Running lean with sooty plugs

[badeaslava]

Do all 4 spark plugs look exactly the same everytime - dry but sooty ?

yes all sparkplugs look pretty much exactly the same, sooty and dry. I'm also not visibly burning oil, it could be burning a little bit but the level in the engine didn't visibly decrease.

The stock jetting for my bike are not the ones in the manual

http://www.thegsresources.com/_forum/attachment.php?attachmentid=37165&d=1415990699

i was suprised too, but they are the same as this guy's

http://zachsgs650.wordpress.com/2012/09/08/cleaning-the-carburetor/

So i started with 110 mains and went down in size to 105, which caused my bike to sputter and cough and not accelerate, so i figured i was running lean. but even when running with that small jetting my plugs were black. Don't understand how. so now i am running with 120, the bike pulls hard but very black plugs.

If i were to have a leaky head gasket could air be getting in through there and causing a climbing idle and sooty plugs. The idle becomes erratic only when the bike is warm, so i'm suspecting some sort of thermal mismatch between components causing a gap to be created and air sucked into the cylinder. I tried squirting carb cleaner everywhere to find the source of the leak and was unsuccessful.

[Steve]

There was a suggestion made six weeks ago, in post #2, to do some plug chops. I have not seen any further mention of them, let alone any ressults. How about it?


The reason for plug chops is to isolate the various circuits in the carbs. Example: You might have some overly-large (or mis-adjusted) pilot jets and some small main jets. It will start easily enough because of the rich mixture, but when you go out for a ride and nail the throttle, it will stumble, because it's running lean. You will come here and say "it seems to be running lean, but the plugs are sooty". That is because you ran part-throttle and idled the engine before shutting it off. Doing plug chops will stop the ignition process during one particular phase, so you see the results of THAT circuit, not any others.

In your case, I would start with some new plugs. Mark the throttle grip and its housing for 1/4 and 1/2 positions. With the bike already warmed up, install the new plugs, go for a ride, but do not get the throttle over 1/4, just idle through town at about 1/8 throttle, if you can. Hold the throttle as steady as you can for as long as you can. When you get to some place that is safe to pull over, hit the "kill" switch, pull the clutch and coast to a stop. Pull the plugs and check their color.

Repeat this for 1/4 throttle. You might have to find a mild uphill section where you can put the bike in 4th or 5th gear, so it does not run away with 1/4 throttle. About 30 seconds of this should give decent results. Again, hit the "kill" switch, pull the clutch, coast to a stop in a safe area, read the plugs.

Repeat this for 1/2 throttle. You may have to find a steeper hill or drag the brakes a bit, but 4th and 5th gears are still your friend here.

Repeat this for full throttle. Good news here is that one clean run should be enough to let you read the plugs. 3rd gear will let you get through the entire RPM range without getting too obnoxiously fast. 4th or 5th gears will let you pull a little longer.

Hopefully you have also taken some paper to record your notes or just take some pictures. Let us know what you find.

.

[badeaslava]

Thanks Steve, i appreciate the detailed instructions for the test. I haven't done it yet cause i was thinking my throttle shaft seals or the dynojet kit will solve all my problems and it's getting a bit chilly here on the eastern coast to do much riding at high speeds. I'll def give it a shot as soon as i can and take some pics of the plugs to share it with you guys.

[Joe Guilbeau]

yes all sparkplugs look pretty much exactly the same, sooty and dry. I'm also not visibly burning oil, it could be burning a little bit but the level in the engine didn't visibly decrease.

The stock jetting for my bike are not the ones in the manual

http://www.thegsresources.com/_forum/attachment.php?attachmentid=37165&d=1415990699

i was suprised too, but they are the same as this guy's

http://zachsgs650.wordpress.com/2012/09/08/cleaning-the-carburetor/

So i started with 110 mains and went down in size to 105, which caused my bike to sputter and cough and not accelerate, so i figured i was running lean. but even when running with that small jetting my plugs were black. Don't understand how. so now i am running with 120, the bike pulls hard but very black plugs.

If i were to have a leaky head gasket could air be getting in through there and causing a climbing idle and sooty plugs. The idle becomes erratic only when the bike is warm, so i'm suspecting some sort of thermal mismatch between components causing a gap to be created and air sucked into the cylinder. I tried squirting carb cleaner everywhere to find the source of the leak and was unsuccessful.

Systematic troubleshooting is what will get it done.

What are your float height settings?

What causes a sooty plug reading?

Why not go back to original specs for the carb, they ran pretty good when they came from the factory.

Why the focus on the #110 main jet size? Have you contacted Zach to chat with him to find out if he checks his plugs out?

Stock engine that was issued with #97,5 Main Jets with aftermarket pods...and now with #110 Main Jets? That is a pretty good leap. Perhaps the manual was edited? My thinking is that with only aftermarket air filter pods, you are probably looking at going up 3 jet sizes..., going up 4 jet sizes equates to about adding "10" to the original Main Jet. So a three size increase would be around a #105.

If you original main jet size was indeed #110, then go ahead and go with a #120, however your plugs tell a different story.

Also today's gasoline is not the same as in years past, ethanol etc has a marked effect. Start with a warm engine and one new plug into an outside carb, set the float height on THAT carb, as well as 2.5 turns out on the pilot air jet and the #105 Main Jet before warming up the engine with the OLD plugs in.

Start the engine, she will idle and let her idle until she is very warm, kill the engine and report back with the result on idle mixture setting. It is okay to go a bit lean on the idle mixture, because you don't ride on idle, so that circuit is out of the picture. If the plug is STILL sooty, you other problems that increasing the Main Jet size will not cure.

If the plug looks good, then take her for a spin, run her up to 2500-3500rpm and simultaneously release the throttle, thumb the kill switch, put her in neutral, coast to a safe place (you are in a WalMart parking lot...right? Take a look at your mid range carb settings...Rich or Lean?

Float height is critical to carb performance...just ask around.

[Joe Guilbeau]

yes all sparkplugs look pretty much exactly the same, sooty and dry. I'm also not visibly burning oil, it could be burning a little bit but the level in the engine didn't visibly decrease.

The stock jetting for my bike are not the ones in the manual

http://www.thegsresources.com/_forum/attachment.php?attachmentid=37165&d=1415990699

i was suprised too, but they are the same as this guy's

http://zachsgs650.wordpress.com/2012/09/08/cleaning-the-carburetor/

So i started with 110 mains and went down in size to 105, which caused my bike to sputter and cough and not accelerate, so i figured i was running lean. but even when running with that small jetting my plugs were black. Don't understand how. so now i am running with 120, the bike pulls hard but very black plugs.

If i were to have a leaky head gasket could air be getting in through there and causing a climbing idle and sooty plugs. The idle becomes erratic only when the bike is warm, so i'm suspecting some sort of thermal mismatch between components causing a gap to be created and air sucked into the cylinder. I tried squirting carb cleaner everywhere to find the source of the leak and was unsuccessful.

Here are my main jet sizes, I guess I should just ignore the Technical Service Manual produced by the engineers at Suzuki who apparently do not know as much as a guy who posts video's on YouTube...my mistake.

GS1100EX Stock Jet Size.jpg

Jest sayin, go thru the carb tutorial, learn something and get it right the 1st time, or just keep posting and randomly shot gunning the issue.

[BigD_83]

Looking forward to seeing your plug chops (pictures if possible). That is really going to be the best way to see what is going on.

For my own clarification, why do you say that the "stock" main jet size was #110? Where did that number come from? It is listed as 97.5 on all of the charts/manuals I can find online. The 110 on the website you mentioned is on a 650GL.

[badeaslava]

THank you for all your replies, i apologize i didn't mean to waste your time just trying out different jet sizes and willingly ignoring the service manual data. So the reason i think my bike had 110 stock mains is because that's what it had when i purchased it, with the stock airbox and everything. THe bike is 650EZ from 82, i searched online and couldn't find anything on the forums stating the exact jetting for this model bike. A different forum states the jetting for the GZ/GLZ 650 of the same model to be #110 i figure the only change from the G to E is the chain drive but the engine shouldn't have changed.

http://www.thegsresources.com/_forum...-manuals/page2 (its in Eliseo Monteverde;s post)

I suppose there's a slight chance that the previous owner swapped the stock carbs on my bike with carbs from another model but it's very small. THis is why i was using #110 mains as my gold standard.

I will try though swapping 105 in there and running just on idle and reporting back what i get. I'll have to order those jets though since i dont' have them anymore, so that will take a little bit of time for shipping.

Joe, i checked float heights both on emptied bowls and using a bench method with a clear tube with the bike running. THey seem to be all within spec. I guess what worries me more is the hanging rpm that was there on the bike the entire time, even with the stock airbox, which seems to be contradictory with the running rich issue. But i'll try to sort out the sooty plug issue before i handle the hanging rpms.

[Steve]

Is this not the bike in your signature?

You are now confusing me, it's not usually quite that easy.

THe bike is 650EZ from 82, ...

yet, your sig says it an '81 650E.

Which is it?

It won't change the jetting needs any, just trying to keep things straight.

.

[badeaslava]

Is this not the bike in your signature?

You are now confusing me, it's not usually quite that easy.


yet, your sig says it an '81 650E.

Which is it?

It won't change the jetting needs any, just trying to keep things straight.

.

it's the same bike Steve, i must have entered the year in my sig incorrectly, its the 82 model with the designation Z, so it's EZ.

[Steve]

OK, but now you should be aware that saying it's an '82 ... Z is redundant.

The denizens of this forum and the geekiest parts monkeys are probably the only ones that understand the Z at the end.

Most everybody else will understand "1982 GS650E".

.

[badeaslava]

So i've finally gotten around to do a spark plug chop test on my bike per all of your suggestions. I installed 105 main jets on the bike and cleaned the sparkplugs with a brass brush practically before each plug chop test. The plugs are new, i just bought them they just get fouled with unburned fuel very rapidly so i have to clean them to see what's what.

This is with 2.5 turns out on the idle mixture screw and 105 mains. After 5 mins just idling the plugs were very sooty. After about 1/2 throttle on an uphill for maybe 10 sec, the plugs were sooty still. After wide open throttle for about 10 sec, the plugs looked clean, with very minimal carbon deposit. So i figured it's gotta be the idle mixture, so i turned down the mixture screw to 0.75 turns out and went up to 115 main jets (what i had lying around) and it seems like a miracle happened. The hanging rpms disappeared, the bike doesn't die on stop lights anymore and holds a 1100 rpm idle quite well. At about 1/2 and on throttle the engine looses power from what seems to be a lean burn, so i was thinking to increase the mains to 117 (like in a previous post by member GSX1000E) I rode the bike yesterday for about 20mins and pulled the plugs, they are still a little sooty, but much better than before, maybe i have to turn in the mixture screw some more.

Another new update is when the bike is idling and i pull the choke out, it dies. Why does that happen? Is the engine instantly just flooded with too much gas from the choke circuit?

So what do you think i should do for the idle jet, clearly i need to decrease it, unfortunately i have no idea which one i have in there right now. The factory manual says 42.5 should be in there, is there any way to check, wire gauge?? If i were to decrease it would i go down 2 sizes? Should i mess with the idle air jet at all? it's 160 right now.

I think the fact that i'm still running lean with 115 mains confirms the fact that my stock mains were 110 as opposed to 97.5 (as in the factory manual).

[Joe Guilbeau]

After wide open throttle for about 10 sec, the plugs looked clean, with very minimal carbon deposit.

So, with Wide Open Throttle (WOT) for about ten seconds the plugs are clean? Right? So, the 105 Main Jets are spot on...Doh!


So, now is the time time to put that #105 main jet back in because it is the only circuit operational at wide open throttle.

Now it is time to adjust the Pilot Air Screw in ONE carb when the bike is warm. Adjust that Pilot Air Screw until the one carb's spark plug is nice and clean at idle. Measure the turns...CAREFULLY by doing 1/4 turns to seat the Pilot Air Screw. Use that setting for the other three.

Now you have the Idle and the Wide Open Throttle set with the #105 Main Jets and the correctly determined Pilot Air Screws for your Idle.

So, the only thing left is the Mid-Range which is controlled by the raising and lowering of the Needle.

[badeaslava]

I suppose I'm confused then Joe, with 105 mains the bike wasn't pulling at all at WOT, like the engine just turned off after a point. I thought that's a sign of a lean mixture, unless you think that my needles are just set to really lean. I don't think that 10 sec at WOT would result in white burned plugs, am i wrong? Even at 115 mains it pulls much better than with 105 but still there's a point after which seems like the engine just turns off.

[Joe Guilbeau]

So I missed that data point (with 105 mains the bike wasn't pulling at all at WOT), I read that they were no long sooty, just pretty clean.

[megatwin]

Have you checked your valve clearances?