Did I destroy B-n-L's Craftsman 18"?

[Mo Heat]

I know, everyone hates Craftsman saws, but I could use some help understanding what happened and if there's something I can do to fix this thing.

I screwed up and put 32:1 in a 40:1 saw. Cheap big box oil, too. Didn't know that was an issue until a few posts ago. It's embarrassing, but I didn't have my glasses out there, I don't use the saw much, and unfortunately, this kind of stuff is happening to me more and more, and it definitely sucks. I probably have plaque building up in my brain, but I can't figure out how to floss it.

Anyway, here's what happened as best I can remember...

The first tank of 32:1 ran great cutting small stuff until I got near empty and the throttle seemed to stick (not mechanically, the trigger still pulled in and came out), the RPM's stayed high, close to full throttle, and the kill switch was slow to shut things down. I figured it overheated and was self detonating like a diesel engine or something.

After cooling, I refilled with 32:1 (dammit) and burned half the tank, all the while it refused to slow to idle speed.

The next week I was to cut some 22 inch oak logs with the B-n-L. He kindly pointed out that I had a can of 32:1 in the trailer instead of 40:1 so we dumped the tank and refilled. A test start was good, but the high throttle condition remained, although it would eventually come down to idle with some patience.

The first few 22" cuts went fine. Then the saw bogged down and stopped without there being a pinch or bind. It then refused to start. We knocked off for the day. Both of us with sore shoulders from pulling the starter cord endlessly.

Next day I go back for a second try. Saw starts okay with a few more pulls than normal. Cuts almost through one 22" log and bogs and dies again with no pinching. Like the motor just decided it had had enough. Another shoulder marathon won't restart the thing and I give up for the day.

Next day I go back again. Saw starts okay with a few more pulls than normal. I finish the previous day's nearly completed cut and start a fresh 22" cut. I'm almost through the log when it bogs and dies with no pinch or bind. Again the motor just seemed to decide it had had enough. Another sore shoulder workout won't restart the thing. I go home.

Pulled the plug and it was predictably fouled. Replaced with new plug. Cleaned, dried, and oiled the air filter. Noticed throttle trigger pin is slightly protruding, but not enough so as to seem to be a real problem. I push it home. Test start requires a few more pulls than normal. I go to my 22" oak log, make almost one full cut, and same old, same old, she's down for the count.

Did I fry this thing using 32:1 instead of 40:1? Or is it just a Craftsman in its death throws after a few years of light use? Time for a new saw, or is there a fairly simple trouble shooting procedure I might follow with a little luck. Any suggestions beyond not putting 32:1 in a 40:1 saw?

 

[brad068]

I highly highly doubt that that small of a ratio difference did damage to the saw. I just sounds like the carb needs some adjustments. Once again, as I've stated before remove the plastic caps covering the mixture screws and tune the saw to operating conditions not EPa- lean then out as to pass emission. low speed screw @1 to 1.5 turns out and about the same for high speed screw good starting point.

Make sure that the throttle lever on the carb is hitting the idle adjustment screw. It might also be a air leak in the crankcase causing it to lean out and start hard but more likely a carb issue. If this all checks out the carb probably needs a cleaning.

 

[computeruser]

The oil has nothing to do with it; it can run just fine on 50:1, 40:1, 32:1, assuming you are using modern oil.

Agreed - if the throttle moves fully, then it's probably an air leak. Pull the muffler and take a look. If you've got scoring on the piston and/or cylinder wall, then it might be time to look for a new saw.

 

[kenskip1]

The very first thing that I would do is check and make sure the gas tank vent is free of debris. A compression check should now be in order.If compression is OK, then I would suspect a weak ignition coil. Here is what happened to me.Saw was running great. then it did what you described. Well the carb kit was a waste of money. To cut through the lard and get to the bone, it was a weak coil. As the coil heats up it looses some of its voltage. After it cools down it would start and run fine. Until it got hot.

 

[BrotherBart]

Don't know what's wrong with the saw Mo but it wasn't the oil. I run 32:1 in the 65cc Poulan (have for 18 years), the little Poulan and both of the Huskies with no ill effect.

 

[TruePatriot]

Mo,

Rest assured, you cannot damage a 40:1 engine with a 32:1 mix, for the simple fact that you ran MORE oil, not less. 32:1 is a RICHER oil mix than the 40:1 the saw calls for--assuming, no offense, you mixed it correctly, and the "little red jug" wasn't really more than one gallon. I say that b/c, in mixing a batch for the neighbor-kid's gas-powered skate board, :roll: upon closure inspection, his "little red jug" was really a gallon plus 8oz., or some such. But even then, as was said, (and as a small engine technician friend of mine has also said) with modern oils, most things can be mixed to various ratios with ill effect.)

The ONLY thing too much oil could do is carbon-foul your ports, and I highly doubt that happened because your mix wasn't mega-rich, and you didn't run that much through it.

I think your "dieseling" suspicion is correct--I've had saws rev up high and REFUSE TO SWITCH OFF when they were running too lean due to an air leak--they overheat and begin to fire without the plug.

If you can stand the taste of gas, do what I did and blow into the tank neck, and listen for the leak--if you hear air escaping anywhere, then you know you've got a leak-to-atmosphere, and it's time to start dissassembly so you can hunt down the leak. IOW, if you can blow OUT, the saw can suck IN, thereby diluting the gas/air mix, making it too lean, and causing the overheating condition. That may, in turn, be causing a vapor lock--or it's just angry with you.

I bet you find an air leak.

But I would check that tank filter, too. See post #6, here, for discussion of a leaking "impulse" line: https://www.hearth.com/talk/threads/18808/#203418.

See post #7 in the above link, for discussion of how to remove and clean the fuel pickup filter.

Good luck.

TruePatriot

 

[Beanscoot]

Does the saw use reed valves? If so, maybe they're weak or fouled.

 

[brad068]

I don't know if this craftsman uses reed valving. But if reed valves are stuck open or broke you won't be able to start the engine. Reed valves are basically a one way check valve used to "check" air instead of a fluid. Engines designed with reeds will not operate without them. On a standard 2 cycle engine the piston skirt does the "checking" off of the intake port to allow downward pressure from the piston to force the fuel/air mix to the top of the piston thru the transfer ports thus into the combustion chamber. When you get into snowmobile engines and dirt bike engines you can see some real ingenious designs on both intake and exhaust valving.

All in all this saw sounds like an air leak some where in the bottom end or a restriction in fuel.