GS750E running rich

[Rustybux]

My GS750E is running rich. Checked floats and they were too high..reset all them to 25mm as the book says. Still they carbon up the plugs. After a 50 mile highway ride, checked plugs, black and carbon coated. Checked timing and points and they are all fine. What else can do that?

[odl777]

possibly a bad carb sync but if its all four plugs probly not. I would go to you needle jet. I am haveing the same problem and check all the things you did, all thats left is the main jetting or the needle jets. good luck

[Scud]

What did you do to the carbs, if anything, before this problem arose? And were they ok before you did any work to the carbs?

Scud

[wiredgeorge]

The dreaded sooty plug issue! OK... let's look at this issue a bit. Why do you think it is carburetor related?

It can be from MANY other things that should be checked before "adjusting" carburetors which are at the tail end of the tune up cycle.

First, soot on your plugs is from poor combustion. The things I see that cause poor combustion are:

1 - Poor compression caused by lack of valve clearances. Valves are slightly open due to lack of clearance. Compression is lost and combustion is incomplete. When was the last time you checked valve clearances???

2 - Poor spark... spark plug has 3 functions: 1 spark 2 clean combustion chamber via heat 3 remove excess heat. If you have a weak spark, it will only give you partial combustion AND the heat generated will not be sufficient to clean the combustion area. The result is quickly fouling plugs. THE most common reason in older bikes for poor spark is that the coils do not get full power. The route for voltage to the coils goes through a BUNCH of connectors, your igntion switch and kill switch. Over time, as corrosion and age get to these components, you will get less voltage. Take a look at this link AFTER you have checked your valve clearances:

http://kzrider.com/component/option,com_docman/task,doc_details/gid,106/Itemid,231/

3 - OTHER STUFF! Plug fouling can also be caused by your mechanical ignition advance being sticky. It needs to be removed, cleaned and lubed from time to time. Fouling can also occur if you have the wrong BRAND and heat range spark plug. USE the BRAND and HEAT RANGE specified in your owners manual. Using off brand plugs often results in the wrong heat range due to a poor cross reference system. In other words, DO NOT use Autolite or Champion plugs. Use NGK or ND. Last thing that comes to mind is your air filters. OEM air filters need to be pitched once in awhile when they get a bit dirty. You choke off the air to your carbs and you will have sooty plugs. Emgo pods should be treated the same way and they have less surface area than an OEM filter so should be pitched even more often. A K&N or UNI filter should be cleaned and re-oiled when dirty AND if you re-oil, don't use too much oil as that is also another effective way of turning off the air!

Good luck