Heat + Traffic = Trouble

Back to riding after almost 23-years... Bought a second-hand 2004 SV650 K4 6-weeks ago for commuting and overall I'm happy with it - that is until the past week.

I've read through the forum because although I'm a 'newb', I don't want to ask the same questions all over. I've found the SV runs hot. I've found that the SV runs rich. I've found that the SV can start firing on one-cylinder for a whole host of reasons. But, I've not found anyone having the same problem as me.

My commute is around 100-mile round trip and the return leg is turning into a nightmare - a combination of heat and traffic turns the bike into something that's un-rideable.

The bike runs around 80 degrees C when travelling but rapidly heats up to the low 90s once in traffic. The fan cuts in and the temperature goes down, but very quickly it's back up in the 90s. Once it gets to the 90s, unless the revs are kept around 4000 rpm it'll cut out and die. Once it's cut out, it needs full throttle to get it started but then it's running badly - very, very badly.

When it's running badly, it's clearly running rich as the smell of petrol is overwhelming and there's plenty of backfiring which is usually followed by the engine cutting out.

In an effort to get this sorted, the bike has had a full service and a new set of plugs and i'm really not sure what to do next.

Any suggestions? Thanks.

[Craig380]

Hi, welcome and sorry to hear about the problems. So the bike runs well providing you don't get stuck in slow-moving traffic?

I wonder if the intake air pressure sensor isn't faulty, or if there's a problem with the pipe that links the sensor to the inlet. The IAP sensor is the one on the rear right-hand side of the airbox (as you're sitting on the bike). The ECU works out the fuelling based on three things - engine rpm, throttle position and intake air pressure, so if the IAP sensor is dodgy, it will throw the fuelling out. Might be worth checking the inlet hoses and clamps from airbox to throttle bodies and throttle bodies to cylinder are snug with no leaks, too.

The coolant temp sensor will also have some effect but it should fuel a little less when the motor is really hot ...

Sounds like it's either not running on one cylinder fully, or you have poor fuelling. Is it a pointy or curvy first of all?

[Blapper]

2004 = pointy init?

[Crawling Finn]

If it is not showing any fault codes I'd suggest that you try and change the spark plugs.

The plugs have already been changed according to the first post but it could certainly be an ignition coil, plug lead or cap. The rising temperature/fan operation etc is reasonably normal for these things and may be a bit of a red herring. Coils can work fine when cold then break down with a rise in temp. so it might be worth investigating these as well.

Good evening. Apologies for the radio silence but my father got taken in to hospital as an emergency but back with it now. Still struggling with the bike and in the end dropped it off with an independent out near Burnham on Crouch but since it's been with him, it hasn't missed a beat...

Plugs were changed from those that were on the bike when I got it, to a new set when it had a service recently. And I've metered out the airflow sensor as per the Haynes manual, and it 'seems' to be working - i.e. no shorts/open circuits.

I guess it'll now be a case of changing parts and hoping that the problem gets fixed in the process - probably start with coils and go from there.

Someone did suggest the crank position sensor, but since that's part of the alternator on the SV I think that might be the last thing that gets attention.

Thanks for the advice, all appreciated.