Running rough at lower revs, seems rich from the plugs, float level queries

[Nebuchernezzer]

So I've just joined this forum and would you know it a day after I join I have an issue with the bike.


It only just happened this morning and i'm yet to do much investigation (cos i'm at work now), but I thought I'd throw up my symptoms.


-Hard to start this morning (25 degree weather, usually fires up first go)
-After starting ran on 3 cylinders until i gave it a rev.
-Faint smell of hot oil perhaps, my sense of smell isn't very good so it could be something else.


Up until now I've had no issues, i think i might have smelt the smell yesterday on my way home but i dismissed it as being from another car (i commute in a fair bit of traffic)


Bike is a 99 FZS600, 80,000km (50,000miles), standard apart from yoshi slip on, K&N filter.  Recently i've fitted a new fuel filter (a few weeks ago, that's how long I've had the K&N in for as well).


All i've done is have a look around the bike in the carpark after i got to work, no visible leaks, carb rubbers look all solid and secure, basically externally it's all clean.  Oil level is all good, water level is all good too.


So my plan of attack is:
Pull the plugs, read them, probably replace them cos why not (should tell me something surely!)
Check the HT leads with the multimeter.
Comp test cos it'll be easy to do with the tank off and plugs out as well.
Go from there.


While i have the tank off I'll likely balance the carbs, check the valves (and hope they don't need adjusting cos well i don't want to haha)


What's everyone's thoughts?


EDIT:
Doesn't appear to blow any smoke, looking over my shoulder and opening her up (safety first!) as I came in to work today.

[His Dudeness]

Start it up and leave it to warm up then throw some water on the headers and see which one dries slowest that'll tell you what cylinder has the problem. After that check the plugs, leads, caps. You could try swapping them around one at a time to another cylinder and see if the problems follows. Carbs would be the next thing if none of that works. It's not likely to be carb rubbers, valve clearance or compression imo

[stevierst]

My Thundercat did similar until lat night.
She was a Bugger to start, and ran like Shit on constant throttle (stuttered/vibrated until throttle opened). There was also a stronger than normal smell of fuel.

I stripped it all down and inspected the diaphragm rubbers, checked for air leaks etc, etc.

It turned out that the carbs for some reason were well out of balance (only did them last week).

I'm not saying that's what's wrong with yours, but start with the simple stuff first. It's got to be better than stripping the whole bloody thing down like I did.

Good luck

[Nebuchernezzer]

I've decided it's probably fuel I can smell,  seems to have a whip about it even at main road speed.
It only ran on three for probably a second or so and I blipped it and it went away.
I changed the plugs tonight (started fine this arvo by the way), and the old ones didn't look too bad.  The right colour (that tan look),  one was a bit gummy around the top but there is a very slight rocker cover leak around number 3 it seems. Had a bit of a fight with a tiny bit of gravel that had wedged itself in next to the plug but I won in the end.
Carb rubbers look excellent.  My compression tester doesn't fit the small diameter plug holes so didn't try that.
It's probably not been balanced in ages so I wanted to do that however over fuelling or leaking fuel into the bore overnight perhaps could be the problem?
Maybe I'll pull the caarbs and clean them up etc.
Oh and I discovered one of my Carb to airborne clamps is missing but I can't see it causing much issue. I'll replace it regardless.
And the plugs below.

[stevierst]

I reckon balancing the carbs is the first place to start, sounds suspiciously like they're out of balance for one thing.

[Nebuchernezzer]

I'll do that asap then. And excuse any random words in my posts I miss some of my phones autocorrelation sometimes

[His Dudeness]

Are the electrodes on some of those plugs badly worn down in that picture or is it just the angle they're at?

[Nebuchernezzer]

Just the angle,  they weren't too bad really.
Made myself a Carb synch tool today,  checked the tps and it's out but I've not got any torx bits.
I'll get some tomorrow and set thay and balance the caarbs and ride it work this week and see how it is.
Started it today and no 3 cylinder running,  just normal. It's only done it once so we'll see how it goes over the long run ay.

[darrsi]

Been some heavy rain recently, is it possible water has found it's way into a carb?

[Nebuchernezzer]

Nah no rain,  and from the design of the air box with that rubber around it and the snorkel I think I'd have to just about drown the bike to get any water in.
It was on a fresh tank of fuel which made me wonder about the servo I filled up at a little (not one I usually go to),  but it's a long shot that it's bad fuel I think.
It happened to my mum once though,  got contaminated fuel pumped into her car, it didn't like that! Servo had to pay to flush it all out.

[darrsi]

Nah no rain,  and from the design of the air box with that rubber around it and the snorkel I think I'd have to just about drown the bike to get any water in.
It was on a fresh tank of fuel which made me wonder about the servo I filled up at a little (not one I usually go to),  but it's a long shot that it's bad fuel I think.
It happened to my mum once though,  got contaminated fuel pumped into her car, it didn't like that! Servo had to pay to flush it all out.

You would not be the first person on here with water in the tank or carbs, and we all have the same bike, so don't totally rule it out!

[Jules-C]

Mine tried the running on 3 cylinders trick a couple of years ago. Turned out to be dodgy plug cap

[Nebuchernezzer]

Wow it must have been some hardcore rain!
I'll keep it in mind .
I did notice the plug caps seemed to spin relatively freely on the wires as I took them out,  so I'll sus them out and if they are loose on the wires I'll cut a bit off the ht lead and refit them before I do my balance.
Do the caps ever die or is it mostly the connection between them and the ht lead that gives out?

[Jules-C]

The plug caps can die the resistor built in can fail or dirt inside cap can get spark to track down inside of cap instead of through plug. If you take the caps off and put them back on different leads then if the problem is still there on the same cylinder you know it's not the plug cap but if the problem moves to another cylinder then it's the plug cap

[darrsi]

Wow it must have been some hardcore rain!
I'll keep it in mind .
I did notice the plug caps seemed to spin relatively freely on the wires as I took them out,  so I'll sus them out and if they are loose on the wires I'll cut a bit off the ht lead and refit them before I do my balance.
Do the caps ever die or is it mostly the connection between them and the ht lead that gives out?

Quite a few people have replaced them, including myself, and fortunately it's a very cheap mod. compared to £55 EACH from Yamaha. 


This is the correct one.


http://www.ebay.co.uk/itm/1x-NGK-Resistor-Spark-Plug-Cap-SD05F-red-8238-/230778918900?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item35bb7ed7f4

[Nebuchernezzer]

I'll check the connections today and perhaps just change the caps later cos for that price why not? 80,000km on the bike I feel that I should just replace stuff as I go along.

[Nebuchernezzer]

Well this is what happened over the weekend:
Replaced the plugs.
Cut 5mm off the end of each plug lead and refitted the caps so they don't just spin freely.
Set the TPS, it was out.
Tried to balance the carbs but they are so far out of whack that number 2 managed to suck all the oil out of my makeshift balance tool.
I could mess around with it and make it work i'm sure but since i really want to have the bike balanced before i go to work tomorrow (i rode it today and it's well a bit rough) i'll probably just go buy some vacuum gauges on the way home.  I can get away with just two gauges to sort the bike out so yeah...
The only adjustment i managed to do before the bike decided to gulp the oil down was a slight tweak on 1-2...those screws on the adjustment are damn sensitive actually!
So anyways tonight....balance it, live the dream of smooth running...woo.

[Nebuchernezzer]

Well this has been a bit of a saga in the end.  Tried balancing the carbs with a tube type a balance,  basically 4 silicon tubes,  all t pieced together with oil in them. But it was pretty out of balance and sucked all the oil out through one of the tubes.. Fail!
Then I tried some vacuum gauges but they weren't accurate enough so I tried a bottle type one,  basically tubes going to glass jars full of water,  the setup doesn't allow the engine to suck the working fluid in,  so bonus. It was quite hard to balance,  very touchy,  and the fact the bike is a daily means I've been using it out of balance too. So I didn't get far with that,  decide to replace the plugs again in case one was fouled (it was) put some stuff in the tank to strip water out of the fuel (just in case, it seemed to make a difference actually so perhaps there was some in there.)  checked the water drain from the fuel cap,  rebalanced it.. Twice and yeah,  now see how it goes. Seemed ok on a ten minute test ride today but we'll see after riding it to work for a week.

[darrsi]

Well this has been a bit of a saga in the end.  Tried balancing the carbs with a tube type a balance,  basically 4 silicon tubes,  all t pieced together with oil in them. But it was pretty out of balance and sucked all the oil out through one of the tubes.. Fail!
Then I tried some vacuum gauges but they weren't accurate enough so I tried a bottle type one,  basically tubes going to glass jars full of water,  the setup doesn't allow the engine to suck the working fluid in,  so bonus. It was quite hard to balance,  very touchy,  and the fact the bike is a daily means I've been using it out of balance too. So I didn't get far with that,  decide to replace the plugs again in case one was fouled (it was) put some stuff in the tank to strip water out of the fuel (just in case, it seemed to make a difference actually so perhaps there was some in there.)  checked the water drain from the fuel cap,  rebalanced it.. Twice and yeah,  now see how it goes. Seemed ok on a ten minute test ride today but we'll see after riding it to work for a week.

99% Isopropyl Alcohol is the cheapest option for removing moisture from a tank, which in turn will also combat carb icing if you're ever unfortunate enough to experience it. It binds with any water and simply gets burned off as fuel. 200-300ml per full tank will do the trick.
Don't bother with stuff like Silkolene Pro FST, it's just way overpriced and in my opinion not as effective as the IPA.
Make sure it's the 99% one though, as there's also a 70% version which has 30% distilled water in it.

[Nebuchernezzer]

Awesome ill keep that in mind . I'll also get some plug caps,  I cut down the leads and refitted the caps (they were spinning freely before) and I could see no evidence of track marks but there is some ticking noise evident when I had my head near the motor doing the balance so I'll change them anyways. For the price why not,  the bike has 80, 000km on it so why not refresh a bunch of things right?

[Nebuchernezzer]

So once again this morning the bike is running crap, i'm thinking that perahaps one of the fuel bowl needle/seats is leaking because it almost compression locked on start today, then started up rough, once running it's fine over 4000 or so RPM but rough below and at idle it's rough as well.  I don't think it entirely drops a cylinder but it's hard to tell.
Yesterday i had the bike at idle for a significant period of time (to balance it) and it was ok (occasionally rough but couldn't tell if that was just it being out of balance or not), during my test ride yesterday it idled happily and pulled smoothly at all RPM, although i'm not convinced that's the smoothest it could be still.
It appears number 4 is the one that's leaking, simply because when i changed the plugs yesterday it was fouled, number 1 was a bit dirty, 2 and 3 nice and clean and 4 filthy.  I assumed at the time that was simply bad balance flooding one cylinder but now i'm not so sure.
Anyways how hard is it to either get the carbs out or to change parts on the carbs with them still in the bike?

[Nebuchernezzer]

Checked the float levels on cylinders 1, 2 and 4 today (3 is a batch to get to but the others appear so far off that I'll have to remove the carries and set the floats anyways).
Pics below,  along with the corresponding Spark plugs. Plugs are only about 35km old.  I'm thinking I'll take the caarbs out,  replace the float valve and seat just cos they are out of the bike anyways and set the floats on the bench (cos who wants to put them in and out of the bike repeatedly?) should be possible to set the floats sitting on the bench as far as I can see, use a coke bottle as the fuel source and whatnot.
What do you guys reckon. They look miles off and the ones with a really high level seem more fouled than the ones with a lower level (the plugs that is).
Logical?
Number 1


Number 2


Number 4

[darrsi]

Running rough under 4000rpm and idle still sounds like the carbs are not synced to me.

[Nebuchernezzer]

Done the syncing,  several times in fact but I'm suspecting there is an underlying problem that means my syncing is for nothing until I fix it.

[darrsi]

Yep, someone pointed out on here recently that syncing will only work well if several other parts of the bike are functioning properly and in spec, otherwise you're just adding extra problems.