MISFIRE Steady riding 30mph 2nd gear 3000rpm HELP

[CouncilBacchus5]

Thanks Carl, I have just swapped a filthy standard air filter for a brand new standard air filter. Not had chance to test if the problem still happens with new filter yet. Will try watching the revs drop and see what happens. I have lightly blipped the throttle when cold and it bogs down and doesn't respond as you would expect. Like it cant cope with the fuel its getting. Iv put this down to the engine been cold as once its hot, it still has this but it is no where near as bad. barely noticeable to be honest once warmed up.

I was using the term misfire to describe what happens when holding the revs at a constant while in neutral around 2-3k revs the bike makes an unusual noise from the engine, coughs and splutters a bit and the revs drop slightly then return to where they should be. then it will do it again until it is warmed up where the issue seams to be gone. While riding along it also does this the feeling the get while on the bike is very unsettling a bit like when the drive chain chugs when an engine is labouring.

So we are thinking its the fuel mixture? Is that the pilot screw?

And then possible balance carbs and TPS?

Thanks again for your help everyone.

[lloydie]

Carb fart :-)

[VTRDark]

fuel mixture

As Lloydie said it's what is known as a carb fart, that's the search term to use And yes fuel mixture screw which is part of the pilot circuit. This is the fine tuning for the pilot jet. At 3000 your right on that transitional point from the pilot circuit onto the needles. You may find a 1/8 to 1/4 turn out on the fuel screws may just sort it out for you. Or leave as is, wait for Summer to arrive and it will most likely behave a bit better.

First things first, change that dirty old filter for the new one. It's no good doing anything until you have done that. It's real easy to lift the tank up or even remove it. Take note of where the small vacuum pipe fits on the fuel tap/diaphragm as it's a common mistake to put this back on the wrong outlet.

(:-})

[popkat]

The symptoms described are not carb fart. I've felt what the op is describing and it's more like a chugging, lurching while riding at steady throttle for the first few miles, once those miles are done it smooths out to normal. it maybe pair system related but on mine I blanked it all off and flipped the reeds over, it didn't do it straight away after removing pair system, maybe there is a small air bleed but my guess was mixture as it happens just at transition point between pilot and main jets, doesn't explain it clearing up after a few miles though, also doesn't explain it happening on a bike with standard pipes so maybe it is the pair after all, I think Mac is planning on putting earlier cam covers on his to see if it goes away.

[CouncilBacchus5]

I have put the new filter in and will test it again when I get chance.

Are these symptoms fairly common then and nothing to worry about?

As I mentioned before its been a while since Iv had a bike with carbs so cant really remember how they are to live with.

With the bike having carbs is it likely that any issues I am having are been made worse by the colder air temperature? I do remember my bandit many years ago not enjoying the cold and been a bit rough when warming up but its the first time iv ridden a twin with carbs. Are any issues with "Carb farts" going to be more noticeable and is it just the character of the bike?

Thanks again.

[lloydie]

The symptoms described are not carb fart. I've felt what the op is describing and it's more like a chugging, lurching while riding at steady throttle for the first few miles, once those miles are done it smooths out to normal. it maybe pair system related but on mine I blanked it all off and flipped the reeds over, it didn't do it straight away after removing pair system, maybe there is a small air bleed but my guess was mixture as it happens just at transition point between pilot and main jets, doesn't explain it clearing up after a few miles though, also doesn't explain it happening on a bike with standard pipes so maybe it is the pair after all, I think Mac is planning on putting earlier cam covers on his to see if it goes away.

Sounds like it's a little rich on the mixtures or lean .
:-)