750GT Amal Carb settings

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thessler3
Mariana
Posts: 35
Joined: Tue Jul 30, 2013 1:57 pm

750GT Amal Carb settings

Post by thessler3 » Sun Aug 04, 2013 2:01 pm

When I started restoring my 73 750GT - US model, I noted the needles were set on the top slot. My little owners manual said slot two, so I moved them when I cleaned the carbs. The owners manual also said it should have 190 main jets, but the carbs have 200 main jets in them. My bike has a low speed surge problem on light throttle between 3000 & 4000 RPM with light load. Seems rich, not lean, when run on 100LL av gas, which has no ethanol. Others that have used this gas says it is the way to go here in NJ where you cannot buy ethanol free gas. I recently installed a Dyna ignition and the bike runs better, but still the surge. I went on the Amal web site and they say the needles should be on slot one (the top slot). Can anyone share with me their settings and jet sizes for an early 750GT? Also, can anyone tell me the correct slide cutaway - I cannot read mine. Thanks for the help.

Note that I am going to try needle position # 1 in a couple of days - just to see if there is any improvement.

One more question - anyone know what the "diffuser" is on these Amal carbs?

darmahdave
Cucciolo - the Lil Pup
Posts: 1
Joined: Thu Dec 27, 2007 2:18 am

Re: 750GT Amal Carb settings

Post by darmahdave » Tue Aug 06, 2013 5:35 am

what parts have you replaced in the carbs?

thessler3
Mariana
Posts: 35
Joined: Tue Jul 30, 2013 1:57 pm

Re: 750GT Amal Carb settings

Post by thessler3 » Thu Aug 08, 2013 3:22 am

None yet, just a thorough cleaning. I have needles, needle jets, strainers, gaskets and Viton tipped float valves on their way. I also am installing new Barnett cables. My Amal carbs have not had a lot of use. The bike had Mikuni carbs on it for many years. I have put the Amals back on to make it more original. I am not using ethanol gas yet for fear of my fiberglass tank, but was told to replace the floats too if I intend to use ethanol gas. I can get all these parts from British Cycle Supply here in New Jersey.

thessler3
Mariana
Posts: 35
Joined: Tue Jul 30, 2013 1:57 pm

Re: 750GT Amal Carb settings

Post by thessler3 » Mon Aug 19, 2013 4:15 pm

I had to put some 10% ethanol fuel in the other day to get home when I ran out of av gas. The bike actually ran better with the pump gas, but I drained it out when I arrived home. I did not want to chance any ethanol in the fiberglass tank for any length of time.

The bike is running pretty good with the AMAls with 200 main jets and new needles set in the top slot. No more surging. New Barnett cables work good with the AMALS. I also suggest Viton tipped brass float valves. Better than the stock nylon ones.

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