GT380 POOR RUNNING

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wardy
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Joined: Tue Jul 13, 2010 5:36 pm
Location: north lincolnshire

GT380 POOR RUNNING

Post by wardy »

Hi guys. I've been running up my GT380 tonight , with a view to putting it back on the road this year and have slightly puzzling fault.
When on choke all three cylinders fire well, but putting choke off, it's a bit "mushy" and won't tick over very well. I've noticed that the left downpipe is considerable cooler than the other two.
Am I correct in surmising that the left carb may have a blockage in the slow running circuit perhaps?
I would welcome a second opinion!
cheers
Andy
Andy;
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
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BAZ
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Re: GT380 POOR RUNNING

Post by BAZ »

Could be a blocked pilot Jet.
wardy
Posts: 1244
Joined: Tue Jul 13, 2010 5:36 pm
Location: north lincolnshire

Re: GT380 POOR RUNNING

Post by wardy »

Thanks Baz.. I'll have a look.
cheers
Andy
Andy;
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
willowden
Posts: 167
Joined: Thu Nov 16, 2017 3:10 pm

Re: GT380 POOR RUNNING

Post by willowden »

My GT380 was exactly the same & was driving me crazy , just couldn’t get to the bottom of it.
Turned out to be the crank seals. The choke was masking the extra air intake.
Hope it is just a carb issue.
wardy
Posts: 1244
Joined: Tue Jul 13, 2010 5:36 pm
Location: north lincolnshire

Re: GT380 POOR RUNNING

Post by wardy »

so do I!
took the float bowls off tonight to investigate and there wasn,t much fuel in any of them.. may be a float height issue as well.
determined to get to the bottom of it.
cheers for the input everyone.
Andy
Andy;
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
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slosher
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Joined: Fri Sep 23, 2011 6:55 pm
Location: Walsall,Black Country

Re: GT380 POOR RUNNING

Post by slosher »

Hi Andy
One cooler header pipe may be down to carb balance have you checked this :?: have got this on my 550 but mine ticks over well and responds well so i live with it, if that fails it appears to be slow running area (pilots) or air getting in hope it's not crank seals matey.
GT750L
GT550L
TL1000 97s
T140V
Loctite Trained Engineer :lol:(since having the Bonnie)
wardy
Posts: 1244
Joined: Tue Jul 13, 2010 5:36 pm
Location: north lincolnshire

Re: GT380 POOR RUNNING

Post by wardy »

Problem now sorted!
I've had the carbs off this weekend and on removing the float bowls I noticed there was not a lot of fuel in any of them. stripped out all the jets etc float valves etc and made sure all the drillings in the carb bodies were clear using carb cleaner and my air line. Then cleaned up all the crap in the bottom of the float bowls. On lifting the left hand pilot jet up to a light source, I could see that it was almost blocked compared to the other two. Cleaned it out in acetone. I;ve put everything back together, set the float height to where they should be , put everything back together and now it purrs like a kitten. Ticks over forever at 1100 rpm and I'm well chuffed. Really looking forward to riding the bike again this year. So... thanks everyone for their input, I'm releved it was not crank seals and can't wait for the better weather to come.
Andy
Andy;
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
User avatar
BAZ
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Joined: Thu Jun 18, 2009 7:35 pm
Location: Dudley west midlands
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Re: GT380 POOR RUNNING

Post by BAZ »

It would be a good idea to balance the carbs also this makes a big difference especially slow running..
wardy
Posts: 1244
Joined: Tue Jul 13, 2010 5:36 pm
Location: north lincolnshire

Re: GT380 POOR RUNNING

Post by wardy »

I'll check that as well Baz, thanks.
the left hand one does weigh more than the rest.
Andy;
1976 gt750A; 86 FZ750
1977gt380A
1982 z400j
1981 z650f.....1988 Sufolk punch 14"
"look;it's my bike; when you own it ,you can paint it any colour you like!"
(I once painted my Z650 PINK and had the pink panther logo on the tailpiece)
User avatar
BAZ
Posts: 3599
Joined: Thu Jun 18, 2009 7:35 pm
Location: Dudley west midlands
Contact:

Re: GT380 POOR RUNNING

Post by BAZ »

Best done with a flow meter.
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