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Craftsman -Poulan saws trashed by new owner

cranman1951

cranman1951

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Greetings friends....my first post , although been lurking for years. I happened on a stash of new Craftsman saws when my local sears closed up. 3218 and a lone 4620. I sold the 4620 to a man on Market place two days ago and he was using it to cut a large Walnut tree that day. He called an hour later and said the saw lost power and wouldn't restart....he brought it back, it had no spark, and I sent him home with the last 4218 I had. Called back an hour later with same complaint, I took the 4218 back and gave him back the 4620 with a coil stolen from a junk 240 Husky....hour later the 4620 crapped out again! I told him to bring it back and refunded his money. Yesterday I tore into them both and both had less then 20 lbs compression and deeply scored pistons.. I sent them out full of gas oil mix ( Husky xp) at 40 -1, and it appears he didn't add any fuel. What happened???? I don't believe I had any air leaks and I always adjust a little on the rich side for the carb tuning. Did the OP over rev the saw and fry them because they hadn't been broken in yet? First time I've seen this.
 
merc_man

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Welcome to the forum.
Are you certain you put mix fuel in them? I would pour a little of you gas you put in then in a clear container to see.

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cranman1951

cranman1951

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Yes....I had just filled a new can and put 1.8 gallons high test and a 2 gallon mix of the Husky xp oil. Gas mix when I checked it was dark blue as it should be. I'm going to dump what was left in the saws out just to make sure the OP didn't add straight gas. He honestly didn't have the saws long enough to run the tanks dry, and I topped them off every time he came back.
 
cranman1951

cranman1951

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I've always used the 50-1 ratio with my Huskys and Poulan -Huskys until this last fill, with no issues since 1980. I only increased the ratio this time due to some posts here, and the fact that I had several saws with new piston/cylinder replacements I thought would benefit from the added oil.
 
Old2stroke

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I always adjust a little on the rich side for the carb tuning.
Are you sure it was rich enough? Was it 4-stroking at WOT out of the cut and just barely cleaning out in the cut? Not sure about the 4620, but the other 2 are Poulan strato saws and most of them are failing like yours did because they are just running too lean under power. Strato saws can be tricky to get tuned to a safe setting.
 
cranman1951

cranman1951

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I'm sure that you are right....I can't imagine that the saws could see so much damage if they weren't running lean.....I try to adjust the carb's to run at the richest setting that will run smoothly...how should I go about tuning so this doesn't happen again?...again, the mix was close to 40-1
 

Derf

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Sounds like an air leak caused a lean seize.

If the mix was made correctly, I’d guess that there was a problem between the carb and the cylinder, but crank seals could also just be old and shot.

If the saws were ever taken apart, perhaps they were put together wrong and something was missed. If they were new but old, maybe a rubber boot hardened and wasn’t sealing well between carb and cylinder.
 
merc_man

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I'm sure that you are right....I can't imagine that the saws could see so much damage if they weren't running lean.....I try to adjust the carb's to run at the richest setting that will run smoothly...how should I go about tuning so this doesn't happen again?...again, the mix was close to 40-1
At WOT out of the cut you should here it burble (four stroke). When you put it under load in wood the burble should just turn smooth.
When i adjust the low side i start little rich so when comesnoff WOT it kinda stumbles. Then i slowly leannout till tHE stuble.goes away after WOT.

hope this makes sence. Im not the greatest at explaining some things lol.

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SteveSr

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I'm sure that you are right....I can't imagine that the saws could see so much damage if they weren't running lean.....I try to adjust the carb's to run at the richest setting that will run smoothly...how should I go about tuning so this doesn't happen again?...again, the mix was close to 40-1
40:1 is LEANER than 50:1! More oil is LESS gas! What were these saws designed for? 50:1? This could be part of your answer.
 

KASH

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Let me get this right you are saying that the heavier I mix my oil the less lube the motor gets.If what you say is true that the extra oil can not get threw the carb to lube the motor where does the extra oil wind up? I have never saw oil remaing in the gas tank and I have run several old Evinrude outboards that call for 2 pints to the gallon and my old Pioneer Da runs on 12 to one lots of smoke but no oil build up.
 
champion221elite

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A lean mixture has nothing to do with fuel to oil ratio. 40:1 has more oil in a given amount of fuel but will result in a lean condition since the air/fuel mix is off. Lean is a reference to air/fuel mix where there is not enough fuel available for a given amount of air.

Lean/Rich is purely air/fuel related. It has nothing to do with lubrication oil ratios.
 
Old2stroke

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It doesn't matter what your oil/gas mix is as long as the saw is tuned to run on that mix ratio. If you change the ratio, then the carb has to be retuned. Pay no attention to claims that you have to run 50:1. Without starting another oil war, those saws will run just fine using a good oil mixed at 30:1 (what I use) or 40:1 and give better bearing protection without carbonizing the top end, as long as the saws are tuned to run at the sweet spot under power. Correct tuning is the critical thing. I have posted before with an easy way to achieve this, I'll see if I can find it and repost it.
As mentioned above, a lean condition can be caused by air leaks as well as improper tuning and these can be eliminated by pressure/vacuum testing. I have rebuilt sooo many of these box store Poulans that have failed because of scored top ends, and so far have found none that failed due to air leaks, always because they come from the factory with the high speed mix set too lean combined with inexperienced operators who are abusing the saw by trying to make it cut with a dull chain.
 
cranman1951

cranman1951

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I'm of the mind that it was the OP trying to cut with a dull chain....the sawdust that was on the saw was very fine, and the chain was dull when he returned them. The saws were two years old but almost new and never taken apart. I didn't retune them after changing the mix to 40-1 however, as they sounded and ran well.
 
toolmaker

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It doesn't matter what your oil/gas mix is as long as the saw is tuned to run on that mix ratio. If you change the ratio, then the carb has to be retuned. Pay no attention to claims that you have to run 50:1. Without starting another oil war, those saws will run just fine using a good oil mixed at 30:1 (what I use) or 40:1 and give better bearing protection without carbonizing the top end, as long as the saws are tuned to run at the sweet spot under power. Correct tuning is the critical thing. I have posted before with an easy way to achieve this, I'll see if I can find it and repost it.
As mentioned above, a lean condition can be caused by air leaks as well as improper tuning and these can be eliminated by pressure/vacuum testing. I have rebuilt sooo many of these box store Poulans that have failed because of scored top ends, and so far have found none that failed due to air leaks, always because they come from the factory with the high speed mix set too lean combined with inexperienced operators who are abusing the saw by trying to make it cut with a dull chain.
Please try to find it and repost. I would like to know your method.
 
Old2stroke

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The idle mix is adjusted just like a non-strato saw, usually about 1.5 turns out on the L screw to start then adjust for consistent idle with good acceleration when the throttle is snapped open. Idle speed should be set just below point where chain starts to move. The L screw adjustment has very little effect on the high speed adjustment but after getting the high speed set with a number of long cuts with the bar buried in wood, the saw will get cleaned out of any residual fuel and the idle may have to be readjusted.
I use a different approach to setting high speed screw. Start with the screw so far out (about 3 turns) that it smokes, blubbers, won't speed up and is obviously too rich to cut anything then screw it in 1/4 turn, make a cut and listen to see if it starts to clean out while cutting, which it won't at this point. Screw it in another 1/4 turn and repeat the cut thing. Eventually after a number of these repeats (probably 4-6) you will reach a point where the engine will start to clean out and run crisp at higher rpm part way through the cut, after the next adjustment this should happen as soon as the cut is started. Stop there and you have a safe setting for the longevity of the saw. NOTE: You will need a decent piece of wood ( 1' dia.or larger is good) so that you can keep the saw running under full power for a long time and use a sharp chain.
 

KASH

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I have been running chain saws old snow machines outboard motors for 55 years almost all have had adjustable high and low speed needles. all of these engines have been run on heavy mixed oil and lighter mixed oils.The only piece of equipment I ever had seize was A LawnBoy mower at 16-1 cutting 2 foot high swamp grass on a hot july day .Poured some oil down the plug hole cleaned the grass out of the cooling fins and wrenched it over till it was loose spray of gas in the carb throat and back to mowing.I am not to critical on the dead accuracy of my mix ratios old stuff and chain saws heavy mix.I have never had to do any critical fine carb ad justments due to a different oil ratio.With over 400 different pieces of equipment I would go insane adjusting carbs.The stuff with fixed high speed jets do not seem to run any different on various mix ratios.
When we were kids my brother filled the 5 gallon tank for a 9.5 Johnson and forgot to put the oil in we fished all day motor ran great. good thing there had been a gallon still in the tank.
Kash
 
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