GT380 Carbs...

Post your problems / information on the smaller GT Models here
Dbailey
Posts: 80
Joined: Tue May 22, 2018 8:37 pm
Location: Portsmouth UK

Re: GT380 Carbs...

Post by Dbailey »

Thanks Alan....

Dave Bailey
JonnyAstro
Posts: 12
Joined: Sat Apr 06, 2019 7:26 pm

Re: GT380 Carbs...

Post by JonnyAstro »

HI All,
I have a '74 GT380M which was extensively restored before I got it, and i've addressed most of the leftover issues now. However, I am convinced that its remaining poor throttle response off idle is due to the pilot jet bypass issues described by previous posts here. Once you get the throttle open a bit it all works well, so the mains are surely OK...
So I'm going in with carb cleaner and tiny jet cleaner rods as suggested above.
Any advice on the best way to get the carbs off? It all looks vey cramped! Presume remove the airbox first?
Jon
barney01
Posts: 3118
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: GT380 Carbs...

Post by barney01 »

Hi
Yes the carbs are suspended between the cylinder rubbers and the airbox. Ive given you a link to the carb manual to help.
http://www.3cyl.com/mraxl/gt/manuals/su ... /cover.htm
NO SMOKE .......NO POKE
JonnyAstro
Posts: 12
Joined: Sat Apr 06, 2019 7:26 pm

Re: GT380 Carbs...

Post by JonnyAstro »

Had the carbs off and found that the middle one was WAY out of synch with the user two. There was about 5mm of free play in the linkage so it was always going to be an issue...
Rebuilt all carbs using Keyster kits, balance/synch and it's all MUCH better! Just need to finish running in - up to 350 miles now so I let it go to 5K a couple of times, and it starting to sound nice and "edgy" and feel really good.
Aah, two strokes - doncha love 'em?
Jonny
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Alan H
Posts: 12104
Joined: Fri Aug 05, 2011 6:38 am
Location: Wombwell, Republic of South Yorkshire

Re: GT380 Carbs...

Post by Alan H »

JonnyAstro wrote: Rebuilt all carbs using Keyster kits, balance/synch and it's all MUCH better!
It would have been even better if you'd used genuine Mikuni.
Proof that four strokes are over complicated
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Gary66
Posts: 710
Joined: Sun Jan 05, 2014 10:53 am

Re: GT380 Carbs...

Post by Gary66 »

I got my carb kits from Cruzin Image in Japan, no complaints at all and have had many other bits including pistons, great service and products!
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