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PostPosted: Sat Sep 07, 2019 3:59 pm 
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On the street

Joined: Sat Apr 15, 2017 2:20 pm
Posts: 11
Location: Bay Area
Country: united states
Bikes owned: 1972 GT750
I'm new to GT550's and currently have one that I'm trying to get running. I took down the carbs and have cleaned them throughly through an ultrasonic cleaner. I reassembled the carbs and I'm trying to set the float height and pilot air adjusting screw. These are the values I found and just want to see if they are correct.

Pilot Air adjusting screw ............. 1-1/4 turns back from seated
Lost height ................................. 24.25 mm

Also I noticed that the middle carb looks a little different than the #1 and #3 carb. Is there a difference in the jets or are they the same in all three carbs?

Any help would be appreciated and thanks in advance


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1972 GT750 Lavender
1972 GT550 Aztec gold
1969 Honda CB750 Blue Green
1969 Honda CB750 Ruby Red
1969 Honda CB750 x4 projects
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PostPosted: Sat Sep 07, 2019 11:55 pm 
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To the on ramp

Joined: Tue Mar 10, 2015 12:35 pm
Posts: 497
Location: Wales
Country: WALES
Bikes owned: suzuki gt 550j
Your carb settings are correct and the float height is crucial and not to be changed however the pilot air screw is adjustable so 1 1/4 turns is a starting point. The pilot air screw is adjusted according to many things including altitude and climate. All three carbs are different so they have a letter L C or R just under the choke plunger. I have attached a couple of links to help.
http://www.3cyl.com/mraxl/gt/manuals/gt ... ntents.htm" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
http://www.3cyl.com/mraxl/gt/manuals/su ... /cover.htm" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
Also look here to understand some of the holes in the carb
viewtopic.php?f=2&t=11705&p=155179&hilit=Carb+Holes#p155179

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98 carb Blackbird and GT550j


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PostPosted: Sun Sep 08, 2019 7:11 am 
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Moto GP
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Joined: Mon Dec 13, 2010 4:32 pm
Posts: 3477
Location: southwestern Pennsylvania
Country: USA
Bikes owned: 69 T350 thru 75 GT750
Sweet little collection you have there.


Suzuki used 5 slightly different versions of cable operated carbs on the 72/73 GT550. Later GT550s have a different carb setup.

A number is stamped along with the letter (“L”, “M” or “R”) near the choke plunger. That number is the second part of the carb parts number & it tells you which version of carbs you have.
1st version # is 34011 followed by a letter. 5th version # is 34015 followed by a letter.

Your middle carb might be a different version than the other two carbs. Suzuki might have done that at the factory or some PO might have replaced some of the carbs.

Suzuki issued a service bulletin that covers the model-year variations in carb jetting. (The GT550 middle carb has a slightly different main jet.)
See Specification-6: http://www.ozebook.com/compendium/techbuls/SerBulletin%20Specifications%206-9.pdf

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BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 73 project
T350 69, 71 & 72 project
T250 72
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE


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PostPosted: Sun Sep 08, 2019 3:54 pm 
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On the street

Joined: Sat Apr 15, 2017 2:20 pm
Posts: 11
Location: Bay Area
Country: united states
Bikes owned: 1972 GT750
Thanks guys for the great info. Very helpful. I'm used to working on Honda CB750's and these two-strokes are a whole different creature. I had a great deal on this particular 1972 GT550 and it only had 3,000 miles on the engine so I thought I would try my hand at a GT550.

I just had a few follow up questions regarding the carb reassembly. When I cleaned the carb internals (main jets, pilot jets, needle valve and seat), I forgot to note which internals went to which carb. Are the pilot and main jets the same between the 3 carbs?

_________________
1972 GT750 Lavender
1972 GT550 Aztec gold
1969 Honda CB750 Blue Green
1969 Honda CB750 Ruby Red
1969 Honda CB750 x4 projects


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PostPosted: Sun Sep 08, 2019 11:53 pm 
Online
To the on ramp

Joined: Tue Mar 10, 2015 12:35 pm
Posts: 497
Location: Wales
Country: WALES
Bikes owned: suzuki gt 550j
Here you go
http://www.3cyl.com/specs/suzi3carb.jpg" onclick="window.open(this.href);return false;
And another useful link in case you don't have it
https://www.oldjapanesebikes.com/mraxl_ ... /index.php

_________________
98 carb Blackbird and GT550j


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