Misfiring/spluttering around 4-5k

[TravisBickle]

Hi guys another one then, partially linked to the last one.

So my bike has developed some odd behaviour. The last time I took it out for a proper ride it was behaving fine the whole time and right up to and including parking up on my drive and turning it off etc.

Next time I came to use it, it started first time, then cut out after about 5 seconds. After that it wouldn't start up. Well I did eventually manage to get it running but only after cranking it for a very long time, giving it a short rest between goes. When it did eventually fire up it seemed to run fine on idle but as soon as I took it up to around 4-5k (whether it be on its stand in neutral or riding it in any gear) around that 4-5k mark it would lose power, cough and splutter, feels/sounds to me like a misfire or a fuelling problem. If I am able to get past the 4-5k mark it seems to run fine at the higher end of the rev range it's just that middle bit that's the problem.

I've changed the spark plugs and this hasn't made a difference.

Three things I would mention:

1) Even from when I first got the bike a couple of years ago, when cruising on the motorway at say around 70mph, it would always cruise fine but if I gave it an absolute fistfull while already doing about 70mph it would usually (not always) give one, only one, splutter, like a very brief fuel starvation only for a fraction of a second, would jerk my body forwards because of the sudden back-off in acceleration and then it would get up and go again fine. As I said it's been doing that for since I first got it but never around town or 40/50mph roads giving it a fistful at lower speeds in lower gears never got that sensation of a fuel starvation judder, only when already doing motorway speed. I don't know if this is linked, like an existing problem that was always there but has suddenly got worse.

2) It has been very wet lately, I had to blow a shitload of water and crap away from the top of the spark plugs before I removed them, there was literally a swimming pool collected in the spark plug recesses just from it being parked up in the rain. I'm not sure if the problem could be water-related.

3) The carb rubbers are cracked and have been since I got the bike. I don't THINK they're cracked all the way through as the rubber is quite thick but I can't be 100% sure. Looked on Fowlers for some new ones but they wanted about £80 each IIRC!!! Copied the part number and looked around including eBay and Amazon for some cheaper genuine ones but couldn't find any reasonably priced. Normally only go for genuine parts but this would probably be more than the bloody bike is worth so I begrudgingly got some cheap Chinese copies off eBay for £20 for a set of 4. They look a pig to fit though so will probably wait for a Sunday with some reasonable weather and have at it armed with the Haynes bible.

https://i.ibb.co/dMMv3Gf/20191015-200445.jpg

https://i.ibb.co/2WpQNdN/20191015-200434.jpg

Any ideas what might be the cause? Think I'm barking up the wrong tree with the carbs?

All help and advice gratefully received!

[Nobby the Bastard]

When were the valve clearanes last checked?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[TravisBickle]

[TravisBickle]

I just think it's strange it was fine the whole time the last time I used it. Not until a few days later went to start it up after it had been raining very hard that now I am having problems. That's why I'm thinking water ingress somewhere is the cause...???!!!

[Nobby the Bastard]

Try starting it from cold and check the temp of the pipes, preferably with a temperature laser gun thing.

Any cylinders that aren't firing will warm up slower than ones that are.

Bear in mind that it's not much slower if the pipes are Connected.

This will identify if its a global or local issue.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[TravisBickle]

I haven't got the tool to do that. Might need a trip to the mechanic... He's a bit lazy and prefers me to order the parts if possible (actually he's not really lazy he's just very old school and not very computer-literate so finds it easier if I supply the parts for him). Already got the rubbers. Anything else I will need if it's carb-related? Gaskets or whatever?

[Nobby the Bastard]

The odds are it'll be electrical or mechanical (valve clearances). Id be very surprised if carbs just suddenly go like that overnight.

The leakey rubbers won't help but the usual symptom of air leaks is cutting out when shutting the throttle to pull up.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Tdibs]

Easiest way to see if the rubbers are completely gone, spray wd40 right on the cracks when it is idling. If it cracked through the revs will change. But yes, they are on the way out, better to change them out.

To your original problem, I would inspect the HT leads. Pull the caps from the sparkplugs, unscrew the wire from the cap, inspect if its all green and corroded or nice and shiny copper. If its all horrible, you can trim off the end of the lead slightly and screw back in.

If the Carb boots are that far gone, plug leads/caps might be suffering also.

Usually the cause of giving it a handful and it bogging and dropping a cylinder, then kicking back in.
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Previous : 09 Vanvan 125| 02' Sv650s || Current: 1999 Xj600n | 1992 DR650 RSE | 2005 Fazer 1000

[Easy-X]

I have some rubbers I bought for my failed Fazer project. They're only cheap Chinese copies but you're welcome to them if they'll be of help.
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[TravisBickle]

[TravisBickle]

So the bike went to the mechanic and he found water in the system. A LOT of water. Dirty water and the petrol was cloudy. He drained the tank, removed the carbs, cleaned them up etc. Bike is back together again now and the symptom remains but to a slightly lesser extent. He's showed me how to drain the carbs with the little screw on the side of each carb. Carbs need draining before every time I use it. If I go to use it without draining the carbs it will splutter around 3-5k. If I manage to get it above 5k it seems ok at the top end of the rev range and as long as I keep the power on it rides ok. Drain the carbs before using the bike each time and the bike will run fine, until the next time I park it up and turn the engine off. After it's been parked up and turned off the next time I use it carbs will need draining again, even if only 15 minutes have elapsed i.e. stopping for petrol. But the bike seems to run fine until it's been turned off and left a short while. There's water in the petrol every time it's drained but both the water and the petrol are coming out clean now so although the tank has been drained and the carbs cleaned there's clearly still some water coming from somewhere. He said he didn't bother removing the fuel pump as in his experience as it's a 20 year old pump often you go disturbing parts like that after 20 years you find you put them back and they're no longer working any more so thought it best to leave it alone along with the filter rather than disturb it.

I'm happy to change the filter but apart from draining the carbs before every use is there anything else I can do to help get rid of the water? I'm thinking eventually if I keep draining it before every use eventually I should get the last of it but there seems to be no light at the end of the tunnel at the moment. I reckon I must have drained them a good 10 times or more and still water keeps coming out after every time I've used it.

Can you get fuel additives that will help with this?

[Nobby the Bastard]

How is water getting into the tank?

You did throw the contents of the tank away and refill with completely new fuel didn't you?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[TravisBickle]

[TravisBickle]

He said there is a breather under the tank for the carbs which could have been the source of water ingress but he reckons unlikely as although water could go straight into the carbs from here if presented but because it's under the tank it's fairly well protected and unlikely to allow water in, even in a heavy downpour.

[Nobby the Bastard]

Where is the water coming from? It can't just be coming from nowhere.

And don't say up the breather pipe, how is it getting into the breather in the first place?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[TravisBickle]

I don't know. He has a couple of theories but no conclusive evidence of the cause. Personally I would doubt it's getting in through the carb breather as if that was the case surely draining it once would cure the problem? As the water keeps coming back only logical place it can be coming from is the tank???

[TravisBickle]

https://www.amazon.co.uk/WYNNS-FUEL-WATER-REMOVER-325ml/dp/B01M0E2F2T

Anyone had any experience and success with this???

[Nobby the Bastard]

You need to solve where the water is coming from before you do anything ekse. Has it been raining constantly since you've had it?

The water must be coming from somewhere.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Easy-X]

It's not going to be something daft like E10 (higher ethanol content petrol) affecting an old bike?
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Nobby the Bastard]

[Tdibs]

Wipe the tank fill cap seal/inside of the fuel cap completely dry with a paper towel.

Pour some water over your fuel tank, open it back up and check for any ingress. Might be seeping through the key barrel slowly or the seal is gone.

This sounds like multiple issues though, if you have known fresh fuel in, drained the carbs and ran it a few times, should be purged the majority of the water out already.
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Previous : 09 Vanvan 125| 02' Sv650s || Current: 1999 Xj600n | 1992 DR650 RSE | 2005 Fazer 1000

[Grubscrew]

Water could be coming from condensation build up in a tank if left for long periods less than full, due to atmospheric temperature outside, the bikes components will take time to adjust to the same temp causing condensation.
If you can put an in-line see through fuel filter in do so. (Cheap)
As for the carb rubbers: any small split going through the rubber will cause erratic running. And yes try the wd40 , it works. ( also a cheap fix)
If the carbs need a clean, find/ buy/ borrow a sonic cleaner with cleaning fluid....you’ll have to dismantle the carbs totally, take pics as you go to remind you of placements of bits.
The other cheap thing you could do is use a satellite fuel tank and run engine, in the dark (turn the lights out) and look to see if there is any arking of sparks etc across to the frame whilst running/ revving.
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FJR1300/CBR1000F

[Nobby the Bastard]

Enough condensation to cause the carb to need draining wouldn't have built up in the 9 days since this thread started, let alone since the tank was emptied by the mechanic.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[TravisBickle]

[Andy_Pagin]

I'd avoid jumping to the conclusion that there is just one thing wrong that's causing the symptoms. I had a similar problem at about the same mileage, in my case it turned out that the spark plug caps where knackered, one actually fell to pieces when I gave it a gentle squeeze. A new set of caps costs about fifteen quid or thereabouts? Wouldn't do any harm to change them.
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They're coming to take me away, ho-ho, hee-hee, ha-haaa, hey-hey,
the men in white coats are coming to take me away.
Yamaha Vity -> YBR125 -> FZS600 Fazer -> FZ1-S Fazer