Erratic idling in traffic

Hi all, I would appreciate some help please.
My bike performs great under normal driving conditions but when in heavy traffic and travelling very slow and stop starting the tick over goes very lumpy as if the engine was only firing on one cylinder. Often I get a smell of raw petrol, On revving up the engine fires normal again but every time if still in traffic it goes back to being lumpy. when just pulling up at junctions and lights etc. tick over is normal, only happens when travelling at slow speed for a while. Have fitted new plugs and air filter but to no avail.
Any ideas please.
Thanks in advance.

Barry

Sounds like a fuel issue to me. 1st step would be to adjust the idle (FSM pg 5-104). 2nd step would be to check the vacuum hoses for leaks (pg 5-95). 3rd step would be to balance the throttle body (air screw syncronization, pg 5-103). 4th step check the Fuel Pressure Regulator (pg 5-102).

Please let us know how you get on with this. We all benefit from shared information

Tim

Cosmic_Jumper wrote:

Sounds like a fuel issue to me. 1st step would be to adjust the idle (FSM pg 5-104).
2nd step would be to check the vacuum hoses for leaks (pg 5-95).
3rd step would be to balance the throttle body (air screw syncronization, pg 5-103).
4th step check the Fuel Pressure Regulator (pg 5-102).

Please let us know how you get on with this. We all benefit from shared information

Tim

+1 from me, idle too low was the first thing I thought of.

Hi thanks for the info Tim, I have set the idle speed and checked for leaking vacuum hoses and all seams ok.
I don't have the special tools to do the rest. Funny part about this fault is that I can let the bike stand ticking over for half an hour and it does not show any problems, as I say its only when crawling along in traffic that I get the problem, I think it may be over fueling as I get the smell of raw fuel until I give it a bit throttle and the tick over returns to normal for a while.

Here's a link to a previous discussion regarding throttle body (air mixture screws) balancing.
https://www.silverwing600.com/t9532-throttle-body-balance-the-cheapskate-way?highlight=Manometer

Sounds like it has a misfire. Plug wire or cap leaking some voltage. It will idle fine all day but when engine is loaded misfires. Does it lack power on acceleration when this is happening?

Look at plug wires and caps over plugs for any kind of burn marks or cracks...

Hi, no loss of power at any time, I will have a good look at the plug leads and caps as you advise.
Many thanks

All very odd, I think I'd start by removing the right side lower body panel & checking the condition of the HT leads & the feed wires at the coils







[Admin comment] +1 to The Bern's advice. Especially given the age of the scoot.

My 2013 Swing smells of raw gas when in heavy stop and go traffic. It only happens in warm temps. I think it is the evaporative canister. My 2002 Swing also did it.

Very strange. Misfire will cause bike to run like crap.

Raw fuel smell is a problem. Canister is designed to trap vapor from tank not venting it to atmosphere..
System has a purge valve that will open after engine is hot and pull this back in to be burned off.
Canister is filled with charcoal bits that absorb vapor. Canisters can become damaged from excess fuel or water.

Canister could be damaged and when purge valve open its pulling in excess fuel. Guessing???

My 2013 SW never smell any fuel.

A very full gas tank on a hot day, maybe a loose gas cap gasket = fumes ?

oldwingguy wrote:

A very full gas tank on a hot day, maybe a loose gas cap gasket = fumes ?

I agree. That steel bar in tank prevents fuel nozzle from going in to far and possible damaging something.
BUT I also think tank is full at that level. I sometimes fill it a little more when just stopping for fuel and plan to keep riding.. Tank is behind radiator its warms up a bit in traffic.

Just trying to help.

Well I have done all I can without the aid of special tools, I have run the bike in the garage for 1/2 hour and used brake with slight throttle to try and simulate in town traffic conditions, all went well perfect tick-over with no smell of fuel, All I can do now is take it for good run and see what happens.
I will let you know how it goes.
Thank you all for your tips and suggestions they were very helpful.

Regards to all, Barry