Need a bit of help with GS750

[motionboy]

I have been having intermittent starting issues where if the bike is cold it just would not turnover, even with choke. However, if it sat in the sun it would start right up, no problem. I also used to have to just hammer on the starter and wind the throttle to get it to start

So I decided to take the carbs apart for a good cleaning. While I was at it I monkeyed around with the idle plate position, if it is not set to the right position could that be causing this problem? Now I have been unable to get the bike started at all. FYI I do have the air filters off thinking it might help. If I let it sit for awhile it tries to fire but then does nothing.

Any help would be appreciated, I am pretty new to carburetors.

[motionboy]

Is it possible that the problem is my spark plugs. They are only 2 months old, but were fairly black and sooty, I am assuming b/c my bike is running way to rich, but 2 months?

[spyug]

Welcome aboard.

I'm a little confused by your description. It wouldn't start when cold but would if left in the sun to warm up? You also mention the idle plate position can you explain more? When "monkeying around" with the carbs did you refer to the carb cleaning tutorial on the main page? The tutorial would give you the proper procedures for cleaning and adjusting the carbs and is the only way to do the job properly.

It sounds to me that you have two issues in addition to a wonky starter ( did you check and clean the connections from the solenoid to the starter?). The carbs and fuel system sound like issue one and I'm betting your valves need adjusting as this is usually the main cause of hard starting.

On these bikes the carbs work best with a properly fitting airbox and clean filter ( or pod filters) so I'd a) properly clean and adust the carbs as per the tutorial b) connect the airbox with clean filter c) adjust the valves as per the tutorial on BikeCliff's website.As you mention, sooty plugs is indicative of a rich running condition so when cleaning the carbs you might want to ensure you have the right jets installed.

An additional problem causing hard starting can be low voltage at the coils causing a weaker spark and or fouled plugs. I would also replace the plugs and if time permits check for voltage drops to the coils and do the coil relay modification ( do a search there is tons of information on this ).

It seems like there is a lot to do but there are no quick fixes if you want it to start easily and run right. Get the carbs properly cleaned and adjusted first and go from there. A bit at a time and you'll have it sorted I'm sure.

Good luck.
Spyug

[Seanie]

Hi,

I had very similar issues 4 weeks ago with my 750e.

You will need new plugs anyway, but that wont solve it fully.

Valve adjustment and clean carbs was the advice I got too, which is very good advice I might add!

But my trouble was a leaking petcock, allowing too much juice, and "flooding" the engine.
I had the same type of starting stuff- plenty of power in the battery, had to open the throttle nearly fully to get it started at all, and if it flooded and wouldnt start I had to leave it sit fot about 40mins, and then have another go, which ment riding to work was out the window and was a bit of a let down on a nice dry morning!

But, since I sorted out the petcock all is back as it should be. I try it first without choke and trottle closed, and once I hear it about to kick in I only give it choke then. Bike starts every time, first time. Dream machine!

[BassCliff]

Hi,

I concur with the above. GS happiness starts with clean carbs, adjusted valves, a tight air intake system, clean electrical connections, and a healthy charging system (battery, stator, regulator/rectifier). If your spark is weak then a coil relay mod may be in order. Can you give us a little more history on the bike and what maintenance you've done to it?


Thank you for your indulgence,

BassCliff

[motionboy]

Thanks guys. I find it hard to believe but it was the spark plugs. They weren't NGK, they were champion equivalents, and were quite sooty for only being two months old. However the carb cleaning I did has the bike running great now that there is spark. I am going to have to wait until tomm. to see if it is still running rich, in which case I may need some new jets.

[cowboyup3371]

Why would you need new jets if it is running rich? You should just be able to tweak the carbs instead.

[BassCliff]

Why would you need new jets if it is running rich? You should just be able to tweak the carbs instead.

Hi,

The size of the jets is what meters the amount of fuel in the fuel/aix mixture ratio. There is only so much "tweaking" you can do.


Thank you for your indulgence,

BassCliff

[tom203]

I have been having intermittent starting issues

So I decided to take the carbs apart for a good cleaning. While I was at it I monkeyed around with the idle plate position, if it is not set to the right position could that be causing this problem?

Any help would be appreciated, I am pretty new to carburetors.

How did you conclude that "the idle plate position" was not "right" ? If you have stock CV carbs , the throttle plates would be just about 100 % closed at normal idle. If you monkeyed around with them and they are open too much, hard starting is going to add to your other problems.

[BassCliff]

How did you conclude that "the idle plate position" was not "right" ? If you have stock CV carbs , the throttle plates would be just about 100 % closed at normal idle. If you monkeyed around with them and they are open too much, hard starting is going to add to your other problems.

Yes, this makes sense. Perhaps a "bench sync" followed by a vacuum sync (after valve adjustment, of course) is in order.


Thank you for your indulgence,

BassCliff

[Seanie]

I did change my plugs too...But after a day or two my problem was back. But see how you get on. Like I said below, problem was my petcock...