?82 GS750T-starting trouble

[Guest]

Well, I pulled my carbs (for the millionth time time) and I saw that the idle adjuster was screwed in all the way Leaving the carb valves open. This caused some of my starting issues. I also re-cleaned the little float bowl holes and the small pipes that fit down into them. I screwed the fuel mix screw out about 2.5 turns out as a start.
I was then able to choke it to start. But it only idles with half choke. And it also doesn?t hold at a constant rpm, it races sup and back a little. I?ve cleaned the carbs more than once and have recently replaced the needle/seat, jets, o-rings (thanks GSResources).
Other than check for air leaks and re-check the jets, are there any other suggestions? Thanks for any help.

 

[Rich82GS750TZ]

Sounds like an air leak. Do one thing at a time and by process of elimination, you should get there. While it’s running, spray wd40 or something around the intake rubbers between carbs and head, between airbox and carbs, between air filter box and airbox. Note if an RPM change at any specific points. If you’re getting the carbs In and out easily I’m thinking your boots are supple enough, but maybe there’s a tear or crack through somewhere?

 

[Guest]

Sprayed starting fluid at all those potential gaps. No change in rpm. I checked the fuel mix screws again. Screwed them all out at 2 turns.
I Well, looks like maybe I Just need a new air filter! I had a gaping hole in the air filter. I suppose that allowed too much air. I wrapped some weather stripping around that big hole in the filter. Low and behold, she started! I tuned the idle screw while reducing the choke. Now, at least for now, she seems to be running real good. Best in years! Fingers crossed, she will start up and run again tomorrow... Hopefully, now I can do the cosmetic work. Thanks!!

 

[Rob S.]

Welcome to the site. Put your year and model in your signature.

 

[Guest]

I’ve added it. Thanks.
Just to quench my curiosity, I went out later this afternoon and started, well attempted to start her up... So temperamental! It started up, but wouldn’t idle. Then it did for a bit and then died. After that I couldn’t get it started again before the battery died. And after buttoning up everything, it’s not so quick to open up again and put it on charge.
Guess I will try again tomorrow. So frustrating. Not feeling like I can trust taking this bike anywhere that I have to leave it off for a long time....or even a short time.

 

[Rich82GS750TZ]

I keep these attached all the time, but it’s especially helpful while troubleshooting running or charging issues because you find yourself often running down the battery, to permanently install leads on to the battery posts that will connect to your battery charger/tender with some type of quick connector. You can make them long enough that they can hang down below the side cover for connection then be tucked away when not in use. No more removing seat, tank, and air filter box just to get to the battery. Took me years to figure out something so simple. Now if I’m gonna leave the bike sit for a while I just plug it in.

Back to your running issues. Have you verified that your valve clearances are in spec?

In case you don’t have manuals. Go to BikeCliffs website and download the service manual. It’s close enough for most stuff.
http://zeus.mtsac.edu/~cliff/storage/gs/GS750_16valve.pdf

I also have a factory supplement which is very helpful for a lot of things specific to our model.

 

[MArider]

I?ve added it. Thanks.
Just to quench my curiosity, I went out later this afternoon and started, well attempted to start her up... So temperamental! It started up, but wouldn?t idle. Then it did for a bit and then died. After that I couldn?t get it started again before the battery died. And after buttoning up everything, it?s not so quick to open up again and put it on charge.
Guess I will try again tomorrow. So frustrating. Not feeling like I can trust taking this bike anywhere that I have to leave it off for a long time....or even a short time.

Is the battery good? hate to start with a silly question but I have had more than a few bikes that had trouble starting and went through the whole rigamaroo (air leaks, dirty carbs) and the battery tested good but in the end wouldnt hold a good charge. Also you said there are no air leaks around the boots, how ever how do the rubber diaphragms look in the carbs? a tiny tare in one of the diaphragms can cause a whole lot of headaches. (I am assuming that the bike has CV carbs like most 80's scoots)

 

[Guest]

The battery is good, just a year old. I charged it. I was able to get it started, but again it won?t start unless I put my hand over the hole in the air filter intake. I then after it starts, I have to move my hand a little to allow more air flow to keep it running, else it dies. It just makes no sense, to me anyway. Sunday afternoon, running almost perfectly and idling. Then later that evening, back to square one - can?t get it to crank. Now, it will crank, but only as described above... ughhhhh.