GT380A 2 stroke oil consumption

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gingerchunkyboy
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Joined: Mon Sep 20, 2021 7:39 pm

GT380A 2 stroke oil consumption

Post by gingerchunkyboy »

Hello all My name is Paul O'Brien i live in Aylesbury i'm new to the forum but have owned a GT380Afor about 14 years now . I also own a Yamaha RD250LC . Over the years i have noticed the GT380 uses more 2 stroke oil than the LC . Now my son has grown up we now ride the bikes together and after long rides it is realy noticeable as to how much more oil the GT380 gets through so much so i have measured the 2 bikes consumption ratios . The Gt uses 1litre off 2 stroke oil to every 25 liters of petrol where as the LC is using 1 liter of 2 stroke oil to 40 litres of petrol . The oil pump is set to its minimum . I was wondering does 25 to 1 sound about right and if not is there any way to overhaul the pump .
stupot
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Location: under bridge J22 M60

Re: GT380A 2 stroke oil consumption

Post by stupot »

50 to 1 is the optimum mixture , I know this because it was what we put into my nephews go cart a few years ago , It had to be precise as if it was slightly out iether way the cart would be a tad slower we re talking hundreths of a second.
everyones a winner
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malky
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Joined: Sat Dec 19, 2009 3:25 pm
Location: swansea south wales

Re: GT380A 2 stroke oil consumption

Post by malky »

My old GT380A used to drink two stroke oil - after each run I had to clean the rear of the bike as it used to be covered in oil including the spokes on their leading edges - looking back I think the pump arm had been fitted 180 degrees out as I believe its quite easily done if its removed
teazer
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Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: GT380A 2 stroke oil consumption

Post by teazer »

Oil pumps shouldn't wear out but anything is possible. The equivalent of 25:1 sounds much higher than I would have expected, though it won't hurt much except the environment and your wallet.
Stupot's post was very interesting. We found that more oil always makes more power on almost any two stroke with conventional oil. Many synthetics specify 50:1 for MX motors, but that's with pre-mix. Pump should be way more like a Yorkshire man or a Scotsman.

Could it perhaps be adjusted wrongly or is it possible to adjust it to run with less oil?

I was wondering if is it possible that it has an earlier "330" oil pump which had to be adjusted a little differently, but that is unlikely. My guess would be that the check valves are leaking allowing oil to drain out faster than stock.

If it bugs you enough, wait until the rainy season (summer) is over and remove the pump and oil lines over winter and check it all.

http://pinkpossum.com/GT750/Oilpump.htm is about GT750 oil pumps, but the design is the similar.
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: GT380A 2 stroke oil consumption

Post by Alan H »

teazer wrote: Tue Sep 21, 2021 3:27 pm Pump should be way more like a Yorkshire man or a Scotsman.
Oi, am watchin' yerno!!! :roll:
But mekyermindupwich. :shock:

Hippo & 550 do about 750ml/2t oil to 1000 miles depending on riding 'style'.
Proof that four strokes are over complicated
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stevewharton
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Location: Grimsby, Lincolnshire.

Re: GT380A 2 stroke oil consumption

Post by stevewharton »

teazer wrote: Tue Sep 21, 2021 3:27 pm Pump should be way more like a Yorkshireman.
:lol: :lol: :lol: :lol: :lol:
Look, my paintwork hasn't got "Fish scales" :x they're "Dragon scales" right!!! However, after some thought, I will accept "Black Marlin" or "Swordfish", but definitely not "Haddock" or "Cod".
wardy
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Joined: Tue Jul 13, 2010 5:36 pm
Location: north lincolnshire

Re: GT380A 2 stroke oil consumption

Post by wardy »

I had this issue a while back on my 380 too. I've owned the bike since 2001 , but some previous owner had taken the pump apart and put the operating arm back on 180 degrees out, so it was pumping at maximun all the time. easily fixed though; just take off the top of the pump and remove the operating arm (the one the cable attached to) and then rotate the shaft it goes onto in the head of the pump through 180 degrees and put the arm back on.. job done!
an excellent intruction on this is a site called "Yans 380" in which a guy rebuilds a 380j .He comes across the same problem and shows you how to fix it like i've just described. You'll have to search for it on his site, but it is there.
Since i've done mine, the bike runs very cleanly and the consumption is just as low as on my gt750, with minimal cleaning up to do after a ride.. this seems to come up so often; I wonder if everyone used to mess around with their oil pumps back in the day!
Hope this helps!
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)
wardy
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Location: north lincolnshire

Re: GT380A 2 stroke oil consumption

Post by wardy »

[attachjust some pics of my bike that I've owned since 2001; used to be my daily rider , and got into a right old state... rust everywhere!ment=1]mondeo 020.JPG[/attachment]
mondeo 020.JPG
Attachments
my bike; taken last year
my bike; taken last year
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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