372 carb adjustments

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Engineeringnerd

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My 372XP doesn't seem to "settle in" on it carb adjustments. I have a tach and have trouble getting it to precisely 13,500 +/- 200. I'll pull the trigger and get it to rev at 12000 one time, adjust it out, then it runs fine for a few seconds, then press the trigger and it sounds like its bumping the rev limiter. I've tried setting it lower (say 12,700), but then it begins to four cycle too much in the other direction.

No matter what it sounds like when adjusting the carb, it changes seems to have a mind of its own in the wood. I'm adjusting it while its hot after making a number of cuts. I'm going to check the carb later to make sure it's securely fastened, any other ideas?

I'm using good premium gas (with Stabil) mixed with Bailey's 2 cycle mixed 50:1. The saw has about 10 tanks of gas through it, but I've experienced this since day one. I've had saws "wander" over hours or as the filter gets dirty, but not between individual cuts. To be honest, even with my driver on the H adjustment screw, I don't seem to be able to get it to run as smoothly as it should.
 
Follow the fuel line from carb to filter, looking for bends, etc.., where the line might get partially crimped, and/or cracks. Then if you find nothing, look in the carb in case some crap may have been in the tank when new, and has partially now clogged the screen/ passage.
 
My 372XP doesn't seem to "settle in" on it carb adjustments. I have a tach and have trouble getting it to precisely 13,500 +/- 200. I'll pull the trigger and get it to rev at 12000 one time, adjust it out, then it runs fine for a few seconds, then press the trigger and it sounds like its bumping the rev limiter. I've tried setting it lower (say 12,700), but then it begins to four cycle too much in the other direction.

No matter what it sounds like when adjusting the carb, it changes seems to have a mind of its own in the wood. I'm adjusting it while its hot after making a number of cuts. I'm going to check the carb later to make sure it's securely fastened, any other ideas?

I'm using good premium gas (with Stabil) mixed with Bailey's 2 cycle mixed 50:1. The saw has about 10 tanks of gas through it, but I've experienced this since day one. I've had saws "wander" over hours or as the filter gets dirty, but not between individual cuts. To be honest, even with my driver on the H adjustment screw, I don't seem to be able to get it to run as smoothly as it should.

Just one question, is it old the 372XP? This have happen to me when my Jonsered 2152 was new, but after I have run a good deal of gas it was good.
 
Follow the fuel line from carb to filter, looking for bends, etc.., where the line might get partially crimped, and/or cracks. Then if you find nothing, look in the carb in case some crap may have been in the tank when new, and has partially now clogged the screen/ passage.

Take a good look at the fuel line.after you check the carb. bolts,
even look inside the fuel tank at the fuel line. it is coiled up like a pigs tail. so use something to move it around, could have a crack in it.
 
When the saw has about 10 tanks of gas through it, this is not normal, but remember you have to check the H and L adjustment screw to tune the saw to run good.
 
Mag,

It's a 2004, but I purchased from someone who hadn't used it (new) and started using it myself very recently. Didn't have any gas in it while stored, it was NIB.
 
Mag,

It's a 2004, but I purchased from someone who hadn't used it (new) and started using it myself very recently. Didn't have any gas in it while stored, it was NIB.

Something (fuel lines or gaskets) could have dried out if it wasn't used for 2 years (+), I believe......

I have been into saws for a long time, although on and off.
 
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Mag,

It's a 2004, but I purchased from someone who hadn't used it (new) and started using it myself very recently. Didn't have any gas in it while stored, it was NIB.

Check the fuel lines as the other here says, but when the 2152 I have was doing something similar, it was a bit to rich on carb settings. After a while I adjusted the H and L screw when it's was warm, a bit leaner. Understand that the engine can acting up some under the brake in period, and you must adjusted it. And remember that the H and L screw must be adjusted.
Tried this first and see if you can get it right, but bee careful.
 
O.K., I checked the carb screws, they seemed to be tight. I went ahead and took off the carb, checked the screens, all looked good. Removed the fuel line from the carb and took off the fuel filter, all looked pristine. Capped off one end of the fuel line with a finger and blew into the other end, no obvious leaks. Why is everything blurry now?.... Reinstalled carb, Loctited all screws. Went ahead and put on a new filter to cap the deal.

I believe the L screw was off a bit, as I was able to turn it counterclockwise about 1/8-1/4 of a turn to get max idle. Didn't have time to finish the job as it was getting dark and I really want to get the saw hot before making the final adjustments.

If the L screw was off, could that have seriously impacted High speed performance too? My thought was that the L screw impacts idle and the smoothness /quickness of acceleration, but has little to do with high speed performance once revs are achieved.
 
I have no idea if this is right, but close enough. Turn your low speed all the way in,then back it out 1 turn. Low speed is right when you hit the throttle and there is no hesitation, and the saw will run in all positions(upside down etc...) make sure the air filter is clean, exhaust bolts tight etc.. carb is not loose, check the linkage set up, check for broken or loose anti-vibe mounts. If the idle screw has been adjusted take it to the shop. Hope you can take care of it on your own though. If all this is wrong, keep in mind I am drinking my Christmas present from my brother, mixed with some grapefruit juice.
 
Carb adjustments

elmnut is close, but I will say it another way: turn the L screw to you have max idle, then counterclockwise about 1/8-1/4, then you adjust the H screw. Double check this, and whit the tach you have. And yes, the L screw have some impacts on the overall speed performance of the engine. And remember that this is whit a hot saw. When the saw is cold, you will maybe feel like it's a bit lean, but when it's hot it shod be close to perfect. ;)
 
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It's raining like crazy here, so I'm a little delayed getting on the saw. I did find the filter a little dirtier than I thought, so maybe that is playing into it. What kind of life do you get out of a filter before cleaning, and do you clean or just replace it. I'm using the pleated, high capacity felt filter.
 

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