Well, that's what it feels like .... Like it's only firing on 3 1/2 cylinders ... Very spluttery .... Any ideas where to start looking?

Plug, coils, carbs???

Can hear a definate mis fire in the engine on tickover that goes right up the rev range ....

Cheers all

 

Change your user name. LOL

OK, you have to ask yourself if you have ethanol in the fuel. You can smell it. Sounds a lot like you got some crappy fuel in the beloved.

That's for starters.

Also upping the jets one notch wouldn't hurt either.

That's just my opinion. As it gets colder out, the lean factory condition, with and if you have ethanol, causes hell.

Try a fuel stabilizer or injector cleaner in the fuel that's already in the tank to help burn it up and them go to another pump.

If you haven't done the stick coil mod, it's well worth the effort. That hot spark lights off the e-gas and stops the stumble.

 

+1 on the stick coils. Not sure if you can get seafoam across the pond but if you can that stuff works wonders

 

I did the coil swap. It took away the lumpy idle and the low rev stumble. Also, I run 92 octane and Seafoam two out of every three tankfuls.

Seafoam is the fuel tonic of choice around here. If not available, I'm sure the most reputable fuel treatment available in the UK should work.

Other than that, you may be looking deep into your carbs for the problem

 

Hey:

75 % of the time its dirty carbs with these bikes, but since you have a early model they have issues with the electric fuel pump too.. just remove it. Also the fuel could be bad as mentioned. Look inside of your tank and check for rust, check or add a new fuel filter. Lastly check to see if you have water contamination in the oil. then it could be a Head gasket. Good luck TS...

Dub

 

Dunno, I think if it's come on all of a sudden like, I'd be looking at coil/plug leads?

 

I don't know about elsewhere but the less well-known fuel distributors around here have been known to pass on contaminated fuel. I avoid 7-Elevens and Safeway for gas and stick with Shell or Union 76 only

May be a local problem, but if it came on all of a sudden it could be bad fuel

My experience with the fuel pump was a total failure without any preliminary ill-running. It was the contact points on the pump that failed. They can be replaced easily and the pump will be fine or as Dub said you can scrap it an go straight gravity feed

 

+1 on the gas. Sometimes my bike seems like a completely different machine when I get crap gas. For $8, I'd definitely try some Seafoam first, just because I'm cheap.

 

On a further note. I had an Interceptor, that I guess because of the design of the airbox, would collect rainwater and send it into my carbs. This has never happened on my CBR, but you might try draining your floatbowls into a rag and sniffing it for any off-odors

 

Thanks for the replys all ... but I really don't think it's the fuel, as it's been getting worse over the last 2 or 3 weeks ... I've filled up at various places ..... I use the bike every day, so it's never stood for long ...

No, this seems to be a physical problem ... there's quite a bad mis-fire on one cylinder ... I think I'll start by changing the spark plugs and see if that makes any difference ....

Keep the suggestions coming tho ... I need to find the problem

There's no water in the oil
There's no water in the airbox
Fuel filter is good

Cheers all