Running issue GT380

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Dbailey
Posts: 78
Joined: Tue May 22, 2018 8:37 pm
Location: Portsmouth UK

Running issue GT380

Postby Dbailey » Sat Mar 21, 2020 8:10 pm

So bike was running ok but not particularly well at higher revs. I took the plunge and bought a complete set of carb parts including needles, pilot and main jets, float vales and seats and lastly air screws and o rings. All of the parts are genuine original parts not pattern. The bike won’t idle very well and flat when you open the throttle but runs ok above 3 1/2 to 4K. If I completely close the air screws the bike will idle and pickup although not perfectly but way better. The only thing I changed in terms of baseline setup was moving the circlip to the middle position down one from previous on the needle valve. I did this to give more fuel at higher revs. I didn’t think needle valve position affected idle. I have had a check and can’t see any places where there are any air leaks...


Any thoughts guys? I’d like to get some opinions before I start ripping stuff apart again,

Thanks
Dave Bailey

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Alan H
Posts: 10216
Joined: Fri Aug 05, 2011 6:38 am
Location: Wombwell, Republic of South Yorkshire

Re: Running issue GT380

Postby Alan H » Sun Mar 22, 2020 7:20 am

Take the carbs off and send them to Baz.
He's an egg spurt.
Proof that four strokes are over complicated

barney01
Posts: 2673
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Running issue GT380

Postby barney01 » Sun Mar 22, 2020 8:35 am

Idle problems are almost certainly caused by blocked pilot jet circuit or pilot jet bypass as these have a large effect on idle and up to 1/4 throttle opening. They are very difficult to access and it takes but a tiny foreign body to block it up.
If you have access to an ultrasonic cleaner thats ideal. New jets will not solve the problem if the passages are dirty or blocked.
If you have'nt fitted an in line filter do so, otherwise small particles of rust from the tank into the carbs.
Lastly just check that your choke pistons are returning as they should as if they stick open it will cause it to overfuel at idle and effect high revs too.
NO SMOKE .......NO POKE

Dbailey
Posts: 78
Joined: Tue May 22, 2018 8:37 pm
Location: Portsmouth UK

Re: Running issue GT380

Postby Dbailey » Sun Mar 22, 2020 9:07 am

Thanks guys...

Dave Bailey

Dbailey
Posts: 78
Joined: Tue May 22, 2018 8:37 pm
Location: Portsmouth UK

Re: Running issue GT380

Postby Dbailey » Sun Mar 22, 2020 9:14 am

Sorry trying to look up Gaz (savs) to pm him for a strip and clean price...

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PaulD738
Posts: 3325
Joined: Thu Sep 25, 2014 6:57 pm
Location: Warrington Cheshire

Re: Running issue GT380

Postby PaulD738 » Sun Mar 22, 2020 9:16 am

Dbailey wrote:Sorry trying to look up Gaz (savs) to pm him for a strip and clean price...

Hi Dave, it’s BAZ your looking for just search in the members list 8-)
There rubbish them Jap bikes lad they won't last five minutes! you want to get yourself a nice Royal Enfield!
A quote from my old dad 8-)

I started out with nothing and I’ve got most of it left!

Dbailey
Posts: 78
Joined: Tue May 22, 2018 8:37 pm
Location: Portsmouth UK

Re: Running issue GT380

Postby Dbailey » Sun Mar 22, 2020 9:49 am

Thanks everyone...

Dave Bailey

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2strokejohnny
Posts: 1178
Joined: Sun Nov 08, 2009 7:20 am
Location: Bed/Cambs border

Re: Running issue GT380

Postby 2strokejohnny » Tue Mar 24, 2020 5:31 pm

gt750 one,suppose this will fit other gt models ?
Attachments
IMG_20200324_172012795.jpg
Suzuki GT750B
Suzuki GT380M
Triumph T100 Unit Bonny

Dbailey
Posts: 78
Joined: Tue May 22, 2018 8:37 pm
Location: Portsmouth UK

Re: Running issue GT380

Postby Dbailey » Sun Mar 29, 2020 8:03 pm

Thanks everyone ... update Barry is about to do his magic... thanks for the recommendation...

Dave Bailey


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