Some progress on my GS550 but won't start

[hancadam]

I have finished the carb cleaning. I dipped them and installed new o-rings. I also installed new intake o-rings. After getting everything put back in place the bike will not start. It will only sputter a few seconds with starting fluid. I pulled the bolt from the bottom of one of the carbs bowl and gas runs out. I pulled on of the spark plugs, it is getting spark. One question though, the black T connectors in the middle of the carbs. What are they for, and where are they suppose to be connected. When I got the bike, nothing was connected to them. Also, I pulled the gas line off of the petcock and when I crank the motor gas does come out of the petcock. Any suggestions on why it will not start? The bike has 6,000 miles on it. It has only ran a few times in the past 20 years.

To me it seems to be getting gas and spark.

[Steve]

First of all, find the nearest trash can and pitch the starting fluid.
It is far too easy to do damage with that stuff in the honest effort to get the bike running.

The T connector between carb #2 and #3 is the fuel inlet. It should connect directly to the larger nipple on the petcock. The fact that you have gas in the bowls indicates that this might be correct. The T between #1 and #2, and the T between #3 and #4 are vents. If you have the stock airbox installed, there should be a hose attached that will run back, probably over the airbox to the battery area. If you are running individual "pod" air filters, remove the vent hoses from the Ts.

When you cleaned the carbs, did you do a bench sync? That will get the throttle plates close enough for the bike to run until you can do a proper vacuum sync. Your not starting issue now sounds like one of two things to me. Have you checked the valve adjustment? If the valves are too tight (and there is not much clearance to start with), the bike will be very hard to start. The second possibility is simply idle speed adjustment. Since you had the carbs apart, the idle might just be set too low for the enginen to run.


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[hancadam]

Thanks for the info. No I did not bench sync, I will look into do that. The bike started and ran before I tore the carbs apart. The guy who I got it from had it serviced by the local shop, but soon after started to leak fuel and was parked again. It seems like the gas is not getting into the cylinders. If the bowls are full of gas, what would stop it from getting into the cylinders. Also, how will starting fluid hurt my bike? I am worried now. One possible issue is, I did not remove the top mixture screw when rebuilding the carbs. I am talking about the one you have to drill the aluminum block out of to get to. Could this be the issue? Thanks for all help!!!!

[Nessism]

Sounds like you learned lesson number one about cleaning carbs - take them 100% apart. The mixture screw had a large influence on idle mixture and if the orifice is blocked you won't get the bike to run right. Also, the pilot circuit is very critical to clean because it has very small orifices. The pilot circuit is often overlooked by people not wanting to get too deep into the cleaning process. Sorry to say but you should take the carbs back off and finish the job you started.

Hope this info helps.

[hancadam]

You are correct. I am going to do it all over again. Its all a learing process. Also I am now reading in my manuel the pilot air screw should be screwed all the way in, then backed out 2 turns. I did not back mine out. Would this also cause the bike not to start?

Should I just order 4 new rebuild kits while I am at it?


Thanks again!!!

[relic-rider]

Yes if your mixture screws are all the way in it won't idle at all. Also, when you take off the carbs again, remember to clean out holes in the end of the thin brass tubes. These are for the choke circuit. also make sure the corresponding hole at the bottom of the float bowl covers is open on each carb. These feed the small pocket in the float bowl cover for the choke tubes.

[MelodicMetalGod]

You are correct. I am going to do it all over again. Its all a learing process. Also I am now reading in my manuel the pilot air screw should be screwed all the way in, then backed out 2 turns. I did not back mine out. Would this also cause the bike not to start?

Should I just order 4 new rebuild kits while I am at it?


Thanks again!!!

Question: What is the year and specific model of your bike?

Regarding the pilot screws (aka "air screws", aka "needle screws", aka "air mix screws"): As I've recently experienced first hand, these screws are VERY susceptible to "rounding" off the slots, particularly if they are grounded out too tightly. 2 of the 4 on my carbs were grounded out and stripped enough that I'm having to drill them out. If these are all the way in, then the bike will likely not start.

FYI: In most dialogue on the pilot screws, I've been recommended that they be turned out 3 to 4.5 turns. Keep in mind also that the pilot screws are considered to be "pre-set" or a "factory setting" that us mere mortals were not intended to mess with. However, it also seems that the factory setting runs a bit lean, which is probably why everyone digs into them.

[hancadam]

Question: What is the year and specific model of your bike?

Regarding the pilot screws (aka "air screws", aka "needle screws", aka "air mix screws"): As I've recently experienced first hand, these screws are VERY susceptible to "rounding" off the slots, particularly if they are grounded out too tightly. 2 of the 4 on my carbs were grounded out and stripped enough that I'm having to drill them out. If these are all the way in, then the bike will likely not start.

FYI: In most dialogue on the pilot screws, I've been recommended that they be turned out 3 to 4.5 turns. Keep in mind also that the pilot screws are considered to be "pre-set" or a "factory setting" that us mere mortals were not intended to mess with. However, it also seems that the factory setting runs a bit lean, which is probably why everyone digs into them.

My bike is a 1980 model. To make sure we are talking about the same screw: I am talking about the one right next to the main jet. I am going to buy the rebuild kits because I really screwed these up. My book also states it will decrease carb performance if even slightly damaged. Thanks again for the help. Is there anything else I should be aware of that is often overlooked?

[MelodicMetalGod]

This pic illustrates the pilot circuit for my carbs (Mikuni BSW30SS) and you should be able to correctly identify what parts you're referring to. I was referring to the pilot screws (top left in the image). It sounds like you are probably referring to the pilot jets (since you indicated they are right next to the main jets). Hope this helps.

PS: Since you've got 1980 model, I'm pretty sure you've got a different set of carbs than I do, but the principles should still be the same.

[hancadam]

This is the jet I am talking about(the one next to the pencil):

http://www.thegsresources.com/images/carbs/044_Pilot%20Jet%20with%20Plug%20removed.jpg

Is there a setting for it? Does it need to be backed out 2 turns? I am confused now. Thanks, Adam.

[relic-rider]

No! Both of those jets need to be screwed in all the way. They are fixed jets and do not adjust at all. The mixture screw we are talking about is on the other side.


http://www.thegsresources.com/images/carbs/026_Air%20screw%20removed.jpg

In the pic it is called an air screw, but it actually adjusts the amount of air/fuel mix for idle.

[hancadam]

I haven't touched them. Any ideas on why the bike is not at least somewhat running? The bike will not start at all. I soaked each carb for 24 hours. The air mixture screws are the only ones I did not remove. The bowls are filling full of gas, and the spark plugs are getting spark. It seems the gas is not getting into the cylinders. I will crank and crank, but the plugs never get wet. This is my first 4 cylinder bike which is a whole new beast to me. I have only had 1 cylinder bikes until now. All the help is greatly appreciated.

[relic-rider]

Sorry to say but Off with those carbs! Go through the carbs step by step as illustrated on the link on the homepage here. Make sure you check steps 75 -78 for the choke operation and pay attention to the mixture screw illustration(they are referred to as air screw in the pics). Those need to come out now. There is a small o-ring under the screw that probably swelled up after you soaked the carbs the first time. And check and set the float height.

[hancadam]

Will do. I don't mind the work, I kinda enjoy it. I am just getting impatient and want to ride it. I will post some pics of it later. I have painted the tank, replaced the shocks, new bars, painted the frame, new tailight, new side panels, and painted the plastic rear end. It is looking pretty good. Thanks again for all the suggestions. I am getting mixed answers on the mixture screws though. So 3 to 4.5 turns is recommended as a starting point? Thanks, Adam

[mbautsch]

I've just recently been through what you are going through. I have the 81 550t and I can now take the carbs apart in my sleep. When you take them apart to clean them be sure to blow them out very well with an air compressor, mine never worked properly until I did this. I soaked them in carb cleaner for about 30 minutes and them hit them with the air compressor through all of the openings.

I also learned that a bad petcock will dump fuel down the vacuum hose directly into the #2 cylinder flooding that cylinder, don't overlook anything. I had no idea my petcock was bad, making it look like one of my carbs was not working properly.

As for the mixture screw, I am still trying to figure out the best way to adjust them.

Hope this helps.

Mike