Suddenly sluggish

[Red ones]

My SK8 has decided it wants to be rather sluggish. I don't think it is just the cold that has done it. It seems like the engine has a shed load more resistance to it. The fuel consumption has dropped from 60mpg to about 54mpg. But I can't put a finger on it.

Brakes don't appear to be dragging although they could do with new seals soon. The wheel bearings aren't getting hot. I just can't put my fonger on it.

New air filter not long ago, checked the plugs only a few weeks ago.

THe only thing I think needed soon is a clutch lifter - but that doesn't explain it.

[Craig380]

Has there been any change in the way it starts or ticks over? It's unlikely, but could something have got stuck in, or near, the intake snorkel for the airbox? One or more of the spark plugs couldn't have loosened off a little after being checked?

You mention the brakes don't seem to be dragging, have you felt the discs (both front and rear) immediately after a ride to see if they are unduly warm?

If that all checks out, it might be worth chucking some injector cleaner in the tank.

[Bibio]

You mention the brakes don't seem to be dragging, have you felt the discs (both front and rear) immediately after a ride to see if they are unduly warm?


dont stick your fingers on it.. spit on the disc and if the spit fizzles or dries up quickly then its too hot.

[Red ones]

Definitely not brakes dragging. The discs are not hot. From experience when brakes drag they start binding at higher speeds.
I got the thermographic camera on the bike after a long run, nothing unusually hot. (I'm a flash so and so, what with the camera!)

Good point about plugs coming loose. I'll check this weekend.
Time to fill the tank tomorrow, so I'll see if I have additive in the garage.

I'll probably check the air box too, but seems a long shot.

[Biker Biggles]

Might be worth pulling the plugs out when you check if they are loose. They will tell you if it is running rich or lean which could be the issue. You say it had a new airfilter recently. Was it seated properly and standard spec? OE Suzuki or pattern? All pipework/ breathers still in place?

[Red ones]

As luck has it I'm unable to go to work today, so Ive had an hour or so working on it.

The airbox had one screw that I had forgotten to screw down, but I would have thought that unlikely to cause the issue. The plugs look OK, one was easier to undo than the other 3, but even that wasn't loose.
I've taken the opportunity to tighten the chain, and had a look around for any loose hoses but couldn't find any that I could reach at least.

I popped a battery tester on which showed 100% charge before I turned the key, as soon as I turned the key to switch the ignition on the test showed a poor battery. This was strange as the engine started perfectly. Its an 8 yo glass mat battery, but the optimate never reports a problem with it.

When I put the bike back in the garage it seemed alright, but I guess I shall only find out when I go back to my commute. As a precaution I put the diagnostic tool in, but again its showing nothing unusual at the moment, even the TPS is bang on.

[Biker Biggles]

My bet is it cures itself with a new tank of fuel and some nicer weather.

[SV650rules]

A battery that is on the way out can cause all sorts of unexpected problems - I post on a Honda Jazz forum and people have cured such diverse problems as loss of engine power, electric power steering playing up, radios losing stations and mysterious misfires by investing in a new battery, if the battery showed bad by just turning ignition on it may be a good warning, an 8 year old battery has paid its dues, even Yuasa batteries have to be replaced at some time.

[maviczap]

As luck has it I'm unable to go to work today, so Ive had an hour or so working on it.

The airbox had one screw that I had forgotten to screw down, but I would have thought that unlikely to cause the issue. The plugs look OK, one was easier to undo than the other 3, but even that wasn't loose.
I've taken the opportunity to tighten the chain, and had a look around for any loose hoses but couldn't find any that I could reach at least.

I popped a battery tester on which showed 100% charge before I turned the key, as soon as I turned the key to switch the ignition on the test showed a poor battery. This was strange as the engine started perfectly. Its an 8 yo glass mat battery, but the optimate never reports a problem with it.

When I put the bike back in the garage it seemed alright, but I guess I shall only find out when I go back to my commute. As a precaution I put the diagnostic tool in, but again its showing nothing unusual at the moment, even the TPS is bang on.

Maybe part of the battery is fubarred and it's on the way out, this cold snap is an ideal recipie for killing a battery. Which is causing the issue

[Red ones]

Well tomorrow is the first day I have to ride it since I worked in it.
Hope it's sorted!

[garynortheast]

Any update on this? How is it running now?

[Red ones]

Yesterday it was generally better, although a couple of times it seemed to go back to being sluggish. I started wondering if one of the coils is on its way out, but there is no point trying to diagnose that until it falls completely otherwise I'm chasing an intermittent fault like a fool.

Today it behaved.

I will have another 60 miles on it tomorrow then will refuel again and see how it goes. I'll pop some Winns DryFuel in just to get any condensation out of the tank.

Fuel consumption used to be 60mpg, it's dropped to 52-54 in the last couple of months. Is consumption doesn't pick up in planning to get the throttle bodies rebalanced and replace the plugs as a precaution.

[Red ones]

The first tank was 60mpg and performance normal. The second was 56mpg but Sharon performance was good, but I think I overfilled the tank.

Seems to be OK on performance now. Just the brakes are now playing up (see my other thread)