Saw idle ?

[alexcagle]

I have been thinking about it and wondering if deleting the gasket would change the tune just enough to throw it off? It seems to be running well otherwise

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That is a good question.

I would guess it might need to be a tad richer, but it may be ok "as is".

There are many factors that affect tune. Engine efficiency, fuel quality, temperature, air filter condition, spark arrestor, carbon buildup, humidity....etc, etc
I rebuild so many saws that it's a given that the tune will need to be changed from how it was tuned at it's last encounter with a repair shop.
I always check base settings prior to starting them. Sometimes out of desperation, people try to tune the saws in an attempt to get them running.

 

[Artemis]

I agree your high and low sound like they are out not perfect. I may have a similar issue, if you could even call it that. my 372 runs fine, the only hiccup is when it's idling, it will idle normally for about 3 seconds, then it will idle maybe 50-100 rpm higher for a second or two, and it will keep going back and forth between the RPM'S. It's a little annoying that it doesn't idle just smooth, but it's not killing me. hopefully yours is as it sounds, just idle adjustment.

 

[alexcagle]

I agree your high and low sound like they are out not perfect. I may have a similar issue, if you could even call it that. my 372 runs fine, the only hiccup is when it's idling, it will idle normally for about 3 seconds, then it will idle maybe 50-100 rpm higher for a second or two, and it will keep going back and forth between the RPM'S. It's a little annoying that it doesn't idle just smooth, but it's not killing me. hopefully yours is as it sounds, just idle adjustment.

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That sounds like an air leak from play in your throttle shaft.
I see that on higher hour saws.
See if you can wiggle it up and down any. If it does you can usually get away with just replacing the throttle shaft.
They wear faster than the bore does in my experience.
That or your main jet nozzle check might be "fluttering" and not sealing well enough at idle, thus, backfeeding air through the idle circuit making it leaner momentarily.

 

[Artemis]

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That sounds like an air leak from play in your throttle shaft.
I see that on higher hour saws.
See if you can wiggle it up and down any. If it does you can usually get away with just replacing the throttle shaft.
They wear faster than the bore does in my experience.
That or your main jet nozzle check might be "fluttering" and not sealing well enough at idle, thus, backfeeding air through the idle circuit making it leaner momentarily.

Mine only has 38 hours on it, so it's basically new. It has a muff mod but that's it. you sure a new saw would have an air leak?

 

[alexcagle]

No, I'd Maybe say it's not a throttle shaft.

Just curious, but maybe its your tank vent reaching the point where it lets some air in, causing it to fight the carb metering valve diaphragm ?
Most that I test reach a pound or two of vacuum before they open and then shut.
Maybe not.
Just thinking.

 

[Artemis]

No, I'd Maybe say it's not a throttle shaft.

Just curious, but maybe its your tank vent reaching the point where it lets some air in, causing it to fight the carb metering valve diaphragm ?
Most that I test reach a pound or two of vacuum before they open and then shut.
Maybe not.
Just thinking.

So it must be some sort of issue to do with air and not fuel adjustment? if I could solve it now maybe it will save me a headache later. I'll check the tank vent. thanks

 

[Artemis]

I found the problem. Turns out the main idle was set just high enough that the saw was right on the edge between idling and ready to go full throttle. As soon as I turned the idle down a little, the floating between rpms stopped and it was idling smooth again. I didn't think the idle sounded too high to begin with, but I guess it was just a hair too much. thanks for the brainstorming anyways guys.

 

[Big_Wood]

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That sounds like an air leak from play in your throttle shaft.
I see that on higher hour saws.
See if you can wiggle it up and down any. If it does you can usually get away with just replacing the throttle shaft.
They wear faster than the bore does in my experience.
That or your main jet nozzle check might be "fluttering" and not sealing well enough at idle, thus, backfeeding air through the idle circuit making it leaner momentarily.

his is an XT. some are so bad it's rediculous. i have one that i just tuned to run best and have been running it that way. i'm tempted to try a WJ69 on mine with gutted strato.