A co-worker just picked up an 044 mag from an engineer at work, very gently used saw. He was having starting issues and took it to a local outdoor products shop, they said it needed a new jet (larger/smaller)? Our elevation is about 3700 ft and the saw lived at about 5000ft +-, is this a common problem? Thank you. I was first in line for this saw but couldn't swing it.
Looking at the IPL, there were two jets available for the Walbro carb used on later 044's. The standard jet is 0.66 mm, and the high-altitude jet is 0.64 mm. Earlier Zama carbs did not have multiple jet options. Assuming the saw worked well for the previous owner, I'm skeptical that a 1300-foot change in altitude would make a big enough difference to require changing the jet, and if it did make a significant difference I doubt it would manifest as starting difficulties. My money is on the problem lying elsewhere.
Since we know so little about this particular saw, maybe we could take this opportunity to describe starting problems we've seen in the wild? An o36 I had a year or so ago kept flooding no matter what techniques I tried to start it. If I was lucky enough to start it at all the it ran very poorly and wouldn't restart hot. Turned out that the previous owner had futzed with the carb himself, and put it all back together wrong. He'd broken part of the switch shaft that holds the throttle at high idle for starting, and also bent part of the linkage so that the choke was partially closed regardless of the switch position. After replacing the switch shaft and massaging the linkage (a steel wire) back into shape the saw started easily and ran fine. An 044 I recently acquired started fine at first, but bogged down under load. I looked at the carb first, and the gaskets and diaphragms didn't seem in obviously bad shape. Before reassembly I sealed the intake and rinsed some dust out of the air box, getting other parts of the saw wet in the process. After reinstalling the carb the saw wouldn't start at all. It turned out that the insulation had crumbled off of a couple inches of both kill switch wires by the coil, and the moisture I'd introduced had made the sawdust packed around those wires conductive enough to short out the ignition. I disconnected the switch wires from the coil, and it started fine. After fixing the wires, that same o44 had a tendency to flood if allowed to idle for long, and once flooded it was difficult to restart. I took a closer look at the carb, pressure-testing it this time. It failed. Suspecting a leaking inlet needle, I cleaned the carb and replaced the needle, metering lever, gaskets, diaphragms, etc. The saw now starts easily both hot and cold, and the idle is stable. Woo!
I would find it hard to believe it needs a different jet. Did they actually tune it or just look at it?
Might need to clarify your description some for a better guess. When you say it won't start, does it run for ANY amount of time or just a small pop? Run a little with Choke on? From my limited experience a saw will run some if jetted wrong. Start simple and try a plug from a known , good running saw or try your current plug in the good running saw. Make sure the crankcase isn't full of fuel too. Being an 044 that means it is old enough to have rubber line issues or cracks in the wires for intermittent shorts. Look them over VERY carefully. If you can, disconnect the kill switch once too. Let us know what you find. I've learned over the years to never trust a shop that didn't fix a piece of equipment. I've got some saws at a good price which they said had major issues and turned out not to be. We sometimes tend to look for something major when it is the simple thing. I start with compression test and work down from there.
1000 feet of altitude change will make a difference in the operation of the engine. When at 5000 feet the fuel to air mix needs to be reduced to compensate for the less dense air, move the saw to 3700 feet and you will need to increase the fuel to air mix because of the increase in air density. That being said, I don't think that it is the cause of the starting issues. When changing altitudes, the engine will run but will be either rich or lean when running. Keep in mind you are dealing with two ratios here that can be described as 'rich' or 'lean' mix oil to gas (Fuel) and Gas to air. Given that most if not all of the oil in the fuel is gone by the time the remaining gas/air mixture gets to the combustion chamber. This final mixture is the dangerous one, too lean you fry the top end, too rich no power.
A liitle more information; I started the saw in Abq, NM 5,350 altitude if ran fine, the saw went home to Amarillo, TX 3,700 altitude and the saw wouldn't start at all. Original owner location altitude 6500-7000 ft.
That's a bigger elevation change, but I still doubt the jet size is to blame here. Did you (or anyone else) adjust the carb? When it fails to start, does it not even burp/fire briefly on choke?
Yeah, this isn't because of the jet. The high-altitude jet is smaller, and would deliver less fuel. It wouldn't cause flooding. This sounds like an ignition problem. I'd disconnect the kill switch wire's spade connector from the coil, and try again. FWIW, both of the older o44's I got recently had the insulation crumbling off of their kill switch wires. The saw you're asking about is probably newer than mine, but might have the same problem.
Unless it's a trusted shop your "Surprise" may be in the bill. Shops have a way of charging you for all their guesses and then tell you it was a combination of things when they missed it off the start. My guess would be flooded crankcase now but ignition is what started the whole thing. He didn't by chance pull and pull it with the switch to the off position. Seen that before and makes for a flood situation and hard to get the first fire. That would trump the ignition.
Update; Saw owner was charged $40 for carb adjustment and saw cleaning, sounds like the saw runs well now.
