Very Tricky Situation... Input would be much appreciated.

[kb_air]

So many things, I'll just pick a few.


We just can't say it enough. If you "need" starting fluid, FIX THE BIKE. What you have just seen is a very MILD case of what can go wrong. What's worse than setting your bike on fire? How about blowing it up?


You have your jet increases backwards. Your main jets are the ones that should go up multiple sizes (maybe to a 120 or so) and your pilot jet might need to go up just one size, but usually not.


Why are you idling your bike for hours? With your pilot jets about five sizes too big, it's no wonder that it's idling rather rich.


The pilot jets affect your idling and up to about 1/4 throttle, which is really a LOT of your basic running, especially around town.


The pilot jets do not determine the idle speed.


Black soot on the inside of your pipe is not going to affect air flow. It merely indicates that your bike is not jetted correctly and that is going to affect how it runs.


No, but an engine that is running rich enough to make it carbon-encrusted will.


Get it jetted properly, get a new set of plugs and be done with it. Cleaning plugs with a wire brush will leave metallic traces on the porcelain, possibly short-circuiting the plug. That could also be contributing to your poor running.

When you get new plugs, make sure you get the correct ones, NGK B8ES.


In that case, it has been in there too long. The filter is a rather generic one that can be gotten at virtually any Suzuki shop, many places on the internet, even eBay. I think they only made one filter that fit all their bikes from about '76 to '86.


Were the floats measured from the correct location? What measurement did you use?
Did you dip the carbs or just spray them out?
How do you know they have good airflow?
You only sync the slides visually to get the bike running. Then you must use a set of vacuum gauges.
The pilot fuel screws (the ones on the bottom) should be out about 1 to 1 1/4 turn for your setup. The pilot air screws (the ones on the sides) should be about double that.
Adjusting the idle mixture screws "in sync" is not always good. You have to tune each carb to itself, they might all have slightly different settings when running their best.


It is VERY MUCH a matter of carb adjustment.

First, get the proper jets in there. Mains should be about 120, you say you have 117.5s in the mail. Start with them. Pilots should be 15. Stick with them. Pilot screws set like I suggested above. New set of spark plugs. Change the oil and filter, go ride that thing.

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what he said

[Steve]

Alright I'll definitely try those settings. By turns do you mean full 360 degree turns or 180 degree turns?

"Turns" are full, 360-degree turns.

Do you think I need to adjust my jet needle at all?

No idea. Only plug chops will tell. You will have to get it running on the needle circuit long enough to color the plugs (NEW plugs help this process), then pull them out to see the color.

Also, I assume I'm getting good airflow from my new pod filters, ...

You do know what they say about "assuming", right?
I am presuming that these might be UNI brand filters?
Do they need to be oiled?
Have you oiled them?
If they are oiled too much, air flow will be restricted, possibly severely.
Do NOT assume.

..., and the floats are at 27 mm from the interior edge of the float bowl without the gasket.

Any particular reason you set them to 27 mm? Specs for your year call for 25-27 mm, so 27 will be on the lean side of the range.
You might want to raise the floats (set to a lower number) 1 mm, if possible. Yes, it really does make a difference.

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[MK3Brent]

For what it's worth, also...
Using a wideband O2 sensor makes all this guess work disappear when you're trying to size your jets properly. For less than $150, you can pick up an LM-1 or whatever they're calling it these days (LC-1 with gauge), and add the bung into the manifold collector.

As far as scratching the dielectric on the spark plugs, you don't have to worry so much. We're talking several kV of potential that sparks a .032" or so gap. The inception voltage through air is approximately 3kV/mm. In the extreme (relative to atmosphere) pressure in the combustion chamber this value will increase. If you have an insulation flaw due to scratches or other semi-conductive elements on the surface, you'll puncture the porcelain before it causes other issues like missing.

[ThunderBaird]

Thanks everyone for all of your help, I got a hold of the appropriate jets, fixed some leaks, and tuned up the fuel mixture (which was pretty close to how ya'll said it should be.) The bike is now in fully functional form, and I will be riding it very soon.

[Steve]

As far as scratching the dielectric on the spark plugs, you don't have to worry so much. We're talking several kV of potential that sparks a .032" or so gap. The inception voltage through air is approximately 3kV/mm. In the extreme (relative to atmosphere) pressure in the combustion chamber this value will increase. If you have an insulation flaw due to scratches or other semi-conductive elements on the surface, you'll puncture the porcelain before it causes other issues like missing.

I wasn't all that concerned about scratching the porcelain, I was more concerned about a steel wire wheel leaving minute metal deposits on the porcelain that would provide an alternate path for electricity, possibly bypassing the spark gap.

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