rough idle when hot

[peppiiino]

hi all,

my bike starts fine, when cold the idle is around 900, then when hot it goes to around 1100-1200 but then after 15 20 min ride the idle becomes rough: when stopping at a traffic light sometimes it gets stuck at 2000 for few seconds and then goes back to 1200 for few seconds, then up again..,
other times just stays at 2000 and then to 1200 and that's it, other times it keeps revving at 2000 for ages

what shall i check first? carbs? valves? something else??

[Superjack44]

Try tightening the clips on the carb to cylinder head mounting rubbers you might have a slight air leak

[peppiiino]

Hi thanks for the reply,

I didn't have time to tighten them up yet due to work and rain, however i saw that the 2 external are easy to reach, the internals are not i may need to remove the tank.

I heard there are some kind of rubber sprays that can fix the leak if is the rubber that causes this, does it work?

[Superjack44]

Hi thanks for the reply,


I heard there are some kind of rubber sprays that can fix the leak if is the rubber that causes this, does it work?

Sorry never heard of that

[peppiiino]

hi,
so I tried to thighten up the clips but they were very tight.
however i noticed that this issue lasts for a minute or so and the it sorts of stabilise, very weird..

[peppiiino]

Just read it in another post, as I have a KN filter could that be the cause of the rough idle????

[peppiiino]

Any ideas? could the K&N filter causes the rough/high idle issue?

[craigs23]

Have you had the plugs out to check the mixture?

What sort of condition is the air filter in?

Are you getting a good spark to each of the plugs?

Has the bike been sat for a while too? Gummed up carbs?

Have you put a voltmeter across the battery terminals when the bike's running (i.e. to check the rectifier)?

I tend to start with the basic checks first, before contemplating things like valve clearances and what not.

[peppiiino]

Hi,
the sparkplugs as well as the filter look ok,
didn't do any electrical test, however the bike is perfect on this side, never had a problem

I just got curious because in another thread is mentioned that a K&N filter would need rejecting...
is it true?