Hey!
I am new here. my name is Alex. I could take over the GT 380 of my dad. Love the triple sound, smell and looks.
Still riding a RD250C German edition. Just came back from a trip from Southampton - London - Dover and back to home, The Netherlands. Met some people with a Kettle.
I am bit younger but love the older two stroke bikes. RD is for sale and is still my first bike after 7 years riding and modifying.
So.
The GT my dad bought years ago has to fix a couple things.
Oil CIC lines (middle banjo failed).
Engine and tuning
Brake modification
Suspension modification
Past couple of months I have found some tune and modification files on the web. Like adding holes in front suspension tubes and different springs (race Tech?).
My dad say to me, please, don't tune the engine. Okay.
Goal is to make it kick and start ride ready.
Making longer tours.
Do you guys have suggestions?
I was thinking about adding a oil level switch in the oil tank like Yamaha did on later RD's. Maybe someone here has done it before.
Thanks advance!
Modications GT 380
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BAZ
- Posts: 3599
- Joined: Thu Jun 18, 2009 7:35 pm
- Location: Dudley west midlands
- Contact:
Re: Modications GT 380
Welcome to the forum, cheers Bluesmokebaz.
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Alan H
- Posts: 12118
- Joined: Fri Aug 05, 2011 6:38 am
- Location: Wombwell, Republic of South Yorkshire
Re: Modications GT 380
Welcome. Please remember that the GT Suzukis are 'Grand Touring' bikes, not sports machines. Rather than pay out good money to try and make them something they aren't, I'd suggest you bring it back to what it should be and enjoy it. 380scrun well and are fairly quick and handle well. What model is it? The very early ones with the front drum brake were underbraked, but Ferodo green linings cured that.
Baz (post above) builds Suzis for a living and has plenty of spares, plus there are lots of air cooled triples on here.
Regards the oil tank, it holds enough 2t oil for about a thousand miles, so if you do regular weekly or so checks, you'll not need a level switch. Nice bikes the 380s, although I do prefer my 550s as I like an 'electric leg' as a starter!
Baz (post above) builds Suzis for a living and has plenty of spares, plus there are lots of air cooled triples on here.
Regards the oil tank, it holds enough 2t oil for about a thousand miles, so if you do regular weekly or so checks, you'll not need a level switch. Nice bikes the 380s, although I do prefer my 550s as I like an 'electric leg' as a starter!
Proof that four strokes are over complicated
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BlueSmoked
- Posts: 5
- Joined: Sat Apr 15, 2023 9:14 pm
Re: Modications GT 380
Hey!
Yes agree, I don't want to modify the GT as a sporty bike. Otherwise I would go for a later RD or TZR or K1 etc.
Now I ride longer distance with my RD, it is for us to short bike or the way you sit on the bike.
The 370 is 20 kg heavier I saw and 550 another 40 kg (way longer).
So I think a GT 380 is a good startpunt for a two stroke traveler.
It has 6 speeds and front disc brake. If I remember right, 1975.
Thousands miles okay thats quit a distance. What is a suitable oil usage of these bikes 1liter : 50 km (25 ish miles)? Now it uses oil like a animal.
Yes agree, I don't want to modify the GT as a sporty bike. Otherwise I would go for a later RD or TZR or K1 etc.
Now I ride longer distance with my RD, it is for us to short bike or the way you sit on the bike.
The 370 is 20 kg heavier I saw and 550 another 40 kg (way longer).
So I think a GT 380 is a good startpunt for a two stroke traveler.
It has 6 speeds and front disc brake. If I remember right, 1975.
Thousands miles okay thats quit a distance. What is a suitable oil usage of these bikes 1liter : 50 km (25 ish miles)? Now it uses oil like a animal.
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arthur
- Posts: 128
- Joined: Wed Jun 17, 2020 8:55 pm
Re: Modications GT 380
Hi Alex and welcome ,
I hope you enjoy your 380 as Alan H says they are not a sporty bike but will happily keep up with modern A road traffic ( I have never ventured on to a Motorway) although I do find the front brake somewhat lacking and 6th gear is quite long and gradients may require a downshift or two, once you get used to it it's no problem ( I came to two strokes after years on a XJR1300 so it was a whole new experience
)
I hope you enjoy your 380 as Alan H says they are not a sporty bike but will happily keep up with modern A road traffic ( I have never ventured on to a Motorway) although I do find the front brake somewhat lacking and 6th gear is quite long and gradients may require a downshift or two, once you get used to it it's no problem ( I came to two strokes after years on a XJR1300 so it was a whole new experience
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Gr8uncleal
- Posts: 132
- Joined: Mon Jan 15, 2018 7:17 pm
Re: Modications GT 380
Welcome Alex and I hope you enjoyed the New Forest run, despite becoming detached from the main group! By the way, you probably rode past my front door on the run. 
I've got a GT550J to restore, but unfortunately there appear to be a load of Yamaha RDs and Enduros in front of it in the queue!
I've got a GT550J to restore, but unfortunately there appear to be a load of Yamaha RDs and Enduros in front of it in the queue!
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BlueSmoked
- Posts: 5
- Joined: Sat Apr 15, 2023 9:14 pm
Re: Modications GT 380
Thank you for welcome!
Ah I was thinking you Gr8uncleal , was riding with us. Yes we lost but at the end it is the price to ride a tuned RD350LC. And we rode 5 hours together. Very nice ride, love the landscape too. Great bikes you got to work on. Yes I think we all have that issue I got more ideas, hobby jobs, than time and funds
The GT, my dad bought +- 10 years ago before I got the RD. Ride it back then, but sitting still for couple of years. Last year I prepare the motor to get running. I found out that the banjo of the middle cylinder leaked over time. So that a couple of oil leaked in the crank and when kicking blocked the volume above the piston. So removed spark plug after some kicking and running on tow outer cylinders we go out lots of oil.
But the riding that around town it still quit heavy smoking. Like a Steam engine, see the video. Passing a police car I have to stopped on the side of the road after after siren and stop signal. Two young, my age, policemen and woman come out. They said, we can't saw your licence plate and check your registration! It was to much smoke, and hey your exhausts are wet of oil.
Yes how do you explain that. I said old motorcycle, old two-stroke. Had to explain that the motorcycle belongs to my father and did not have a registration certificate with me. They thought the engine had too much power for my A2 driver's license. But they couldn't read that online. I said look at Wikipedia, 38 hp. At the end I could leave and go to my girlfriend.
So yesterday started with this baby. Fist job get it running better. Have found a better oil lines from a shop here. Replace and need to vent them. Checking carburettors. Found out '72 engine and '72 24mm carbs. 4DH7 needles clip position 2 from under (from rich side). 22.5 pilot which is original, 90 left and right 92 middle main jets. 80 should be original. Maybe this should be put in for breaking in new engine, but never saw someone put in larger jets for breaking in. Only for compromising air leaks or wrong float height.
Checking the float heights, floats and valves look okay.
I met some young GT, T, Samurai rider on a two stroke meeting here in NL. He rode there with father and brother in law on a GT380 T350 and Samurai 350. We chat together about the bikes. We still working on the GT.
I heard from him that you can measure the float height "wet" with putting in fuel and measure height of fuel level through a pipe connected to the float tub. 4mm.
Wel we will see if 90 mains are to rich when tested on a chop shop spark plug test. First get the main adjustments and oil fixing. When burning the crankcase from oil, but in new BR8EIX spark plugs.
Question. Is it normal that the balls of the inlet side of the carburettor are removed (I think for cleaning)? I saw a couple of carbs on ebay that also the balls are removed. Would this does this affect the setup?
Alex
Ah I was thinking you Gr8uncleal , was riding with us. Yes we lost but at the end it is the price to ride a tuned RD350LC. And we rode 5 hours together. Very nice ride, love the landscape too. Great bikes you got to work on. Yes I think we all have that issue I got more ideas, hobby jobs, than time and funds
The GT, my dad bought +- 10 years ago before I got the RD. Ride it back then, but sitting still for couple of years. Last year I prepare the motor to get running. I found out that the banjo of the middle cylinder leaked over time. So that a couple of oil leaked in the crank and when kicking blocked the volume above the piston. So removed spark plug after some kicking and running on tow outer cylinders we go out lots of oil.
But the riding that around town it still quit heavy smoking. Like a Steam engine, see the video. Passing a police car I have to stopped on the side of the road after after siren and stop signal. Two young, my age, policemen and woman come out. They said, we can't saw your licence plate and check your registration! It was to much smoke, and hey your exhausts are wet of oil.
Yes how do you explain that. I said old motorcycle, old two-stroke. Had to explain that the motorcycle belongs to my father and did not have a registration certificate with me. They thought the engine had too much power for my A2 driver's license. But they couldn't read that online. I said look at Wikipedia, 38 hp. At the end I could leave and go to my girlfriend.
So yesterday started with this baby. Fist job get it running better. Have found a better oil lines from a shop here. Replace and need to vent them. Checking carburettors. Found out '72 engine and '72 24mm carbs. 4DH7 needles clip position 2 from under (from rich side). 22.5 pilot which is original, 90 left and right 92 middle main jets. 80 should be original. Maybe this should be put in for breaking in new engine, but never saw someone put in larger jets for breaking in. Only for compromising air leaks or wrong float height.
Checking the float heights, floats and valves look okay.
I met some young GT, T, Samurai rider on a two stroke meeting here in NL. He rode there with father and brother in law on a GT380 T350 and Samurai 350. We chat together about the bikes. We still working on the GT.
I heard from him that you can measure the float height "wet" with putting in fuel and measure height of fuel level through a pipe connected to the float tub. 4mm.
Wel we will see if 90 mains are to rich when tested on a chop shop spark plug test. First get the main adjustments and oil fixing. When burning the crankcase from oil, but in new BR8EIX spark plugs.
Question. Is it normal that the balls of the inlet side of the carburettor are removed (I think for cleaning)? I saw a couple of carbs on ebay that also the balls are removed. Would this does this affect the setup?
Alex
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BlueSmoked
- Posts: 5
- Joined: Sat Apr 15, 2023 9:14 pm
Re: Modications GT 380
Last week replaced the other oil lines and adjust the float height.
Today mounted the carbs back and have to ru engine on two outer cylinders to get out the oil of middle cylinder. After that engine runs, but left does not want to stationary run only when hit throttle.
So adjust screws on the cross method. And I notice that left is difficult to tune.
Tomorrow I would ride to a guy from my age who also has a GT380. There we can test and adjust float level on measuring fuel in a tube. Also the bike need some more parts, throttle cable, air filter etc.
He also had a Kawa Samurai, I know we have still some parts laying around. Found here crankcase 1 cylinder and 2 head alternator with points and some cables!
Today mounted the carbs back and have to ru engine on two outer cylinders to get out the oil of middle cylinder. After that engine runs, but left does not want to stationary run only when hit throttle.
So adjust screws on the cross method. And I notice that left is difficult to tune.
Tomorrow I would ride to a guy from my age who also has a GT380. There we can test and adjust float level on measuring fuel in a tube. Also the bike need some more parts, throttle cable, air filter etc.
He also had a Kawa Samurai, I know we have still some parts laying around. Found here crankcase 1 cylinder and 2 head alternator with points and some cables!