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550xp port job is running weird on 1st start….. help

pbillyi69

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do you have a regular non smart carb you can try? is there one that will work on that saw?
 

emanuel

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This is 100% a fueling issue (not enough fuel), either from an air leak of some kind or carb issue (malfunctioning solenoid, leak, clog).
When vacuum and pressure testing the saw make sure you spin the crankshaft so you don’t get a false positive. Pressure and vacuum test the fuel lines too, and the carb itself. Ultimately only once this is 100% passed you can think of the solenoid being the issue. Easiest test for that is swapping it from a friend’s saw.
 

dangerousatom

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Dont think its the solenoid as it passes all computer testing with the Husky diagnostic tool. My moneys on the carb having a leak or a bad jet. This is the reason I got a new carb coming. IMO Id like to have a baseline with a 100% good carb before I go back into the used carb even if I do find it leaking..

pbillyi69

do you have a regular non smart carb you can try? is there one that will work on that saw?

I dont believe there are any swap over non AT carbs that fit a AT-saw. It can be done but its lots of parts near 1/2 the saw minus the jug and body.
 

pbillyi69

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Dont think its the solenoid as it passes all computer testing with the Husky diagnostic tool. My moneys on the carb having a leak or a bad jet. This is the reason I got a new carb coming. IMO Id like to have a baseline with a 100% good carb before I go back into the used carb even if I do find it leaking..

pbillyi69

do you have a regular non smart carb you can try? is there one that will work on that saw?

I dont believe there are any swap over non AT carbs that fit a AT-saw. It can be done but its lots of parts near 1/2 the saw minus the jug and body.
copy.....what a pain in the patoot
 

emanuel

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Dont think its the solenoid as it passes all computer testing with the Husky diagnostic tool. My moneys on the carb having a leak or a bad jet. This is the reason I got a new carb coming. IMO Id like to have a baseline with a 100% good carb before I go back into the used carb even if I do find it leaking..

pbillyi69

do you have a regular non smart carb you can try? is there one that will work on that saw?

I dont believe there are any swap over non AT carbs that fit a AT-saw. It can be done but its lots of parts near 1/2 the saw minus the jug and body.
If the solenoid is not the issue, why bother with a non-at carb? Nothing wrong with autotune/m-tronic, especially now after they figured out the proper materials for the solenoids and they actually last (yea, plastic moving parts were *s-word, go figure lol). Its fine tuned and reliable, same with the 500i's injection system (probably even more reliable, I heard literally ZERO issues with the fueling system on these). Looking forward to an update after swapping the carb, fingers crossed
 

Nutball

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Maybe the ignition is bad, or the sparkplug, or a bad electrical connection somewhere? Loose decomp or loose spark plug? Could the transfers be shorting out the exhaust excessively from bad porting? Some sort of short between the intake and crankcase causing a free port backflow?
 

bogieboy

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If the solenoid is not the issue, why bother with a non-at carb? Nothing wrong with autotune/m-tronic, especially now after they figured out the proper materials for the solenoids and they actually last (yea, plastic moving parts were *s-word, go figure lol). Its fine tuned and reliable, same with the 500i's injection system (probably even more reliable, I heard literally ZERO issues with the fueling system on these). Looking forward to an update after swapping the carb, fingers crossed
First run of 500is had some issues where they would randomly lean themselves out to the point of siezing.... had 3 of them theu the shop for the same thing, got the rep in to look at em, and he said...yeah... we have seen that in the early run saws... put a new computer module and jug and slug in it and it will be good....
 

emanuel

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First run of 500is had some issues where they would randomly lean themselves out to the point of siezing.... had 3 of them theu the shop for the same thing, got the rep in to look at em, and he said...yeah... we have seen that in the early run saws... put a new computer module and jug and slug in it and it will be good....
Interesting, didn't hear about it in forestry crews here, and they started using them in 2019. When were your problematic ones acquired? Mine has fabrication date of 10.2019, it always seems to run rich enough, richer than the auto-tune/m-tronics at least by the sound of it, as did all the 500i's I used.
 

bogieboy

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Interesting, didn't hear about it in forestry crews here, and they started using them in 2019. When were your problematic ones acquired? Mine has fabrication date of 10.2019, it always seems to run rich enough, richer than the auto-tune/m-tronics at least by the sound of it, as did all the 500i's I used.
I couldnt tell you, i work in a stihl shop and have seen them come thru from other folks... can just tell you that i put em back together, and thry havent been back since....LOL you wouldnt catch me owning a 500 unless it was given to me for free.... and even then i would likely trade it for an ms462 or ms661.... i am not a fan of them, theres too much stuff that has the potential to go wrong in my mind...
 

dangerousatom

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Finally got around to the saw. :rolleyes:

Installed a new carb and swapped over the old solenoid bits and this saw already runs better then new. With a 20" bar and new chain I can lean on it with the bar burred in ash thicker then the bar. With the pop-up piston and gasket delete this thing should be a spectacular small firewood saw. I could not find any air leaks in the original carb after gasket/rebuilding it . I dont trust plunking it into water to watch for super slow leaks with the electronic bits. Im wondering if it was leaking where the solenoid and aluminum carb come together.

If anyone knows if the electronics are waterproof minus a gasket leak it be great to know.

Ill post up compression numbers after its broken in with a few tanks of gas.
 
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