Gt550 runs with choke

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JessC
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Suzuki 2-Strokes: GT550
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Gt550 runs with choke

Post by JessC »

Hi,
I have a 1975 GT550 that starts up fairly easy but likes to run with choke on mostly. I got this bike after siting God knows how many years.The guy I got it from filled cylinders with a lot of oil.
so after I have gotten it hot the smoke is not bad. could it be I set floats wrong or something I missed when cleaning the carbs? How do I set float level? I had to replace a pilot jet "had a heck of a time getting old one out" Dealer ordered the jet
Thanks
Jess
karl pa
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Re: Gt550 runs with choke

Post by karl pa »

Most times when they only want to run on choke, it is clogged pilot circuit in carbs. There are so many small passage ways it is hard to get totally cleared, I use carb cleaner and air hose to blow through passages to see if there open, even so I don't always get them cleared, sometimes it takes me several tries.
The way I set float level, holding carb upside down, the float arm tang just touches the needle valve plunger when the float arm is parallel to the carb body. Some might not agree but that is how Suzuki dealer showed me.
The most accurate way is to screw adapter in bowl drain with hose up the side of carb and fill bowls, level in hose will show the level in carb.
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe
JessC
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Posts: 20
Joined: Mon Oct 01, 2018 6:32 pm
Country: USA
Suzuki 2-Strokes: GT550
Location: California

Re: Gt550 runs with choke

Post by JessC »

Can the left crank seal be replaced without splitting cases?
GTandcbr
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Re: Gt550 runs with choke

Post by GTandcbr »

As Karl says almost certainly clogged pilot jet circuit. You can replace the jet but the pilot jet circuit and also possibly the bypass too may be dirty and restricts fuel flow at low throttle position. The proper way to get them clean is several runs through an ultrasonic cleaner as it's virtually impossible to access the internal passages. The pilot jet bypass feeds fuel/air into the mouth of the carb through a little passage with a metered non removable jet.
I prefer to set float height using the below very cheap gadget.
https://www.z1enterprises.com/fuel-leve ... uzuki.html" onclick="window.open(this.href);return false;
98 carb Blackbird and GT550j
karl pa
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Re: Gt550 runs with choke

Post by karl pa »

JessC wrote:Can the left crank seal be replaced without splitting cases?
I know the right seal can not, but I believe the left one can.
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe
JessC
On the street
Posts: 20
Joined: Mon Oct 01, 2018 6:32 pm
Country: USA
Suzuki 2-Strokes: GT550
Location: California

Re: Gt550 runs with choke

Post by JessC »

should the petcock diaphragm hold a vacuum?. I lined up vent hole with plate vent hole on petcock I have a feeling it should hold a vacuum right?
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jabcb
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Re: Gt550 runs with choke

Post by jabcb »

JessC wrote:Can the left crank seal be replaced without splitting cases?
The left crank seal has a lip on the OD that fits into a groove in the crankcase. So you have to split the case to replace it.
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karl pa
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Re: Gt550 runs with choke

Post by karl pa »

jabcb is right.
Is there a problem with the left seal, unfortunately if one seal is bad they all seem to be.
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe
JessC
On the street
Posts: 20
Joined: Mon Oct 01, 2018 6:32 pm
Country: USA
Suzuki 2-Strokes: GT550
Location: California

Re: Gt550 runs with choke

Post by JessC »

I cleaned pilot jets and mains..left cylinder (i guess seal not leaking) was running but center and right were not except when I had choke on or covered up inlet of carb. they would fire.. checked timing on all 3 cylinder with a timing light and all were dead on. pilot get I used a tiny strand of wire thru each jet
Back to taking carbs off and going thru them again . any ides on what to try next if this does not work?
karl pa
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Re: Gt550 runs with choke

Post by karl pa »

JessC wrote:pilot get I used a tiny strand of wire thru each jet
It's not just the jet, it is the passage ways the jet and idle mixture screw is in, as was said ultrasonic cleaner is best option if you have access to one.It sounds like the pilot circuit is still clogged.
The timing marks are not always on, you should set timing with dial gauge. I use dial gauge and set piston height, then check where the timing marks are, and set it to that point with timing light.
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe
JessC
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Joined: Mon Oct 01, 2018 6:32 pm
Country: USA
Suzuki 2-Strokes: GT550
Location: California

Re: Gt550 runs with choke

Post by JessC »

I ordered a small ultra sonic cleaner from E-b@y. what should I use for the cleaner once I get it?
GTandcbr
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Suzuki 2-Strokes: suzuki gt 550j
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Re: Gt550 runs with choke

Post by GTandcbr »

IMHO it is best to use the dedicated ultrasonic cleaner carb fluid. Anything else will attack the alloy the carbs are made of. Easily purchased off ebay.
You won't regret buying the cleaner the results will amaze you. I put my carbs through the cycle every time they are off.
98 carb Blackbird and GT550j
JessC
On the street
Posts: 20
Joined: Mon Oct 01, 2018 6:32 pm
Country: USA
Suzuki 2-Strokes: GT550
Location: California

Re: Gt550 runs with choke

Post by JessC »

UPDATE....I took all 3 carb. bodies into work and got the lab to ultrasonic clean them. no difference I get bike to about 2 thousand rpm and it sounds like 2 other cylinders are trying to fire. I have sprayed carb. cleaner around cylinders and intake boots nothing at all changes. very little smoke out of the pipes. Petcock holds a vacuum.
I lost on what to try next.. has me stumped!!

Jess
GTandcbr
Yeah Man, the Interstate
Posts: 590
Joined: Tue Mar 10, 2015 12:35 pm
Country: WALES
Suzuki 2-Strokes: suzuki gt 550j
Location: Wales

Re: Gt550 runs with choke

Post by GTandcbr »

Okay it's time to take a step back. It now seems likely it's not a pilot circuit problem. We need to make sure that the float level is being set correctly because it may be that there is not enough or too much fuel in the float bowls. Run the engine as you have done then remove the plugs immediately. Are they wet?
What height have you set the floats to? Early separate carbs have a different float level.
One question. Bike starts on choke does it run after choke is closed off before you touch the throttle?
98 carb Blackbird and GT550j
JessC
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Posts: 20
Joined: Mon Oct 01, 2018 6:32 pm
Country: USA
Suzuki 2-Strokes: GT550
Location: California

Re: Gt550 runs with choke

Post by JessC »

I have just gotten the visual float tube from z1 to view level will do that next float bowls seen to have plenty of fuel.
Bike like the choke when starting up,it like throttle to keep running..seem to run better when I put hand over carb.
plugs are new so no color.. bike sounds healthy with choke on...could I try spraying carb cleaner thru opening for needle jet while running?
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