GT380 Carbs...

Post your problems / information on the smaller GT Models here
barney01
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Re: GT380 Carbs...

Post by barney01 »

Dave are you doing this from cold? It's a waste of time tuning the carbs unless the engine is fully warm and 'cleared out'.
When you say idle screw do you mean the small screw on the carb called the pilot air or mixture screw? The idle set screw is the big round one that sets engine speed.
The pilot air screw is used to fine tune the carb at low revs or idle according to atmospheric pressure. It does what it says and meters the amount of air in the pilot circuit turning it in clockwise allows less air therefore running richer. Turning out anticlockwise allows more air making it leaner. If the aircrew has no effect at all that suggests a clogged pilot circuit.
NO SMOKE .......NO POKE
Dbailey
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Location: Portsmouth UK

Re: GT380 Carbs...

Post by Dbailey »

Thanks guys...

It was done with the engine hot.. and yes I’m incorrect and should be referring to the pilot air screw. :P


Thanks
Dave B
barney01
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Re: GT380 Carbs...

Post by barney01 »

The pilot circuit in these carbs is not visible and on top of that there is a branch that exits in the mouth of the carb it's like a pinhole called the pilot circuit bypass. These are vital to smooth running at idle and low revs. It is very hard to make sure they are clean and it can take several runs through an ultrasonic cleaner to achieve this.
Can you just repeat what your running problems are? Cant see them in this post
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BAZ
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Re: GT380 Carbs...

Post by BAZ »

The outlet will not clean with an ultrasonic cleaner you will have to use a carb cleaning rod to clear it around .6mm, spray carb cleaner with the pilot jet removed to check. be sure to wear eye protection carb cleaner in the eye is not funny..if fact ultrasonic cleaners will not generally clear passageways just remove visible dirt.
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Gary66
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Re: GT380 Carbs...

Post by Gary66 »

Boil in a pan of water with lemon juice, my 380 carbs were minging and i mean minging! i boiled them for half an hour, the boiling water obviously agitates crud out. Just dont use the Mrss best wok as i did, i still have the lump on my head for using ours :D
Dbailey
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Location: Portsmouth UK

Re: GT380 Carbs...

Post by Dbailey »

Thanks guys.. more jobs for the list...

Dave B
barney01
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Re: GT380 Carbs...

Post by barney01 »

Just one word of warning. Not too long in lemon juice it will attack the surface of the alloy. Don't ask me how I know this :roll:
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Alan H
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Re: GT380 Carbs...

Post by Alan H »

Same reason as I know that using citric acid (crystals) solution does the same!
Maximum 2 x 10 minute sessions in the ultrasonic cleaner or the carb looks like it's got leprosy!
Proof that four strokes are over complicated
Dbailey
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Joined: Tue May 22, 2018 8:37 pm
Location: Portsmouth UK

Re: GT380 Carbs...

Post by Dbailey »

Hi guys.. sorry another question... what is the circlip position supposed to be on the main needle? I didn’t rebuild mine but would like to check they are in the correct std position?

Thanks
Dave Bailey
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Alan H
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Re: GT380 Carbs...

Post by Alan H »

Middle for diddle!
Proof that four strokes are over complicated
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