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GT550 idle problem
Posted: Sun Jun 26, 2011 12:30 pm
by dgloor
Quick question. I have a 1974 Suzuki GT550. It hasn't run since 1980 or 81. I had to rebuild the engine. I am not in any way a mechanic, but I can follow directions. I have it back together and it will start with choke. Seems like when it's warmed up it wants to die even on choke, but it won't run at all with the chock off. Actually it won't idle with the choke off, but it will if I keep giving it throttle.
Where should I try first. I went by the book on the pilot air screws. Have not tried ajusting these yet as i don't have enough hands to keep it running and try ajusting the carbs. It is not smoking too much. but enought to let me know it is getting oil.
Where do you think I should look first.
And thanks in advance for your concideration.
Re: GT550 idle problem
Posted: Sun Jun 26, 2011 12:37 pm
by bobotech
Did you completely refurbish the carbs? Tear them down completely and clean everything out and blow out all the passages with compressed air from an air compressor? Are all the needles and jets completely leaned out and free, not clogged at all? Did you clean out the choke/starter circuit?
I just redid a 75 GT550 that sat since 1981 and it now purrs like a kitten. However it doesn't like to idle with the choke off when it is nearly completely cold. I think that is just the nature of the beast with 2 strokers, after driving it a block or so or letting it warm up a minute or few, it then idles perfectly fine.
I did not have to buy any parts other than fuel/vent lines for the carbs. I was able to salvage everything including the fuel bowl gaskets. I'm just extremely picky and careful when I do carbs.
Re: GT550 idle problem
Posted: Sun Jun 26, 2011 12:40 pm
by bobotech
Just for more info, if it wants to run only when choked, then that means is usually running lean, make sure all of your fuel feeds/passages are completely freed up.
And the idle mixture screws should be backed out 1 1/4 turns from being seated gently.
Re: GT550 idle problem
Posted: Sun Jun 26, 2011 12:43 pm
by Coyote
Sounds like your pilot jets need a good going over. Make sure the jets don't have clogs in the little cross holes and make sure you can see through them from the end.
Remove the carbs as a unit. Pull off the bowls and remove the pilot jets.
Re: GT550 idle problem
Posted: Sun Jun 26, 2011 7:24 pm
by H2RICK
Pull off the bowls and remove the pilot jets.
Heck, why not go ALL the way and pull the main jets AND the needle jets and clean them, too.

Re: GT550 idle problem
Posted: Sun Jun 26, 2011 7:32 pm
by Cliff
Let's start from the begining. The engine hasn't run in 30 years so you rebuilt it. What did you do? Pistons and rings or a complete rebuild from the crank up? What's your compression?
Assuming that the engine is fine, what has been done to the carbs.? Disassembled and cleaned?
Intake and exhaust, stock or aftermarket pods and chambers?
The good news is that she will run and smoke!! That's a good thing!!
Keep us posted!
Cliff!
Re: GT550 idle problem
Posted: Mon Jun 27, 2011 7:55 am
by dgloor
Work that has been done... Tear down engine and replace the rings. It's a very low mileage bike. I knew the origonal owner that I bought it from in 1979. One of the cylinders had stuck from sitting. I took the cylinders to a machine shop and he said they were fine, just needed to be honed for the new rings. No oversizing needed.
I tore down the carbs and soaked in carb cleaner after removing anything rubber or plastic. Reassembled with a Keyster carb kits. Only using the o rings and bowl gaskets. Everything blown out with compressed air. I have the pilot air screws backed out 1.5 turns per the Clymer manual.
Re: GT550 idle problem
Posted: Thu Jun 30, 2011 10:20 pm
by BRP Tourer
Double check your pilot (low speed) jets. They have very small holes and are hard to get clean. I had to use a sewing needle to get the crust out of mine, carb cleaner wouldn't unblock them.
Re: GT550 idle problem
Posted: Fri Jul 01, 2011 5:56 am
by 650hardtail
once ya get em clean...a dose of seafoam wouldnt hurt
Re: GT550 idle problem
Posted: Sat Jul 09, 2011 11:52 am
by dgloor
Thanks guys!!!
The last thing I wanted to hear was that I had to remove the carbs again. I'm gonna wear out the boots just putting them on and taking them off. I did however. And I thought I had cleaned everything last year when I rebuilt them. (It never ran after the engine and carb rebuild last year. Grandbaby took priority and I put the project on hold.)
But after cleaning the pilot jets, it ran and idled ok. Then I replaced the plugs so I could get a fresh take on diagnosing the engine by plug color. Man this bike runs and sounds great. It didn't start this good 30 years ago. (thats how long it's been sitting.) Between this site and the Kaw triples web site (Suzuki forum) I have found all the info I needed. Just wanted to be sure to thank everyone who responded to my questions and everybody elses questions that I was able to research and not ask for myself.
I will keep up with the questions and if ever I can I will try to pass on what you all have helped me with. Thanks again!!!
Re: GT550 idle problem
Posted: Sat Jul 09, 2011 1:18 pm
by Scorch
Hey, thank you, for the follow up, that does help others. look forward to some pics, glad to hear you have it running better.
Re: GT550 idle problem
Posted: Sat Jul 09, 2011 2:30 pm
by jkevinlilly
As once popular series actor used to say,"I love it when a plan comes together".
Kevin