Uneven Idle

[ken]

Hi all
I have developed a slightly uneven idle and uneven constant rev i.e. at 2000rpm it seems to miss slightly.
Plugged into tune ecu and found no faults other than unbalanced throttle bodies which I have now sorted at a constant 630. There is still uneven idle not massive but enough to get on my nerves.
This all started when I rode in a rain storm and the bike was hunting on constant revs,
any ideas as to what could be wrong

ken

 

[warp9.9]

Ken your explanation is a little confusing to me. First I would check clean and re-crimp all low tension leads to the coils they get loose and create inadvertent idle misses which will make the rpm bounce around. Now if your talking about the idle getting stuck at about 2000 rpms until you shut her of and restart then I would get a new primary throttle position sensor.

 

[nicko]

There has been a few writeups on the forum regarding reclamping ht leads, i would further suggest you remove each ht lead and ensure no water has calcified on the contact point, cleaning and retensioning as you go, then do 12 min base tune take for a ride come back let her get cold and retest, also check your fuel... seems to be happening a bit

 

[nicko]

To further add, buy a can of "start ya bastard" it contains ether, carefully spray around intake manifold and where any vacuum lines may be hiding should there be a vacuum leak it will start running like ****, keep spraying area till isolated

 

[ken]

Ken your explanation is a little confusing to me. First I would check clean and re-crimp all low tension leads to the coils they get loose and create inadvertent idle misses which will make the rpm bounce around. Now if your talking about the idle getting stuck at about 2000 rpms until you shut her of and restart then I would get a new primary throttle position sensor.

The rpm is not getting stuck its uneven at all revs as well as idle, I will check all the leads again as you suggest as I could not get at the front one, I have also done the 12min tune

 

[ken]

To further add, buy a can of "start ya bastard" it contains ether, carefully spray around intake manifold and where any vacuum lines may be hiding should there be a vacuum leak it will start running like ****, keep spraying area till isolated

That is a very good idea thanks

 

[Speedy]

Ether is very volatile and if there is the smallest spark you are in for a very large surprise. Better to use a small propane plumber's torch, un-lite of course, with the valve only slightly open (adjust to small flame and then blow out flame.) Move the pencil tip close to each hose joint and even along each hose while the motor is running. Any vacuum leaks will suck in the propane and raise the rpm. Much less explosive and better directed to a small area.

 

[nicko]

That is a very good idea thanks

No probs you can also use brake cleaner, i dont like using it as its much more corrosive and can damage rubber seals hoses and paintwork if not cleaned off thoroughly.

 

[nicko]

Ether is very volatile and if there is the smallest spark you are in for a very large surprise. Better to use a small propane plumber's torch, un-lite of course, with the valve only slightly open (adjust to small flame and then blow out flame.) Move the pencil tip close to each hose joint and even along each hose while the motor is running. Any vacuum leaks will suck in the propane and raise the rpm. Much less explosive and better directed to a small area.

Ether is very volatile but more effective than using most sprays, if you are careful it is great, if you are spraying it on or near a spark then i would say you should not be playing around with it in the first place. Propane, butane, brake cleaner will all ignite should a spark be apparent... the spray i am talking about is directly marketed at spraying into intakes or down carbies to help identify fuel/ignition issues. It contains a small percentage of ether which i would think be less volatile than a propane gas bottle with the valve open. Either way its all a risk.