carb mixture
- Thread starter Hans_77
- Start date
Do you mean bright red on the plugs?? Never seen or heard of red on a spark plug. Maybe you can post a picture? Never had to adjust mixture on mine, so other carb experts should chime in here.
EDIT: See the next post below about setting carb mixture in the UK. Might be of help.
EDIT: See the next post below about setting carb mixture in the UK. Might be of help.
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http://hkar.ru/Baw3 you can see a photo here.
The plug doesn't look too bad actually. Doesn't appear that it is misfiring from being wet, although the carbon build up around the edge looks a bit excessive. I believe to set the mixture screws, you need to pull the carbs off the bike. Before going there though, try this. If you can get a carb cleaning product, try running a dose or two of that in the fuel tank to see if it will clean the carb internals. It could be that old gas has deteriorated from sitting in the carbs and caused some varnish to plug up the jets.
A popular one on this side of the world is called Seafoam. Be sure to use something that is safe for the carburetors non metallic parts. That may clear up your problem, without having to dig the carbs out.
Martin may know of a product on the European market that would suit your need. Martin?
A popular one on this side of the world is called Seafoam. Be sure to use something that is safe for the carburetors non metallic parts. That may clear up your problem, without having to dig the carbs out.
Martin may know of a product on the European market that would suit your need. Martin?
"pull the carbs to set idle mixtures" is absolute mis-information. Difficult to access, but to set mixtures CORRECTLY it HAS to be done with air cleaner and housing assembly in place, and ALL hoses, vacuum etc. included as it's normally ridden. Aside from that, as Bush stated, some SeaFoam in fuel MAY help, IF in fact there's anything wrong associated with the carbs. Age of bike, and not knowing whether carbs have previously been off or not, a vacuum leak(leaning out mixture) WILL make it run lean.....AND eventually 'hole' a piston. The carb boots on these scoots are a very common source of a vacuum leak with age at their mounting base on head. Normally not enough to cause piston damage.......just enough to affect running AND overall fuel mileage
.I believe a PROPER carb sync is in your future, and CANNOT be correctly done unless idle mixtures are re-dialed in first
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I stand corrected, as I said, I had never needed to do such myself. Glad someone else chimed in.
I've seen another thread that you have posted, plus this one. I'm thinking you'll need to start with the basics. We'll need more information about the history of this bike. Is the engine in a good state of tune? EX: valves adjusted, carburetors synchronized, new filters, plugs, fresh oil? etc.... I would start with a complete servicing of the engine before you condemn carb mixtures....
I took a look at the plug pic you posted. The red tint that you see on the ground electrode is from a fuel additive. Either from your local pump supplier, or from a conditioner you've put in the tank. Very common. You have either a platinum or an iridium plug in there now. The ground electrode is worn and rounded. Time for new plugs.
Freshen up the engine's state of tune and report back on driveability...
I took a look at the plug pic you posted. The red tint that you see on the ground electrode is from a fuel additive. Either from your local pump supplier, or from a conditioner you've put in the tank. Very common. You have either a platinum or an iridium plug in there now. The ground electrode is worn and rounded. Time for new plugs.
Freshen up the engine's state of tune and report back on driveability...
+1 on above- Get a new set of plugs before you do anything else. If you do mostly high speeds, you may want to go one heat range cooler on the plug type. That's what I run, BTW.
AND - The "mixture" screw only affects the idle and very low speed mixture. So looking at the plugs tells you basically what the mixture is that IS NOT determined by the "mixture" screw. Add some fuel injector cleaner ( I know your bike has carbs ) to the gas for a few tanks to help clean the carbs.
In the USA, most folks use the Seafoam brand. Is it available in Russia ? If not, you can use any good concentrated fuel injector cleaner - just follow the directions as far as how much to add to a gas tank the size on your ST1100. You could make it a little more concentrated than the directions say, without causing a problem.
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ST1100Y
Site Supporter
Well, I've no info about the avail supplies in Russia, but here in central Europe is no such thing as Sea Foam avail...
The automotive suppliers and hardware stores do carry some fuel additives, "mileage improvers" and "EFI system cleaners" by STP and such MFGs, so one needs to seriously search for a true carb cleaner additive...
If all fails one must go with the DIY home-mix with Isopropanol, Petroleum and others (recipe is avail in the Inet)...
Another issue could be general fuel quality; again do I miss any first hand experience with Russian gas stations, but I had my issues with Czech, Slovakia, Hungaria and all around former Yugoslavia... fuel in all named is know to be generally contaminated, often having a high water content... (I managed to seize up the injectors of my company car over there, according to my workshop where the needles rusted up like been recovered from the bottom of the ocean... must have picked up some wet fuel...)
So to complete the chain here: lets also focus on bad fuel and all the symptoms & efforts connected with that.
I'd go systematically, step by step:
- inspect the inside of the tank, the bottom in particular, for debris/contamination...
- check the fuel filter, replace if required
- check the diaphragm of the auto fuel valve, a rupture can cause intermittent stops in the fuel supply.
- check the carb boots/isolators, as well as every other vacuum sided hose and line for cracks or leaks... drawing "false air" is always a problem and would fit the symptoms...
(note: SC26 engines do have a PAIR system; due this their known to produce some silent rumble while coasting/deceleration with "engine breaking", but that's only a soft "blum-blumblum-blumblumblum" in the exhaust, no sudden bangs, no misfire and no bogging connected with that; and ST1100 is always smooth as an electric motor... )
- there is no general mixture adjustment on CV carbs; their factory set by main-jets, and that usually works perfectly...
- only the idle jets offer a mixture setting, this should not cause any issues during operation, only causing problems in idle, maybe issues during gear changes, but no bogging at acceleration...
- opening the carbs for cleaning/inspection could be risky due to a slow supply on spares over there, but depending on evidence collected in tank and fuel filter it might be unavoidable.
The issue is that you'll likely need new gaskets once you open the carb bowls... but you might need to for cleaning the bores of the jets.
Same when inspecting the carb diaphragms, they might have swollen in size/diameter (fuel quality, ethanol additives, etc...) so once you've opened the top covers, new diaphragms are due...
If the engine shows bogging, backfiring and such, something is off...
Also possible is an intermittent contact on one or both ignition coils (bad crimp, corrosion, etc...), which are located behind the steering head.
When already diving into there, give als the big mains connectors (LH & RHS switch pod, and ignition lock are joining the bike's mains harness there) a visual and cleaning/protection with a designated solvent (no WD-40!! Some proper contact cleaner/care product; ACF-50 is great in that regard)
The spark plug looks good so far, but it still could be that one has a cracked isolator, causing an intermittent "shunt" thus lack of spark on one cylinder bank (like when water has filled up the spark-plug holes underneath the caps after washing; the still cold engine coughs and bogs with that, once warmed the water evaporates and the symptoms are gone.
The automotive suppliers and hardware stores do carry some fuel additives, "mileage improvers" and "EFI system cleaners" by STP and such MFGs, so one needs to seriously search for a true carb cleaner additive...
If all fails one must go with the DIY home-mix with Isopropanol, Petroleum and others (recipe is avail in the Inet)...
Another issue could be general fuel quality; again do I miss any first hand experience with Russian gas stations, but I had my issues with Czech, Slovakia, Hungaria and all around former Yugoslavia... fuel in all named is know to be generally contaminated, often having a high water content... (I managed to seize up the injectors of my company car over there, according to my workshop where the needles rusted up like been recovered from the bottom of the ocean... must have picked up some wet fuel...)
So to complete the chain here: lets also focus on bad fuel and all the symptoms & efforts connected with that.
I'd go systematically, step by step:
- inspect the inside of the tank, the bottom in particular, for debris/contamination...
- check the fuel filter, replace if required
- check the diaphragm of the auto fuel valve, a rupture can cause intermittent stops in the fuel supply.
- check the carb boots/isolators, as well as every other vacuum sided hose and line for cracks or leaks... drawing "false air" is always a problem and would fit the symptoms...
(note: SC26 engines do have a PAIR system; due this their known to produce some silent rumble while coasting/deceleration with "engine breaking", but that's only a soft "blum-blumblum-blumblumblum" in the exhaust, no sudden bangs, no misfire and no bogging connected with that; and ST1100 is always smooth as an electric motor... )
- there is no general mixture adjustment on CV carbs; their factory set by main-jets, and that usually works perfectly...
- only the idle jets offer a mixture setting, this should not cause any issues during operation, only causing problems in idle, maybe issues during gear changes, but no bogging at acceleration...
- opening the carbs for cleaning/inspection could be risky due to a slow supply on spares over there, but depending on evidence collected in tank and fuel filter it might be unavoidable.
The issue is that you'll likely need new gaskets once you open the carb bowls... but you might need to for cleaning the bores of the jets.
Same when inspecting the carb diaphragms, they might have swollen in size/diameter (fuel quality, ethanol additives, etc...) so once you've opened the top covers, new diaphragms are due...
If the engine shows bogging, backfiring and such, something is off...
Also possible is an intermittent contact on one or both ignition coils (bad crimp, corrosion, etc...), which are located behind the steering head.
When already diving into there, give als the big mains connectors (LH & RHS switch pod, and ignition lock are joining the bike's mains harness there) a visual and cleaning/protection with a designated solvent (no WD-40!! Some proper contact cleaner/care product; ACF-50 is great in that regard)
The spark plug looks good so far, but it still could be that one has a cracked isolator, causing an intermittent "shunt" thus lack of spark on one cylinder bank (like when water has filled up the spark-plug holes underneath the caps after washing; the still cold engine coughs and bogs with that, once warmed the water evaporates and the symptoms are gone.
ST1100Y
Site Supporter
If he'd damaged them or installed the wrong type...
For the ST1100 they should be NGK-3797, CR8EHIX-9
other then this its probably not essentially related to your misfire issues... there still could be other items related, as listed above...
So that's one thing in need of been taken care of...