is turning just for a baseline.  I set them so they're 4-stroking at WOT unloaded, but clean up when under moderate cutting load.  When cutting load's lifted, I like them to go right back to four stroking.  That's my "general setting" for most of my saws (including my PP375 and 4000).

If tuning a saw for limbing or 'small wood' cutting I run them a tad leaner than that.  I get them to where they just continuously 4-stroke at WOT unloaded, and clean up as soon as there's light-moderate cutting load.  That's how I tune my small saws (unless I'm going to be asking them to 'cut above their class'........like doing a bunch of 12"-16" cutting with my S25-CVA).  In that case I richen it up just a hair.

If running bigger bars in bigger wood, I go a bit richer, so that the saw doesn't completely run 'clean' until under full load (bar length or greater wood).....................with just a bit of 'off and on' 4-stroking under light-moderate cutting load.   That's mostly on my bigger saws wearing 30" and bigger bars.

I need to get a tach for the times that I'm tuning other guy's high-revvin' modern saws.  I tend to run my saws a tad richer than some guys do.  Better safe than sorry.............and with good synthetic oil at 32/1 I still don't get any carbon buildup.  I'm not racing, and long saw life is important to me as I'm on a budget.8)
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Offline 660magnum

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Re: 4000 rpm's
« Reply #5 on: January 29, 2014, 01:14:41 am »
+1
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Offline 3000 FPS

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Re: 4000 rpm's
« Reply #6 on: January 29, 2014, 02:28:51 pm »
Ok I put the tach on my PP 395 and on my Poulan 3700.   Both saws had the bar and chain on them and wide open throttle.

The PP 395 has been MM and the base gasket removed but no other mods.  The RPM's were at 10,600.

The Poulan 3700 has been MM and the base gasket removed with another .020"  taken from the base and then the intake and exhaust ports were widened.   The tops of the transfers were pointed towards the intake side and the plastic intake manifold was smoothed out.   The timing was advanced also.  The RPM's were 13,000.

Both saws were 4 stroking with no problem.
PP 505, 475, 445.
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Offline redunshee

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Re: 4000 rpm's
« Reply #7 on: January 29, 2014, 04:30:16 pm »
Wow, 13,000.  Wouldn't dare set mine that high. Really miss having wood around here to tune my saws. All I have is my ear and tach.
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Offline 3000 FPS

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Re: 4000 rpm's
« Reply #8 on: January 29, 2014, 04:34:21 pm »
I hear ya.   Both of those saws were tuned by ear in wood and is where they happen to end up at.
PP 505, 475, 445.
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Offline hotshot

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Re: 4000 rpm's
« Reply #9 on: January 30, 2014, 09:31:31 am »
What is insane is the fact that the caged needle main bearings used in them are only rated for 6500 RPM in oil,
that's at their full dynamic loads of course.  The actual running loads must be lower, as these saws run forever, if
maintained correctly.

 

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