Poor idle, can I sync carbs?

[zaphoid42]

First I am new to ridding or driving anything with carbs...

Around Sept. Nov. last year I knew the bike was running poor.  It would take a long time to warm up and need the choke on (about 1/4) for the first few min. of a ride.  Without the choke it would stumble comming off idle.  It would also occasionally die when at a light.

New job and new house and so on and so on. So the bike was used very little.  It had stabil in the tank and run for a good 10 min.  Sat un loved untill now.

The bike is a 2002 GSF600.  Stock everything, no adjustments made to the the pilot screws.  7,500 miles.

Took the bike out of the garage.  It started after a few tries and needed a lot of choke just to idle.

Went back into the garage and replaced the fuel and air filters.  Replaced the stock NGK plugs with the same.  Checked the valve clearances.  Found only three tight exhaust valves and re set them.  The old plugs, with all 7,500 miles on them were blacker than I would like.  The ceramic around the center electrode was black to brown, whole thing covered in black carbon.  Not fouled, just not good.

Bike back out of the garage, fires right up and runs OK with the choke on.  After a long time it can idle without choke but sounds nasty.  The number three exhaust pipe is not as hot as the others.  Sounds like its missing at idle.   Open the throttel without the choke and it will die. Took it around the block and when you can get it off idle it pulls like a champ.

Drained the fuel from the carbs and put in "fuel system cleaner"  let things sit over night.

After draining the cleaner, no diffrence.

Can carb sync. be my problem?

Can I sync. with the number three cylinder is doing whatever its doing?


Plugs showed rich, yet need lots of choke just to idle, what gives?

[CWO4GUNNER]

[Red01]

First off, B6's are notorious for being cold-blooded with stock jetting... but this is from being too lean. Sounds like you're not that lean though. First on the agenda would be to figure out why.

Don't bother with a sync until you can get #3 to run in the ballpark of the others. You'll need to figure out if it's a spark or fuel issue and correct it.

[rider123]

Before you sync I suggest putting some fresh gas and some sort of carb cleaner in there and go for a ride. Try to go on the highway with rpm's in the mid range with some quick spurts to really get those jets flowing. Take it for a 15 minutes highway ride then go home and check the plugs. You may want to clean your air filter just to eliminate that possibilty befor you ride. You'd be suprised what a little highway ride and an air filter clean will do to gummy carbs. Get those jets a-flowin'!!!!!

The plugs may be showing rich because the amount of time on the choke and a dirty air filter. Clean the air filter go for a high speed ride come back then check the plugs. Carbs don't go out of sync all that much if you haven't adjusted them.

[CWO4GUNNER]

[zaphoid42]

The heat was out in the house today, stayed home from work.  Will snow later tonight.  Pulled the bike apart waiting for repair man.


The new air filter is still clean.

There is a tube that runs from the air cleaner box down to the ground.  Has a plug in the end.  When I pulled that plug 2 table spoons of fuel/oil goo came out.

How did this get into the air box? All of it through the oil breather?

The last time I ran it, it had fresh gas.  A 10 min run around the block twice.  I can hit 60 in second gear, its a big block :-)

Pulled some plugs out to have a look.  The number three plug is covred in a glossy black coating.  The stuff is sticky but does wipe away.  The plug has been firing, I can see that on the electrodes.

The rest of the plugs are OK super fine.

If the coil for #3 was bad, would #2 (same coil) also recive week spark?

So, is it oil or fuel on the plug?  Next step in diagnosis please?

[rider123]

That tube you pulled with some oil and water is the airbox drain tube. Yes a shitload of water and oil will come out there due to condensation and the restricive nature of the stock airbox its perfectly normal just be sure to empty it once every couple of months. Once you open up the airbox condesation has a chance to escape and there won't be nearly as much condensation. I pulled out the snorkle a couple of times while shimming my needles for my new muzzy aftermarket can and when the snorkle was out there was hardly any water buildup at all.

If you want you could try the "Italian tuneup trick" What you do is park your bike in your drive way and rev the bike up to around 6-8 thousand rpm's then close the throttle when the revs are high and put your hand on the snorkle to stop any air intake. This will creat a shitload of vacuum which will suck up any crud in the carbs. It's an old Ducati dell'orto carb trick. Water vapur used to seep in those carbs like crazy, this would quickly clear the carbs, hence the "Italian tune up"  

I'm pretty sure it's a carb issue as if number 3 had a bad spark from a wonky coil so would number 2. You could try popping in new plugs but I would try the "Italian tune up" method a couple of times for fun, it saves alot of time if it gets the crud out of there. Befor doing the "Italian tune up" I would drain the float bowl of number 3 carb then put the bike on prime to  let some gas flow freely through and out of the float bowl on number 3 to clear any crud in the float bowl.

[kev25v6]

check that all your plug leads are tight where they connect to the coil pack, my old bike had similar problems to this and it turned out to be a bad connection. sometimes it could be simple things that are missed. hope this helps.

[zaphoid42]

I am intrested in replacing the spark plug wires.  I look up the wires in the electrical tab of ron ayers and see parts is parts.

Is there a way to buy a complete already made up set?

[zaphoid42]

Ok, I am still lost.  I had taken the bike out for a good 100 mile ride.  Mostly freeway 70 mph plus.  Bike seams normal to me, but what do I know.  If I pull over and flick some water onto the exhaust, the water sizzles away imediatly - except on the number three pipe.  Water drops will hang around on it for a little while.  To hot to want to touch, but its not going to melt fingers like the others.

All the plugs look the same, no way to tell which plug from what cylinder.

So, I no longer think electrical.  I redid the valve clearence to make sure it was not something stupid I did.  All  valves are right, and they move when the cam is rotating and everything.  I measured the TPS resitances.  They are just like the manual says.  I took the carbs off and wanted to see what was going on with the number three.  I took the cover off the top and removed the piston/diaphram/spring.  No holes, tears that I can see.  Took the float bowl off and measured the float height.  Seams right to me.  Removed the float.  I can up through the bottom of the main jet to where the needle should be.  Looks clean to me.

During bowl removal I screwed up a couple of screws and had to take the dremmel tool out. :-(

Because I mess up so easily, I dont want to go on and "inspect" the other carbs.  I also do not want to remove the main, pilot, or slow jet.  Way to much chance of messing things up.  I also dont want to drill out the pilot screw plugs.  Pilot does not sound like my problem.

Also, I noticed that the oring around the float bowl is thicker than the part I ordered up.  13258-26E00 seams really small in diamter compared to whats there.  I will reuse the old and hope for no leaks. Putting the throttle cable linkages back on will be a royal pain.

I am wating for new intake pipe assemblies that connect the carbs to the engine.  A while ago, I found shamootz on the outside of the carbs (engine side), and I tried to tighten the clamps.  Tightend them to clamp limit, but they were easy to turn.  I am replacing all clamps and the #1 and #3 pipes.  My thinking is this might be a vacume leak.

For what its worth, the carb sync. screws had yellow paint on them staking them in position.  

I am asking for a little direction.  My current plan is to reassemble when the intake pipes arrive.

No plans after that though.

It was a nice day for a ride.  Wish I could have gone......

[kornjulio]

Zap -

I'd strongly suggest you get the #3 carb completely apart and inspect/clean the pilot and main jet....By chance, I'm in MI and can help out if you're somewhere around Grand Blanc/Goodrich....

[zaphoid42]

Put the carbs back on.  Hooking up the throttle cables is a real pain.  Other than what the manual says, is there a better way to ajust them? Some kind of logic...

Any way, the bike rips along great.  But the number three pipe is still cooler than the others.  I plan on putting another 100 miles on it before I look at the plugs again.

I want to do a compression test.  There is a suzuki adaptor listed for the compression gauge.  Is there a cheeper way to go?  How does one get the "autozone type" fitting in and then get the hose on it way down there?

Has anyone actually used an IR temprature measuring thing on their pipes?  Just would like to know.

kornjulio, I am some where in metro detroit.  I ride fast to avoid the bullets, urban renewal, large brand new SUV's and idiots.

If the plugs come back with nothing visible, then I will continue to ignore the whole issue.

[zaphoid42]

Maybe I did some good after all, because I just burned my fingers on the number three pipe.


From now on, I hear by swear, to always blast along on the highway for 15 min on every ride.  To use a bottle of carb cleaner once a year.  To perminantly attache some hoses to the carb drains and at the beginning of every season let fresh fuel flow freely.



I guess it was a "junk" in the carb and my cleaning did some good.

[tacoman]

if you want to check compression try a tool rental outfit.  I needed to do a check on my Gixxer 1100 and rented a kit, $10 for 24 hrs.  It had all the adapters so I did my car too.