GS850 Carb ?

[Mike Curtis]

My bike is running a lot rich can I make any adjustment to the carbs to lean out without a jet change?

[chef1366]

It depends on what throttle position it runs rich. You need to do throttle chops with new plugs. Your plugs will tell the tale.

[Mike Curtis]

The bike is rich at idle explain what you mean by throttle chop?
Next question is where do I get the replacement for the vacuum operated petcock I would like to replace with a simple on & off arrangement.

[mark]

A little more to the story might be helpful.
Is your bike stock? What's the history? If everything is stock and its running rich, maybe there is some other problem......

Plug chops are a plug read where you run your bike at a certain throttle setting...not moving the throttle....to get the plug read at that throttle setting. Run your bike at a certain throttle setting for a couple of minutes on the road, shut down the bike (hit stop button) and coast to a stop and do the plug reads. Doesn't help to do a plug chop down the highway and then spend the last 2 minutes driving to your house. Different carb circuits operate at different throttle settings and it helps you locate the problem.

Others are more knowledgable than myself, but typical plug chops would be at around 1/8, 1/3 throttle (pilot jet and needle jet circuits). Main jets need to be tested at full throttle....I've never done that one.

Still, if your bike is completely stock and hasn't been messed with, I might start with something other than a carb adjustment. Plugged air filter, weak spark, side air screws out of adjustment, etc.

[dtkid]

Instead of replacing the petcock I always opt for a single in-line off/on valve. I allow the petcock to stay on at all times and use a one-way flow valve to control the fuel to the carbs. That way the petcock operation is never an issue.

I get the valves from Dennis Kirk.

[Mike Curtis]

The bike is stock except for an aftermarket tail pipe extention and I'm not sure about this piece of work done by previous owner my plan is to go back to stock on this piece don't like the sound.
Anyway number three and four carb was really rich discovered that the pilot screw on these two were maybe 5 to 6 turns from bottom (these are ones next to the intake boots on the top am really confused by these I'm certain that these will either lean or rich the carb. Number 1 & 2 were 2.5 turns from bottom.
I have a really strong ordor from the exhaust and a backfire which I think is a really rich mixture.
My objective is to get it running on a leaner mixture and have the nearest Suzuki mechanic here in the DFW area to balance the carbs and do some fine tuning.

[Billy Ricks]

The bike is stock except for an aftermarket tail pipe extention and I'm not sure about this piece of work done by previous owner my plan is to go back to stock on this piece don't like the sound.
Anyway number three and four carb was really rich discovered that the pilot screw on these two were maybe 5 to 6 turns from bottom (these are ones next to the intake boots on the top am really confused by these I'm certain that these will either lean or rich the carb. Number 1 & 2 were 2.5 turns from bottom.
I have a really strong ordor from the exhaust and a backfire which I think is a really rich mixture.
My objective is to get it running on a leaner mixture and have the nearest Suzuki mechanic here in the DFW area to balance the carbs and do some fine tuning.

After 4 turns you are off the jet completely and running full rich. ! 1/2 to 2 turns is usually a good starting point and the adjust from there for the smoothest, highest idle you can get out of each carb. If you get close to 4 turns out you need a richer pilot jet. If you get down to under about 1/2 turn out you need a leaner pilot jet.

[Mike Curtis]

Made the pilot screw adjustment to 1.5 + / - turns from bottom motor smoothed out a lot. Now developed a surge in the motor after warming up motor would pick up in RPM for a minute or two and then drop to about 1100 RPM an then idle. Can some explain the carb circuits to me.
Thanks

[mark]

My objective is to get it running on a leaner mixture and have the nearest Suzuki mechanic here in the DFW area to balance the carbs and do some fine tuning.

For 40-50 dollars you could get a carb synchronizer and do the "balancing" (synchronization) yourself. Its not that hard and you could save tons of money. Your valves need to be adjusted correctly in order to synchronize and compression needs to be relatively equal in all cylinders. Lots of people here could help you do it!

Normally, an increase in rpm's that gradually returns to idle indicates some sort of vacuum leak. This could be at the intake manifold boots, carb clamps, airbox or petcock vacuum line for example. All this needs to be right or your carb adjustments won't work well.

By the way for your bike, your airbox needs to be perfectly sealed. Check the seals around the airbox and make sure they are good. If they aren't go get some weatherstripping from the local hardware store and get an airtight seal. Make sure your clamps are on good too.

[chef1366]

This tells you all about the circuits.

http://auto.howstuffworks.com/framed.htm?parent=question377.htm&url=http://204.71.0.3/motoprof/moto/mcycle/carb101/carb101.html

[dtkid]

Hey Chef:
Nice link.......thanks....I needed something to read by the pool while I watch my kids drown each other.

[Mike Curtis]

I have installed new boots from the airbox to the carbs and as a precaution when starting this adjustment I wrapped the airbox side covers with duct tape to insure that I would not get any air leaks.
This would narrow down the possible vacuum leak locations. Need to go hunting.
Thanks guys for all your help