Fluctuating Revs

[topcat2006]

Bl$$dy Bike!

If I open the throttle to 2000 rpm (or any rpm) and keep the throttle constant, in neutral on the centre stand the revs vary 200 rpm up and down of 2000 rpm. Its slow fluctuating every 20-30 seconds or so.

Any ideas. Throttle cables - but then surely it'd be in one direction?

Oh and for a while now I have had bad vibes too - had a throttle body balance done a while ago and didn't really make a difference.

Coil pack? or anything else?

Thanks

Tom

 

[Womble]

Uneven idling sounds like a dicky lambda sensor. They're easy to check if you have the right kit - have you got a friendly injection specialist nearby?

 

[topcat2006]

No, no-one near. Are they dear? might just be easier to swap it anyway.

 

[Womble]

Diagnosis through substitution can get a bit expensive. There must be some local auto electricians who could check it out for you - all you need to do is to check the voltage on the back of a connector, it's just that it's better done with an oscilloscope, not a multimeter.

 

[topcat2006]

Who needs an auto electrician for that?! I have a scope at work so there must be a procedure somewhere for testing it?

I know, I know "Search" is my friend.....

Thanks

Tom

 

[topcat2006]

One thing - you said uneven idle - I'm seeing the fluctuation at any revs?

Thanks

Tom

 

[Womble]

The lambda sensor is used at relatively low throttle openings, under about 2500 RPM (from memory) and when on a relatively steady throttle. If accellerating or at high revs, the sensor isn't used - does that sound about right?

Please don't rule out other causes, it could still be a coil stick or a Hall sensor.

 

[topcat2006]

Just been in the garage tinkering!

Pulled off the bottom spark plug caps and when the l/h side one ws pulled off the idle speed slowed down a touch and then sped up again when refitted. When I pulled the r/h side one off the idle was unchanged.

Therefore it looks to me as they are degrading. I think I am going to order a pair in the morning and fit these as a start. My experience with electronics says that if one is breaking down the other can't be far behind it!

Will still test the lambda sensor - I think if I read it right I can try unplugging it temporarily and seeing how it runs after that.

Thanks for the tips!

Tom

 

[davegs]

Sounds like a stick coil are beginning to fail

 

[topcat2006]

Well, the saga goes on.

Have replaced the stick coils and the spark plugs tonight. The primary plug on the l/h cylinder was loose (and looked to have been for a while as the sealing face of the washer was rusty)!

The bike is now idling properly and also holding revs without fluctuating.

Its still rough though. Not rough as in when you seat the throttle cables wrong when moved the fuel tank (Have done this.....) but it still is not smooth.

I've sprayed some easy start round all of the joints on the throttle bodies and the port for balancing the bodies and no rise in revs and all the rubbers look good too.

Have set the tps sensor voltage to 0.38v and pulled fuse 5 and done full thottle 3 times.

I'm going to borrow a scope from work tomorrow and check the lambda sensor. Thought I might as well do that as it looks as thought the connector is under the fuel tank anyway.

Oh - fuel tank. The fuel pump is making a funny "wooshing" noise when you turn the ignition on. It sounds as though it is pumping fuel into the tank. I've never noticed it do this before. So I guess next step to check is the breather.

I've also noticed that with the clutch out, in neutral the g box is noisy and very "clonky" if you put it into gear. The noise stops as soon as you pull the clutch lever. Now I'm sure this has always been the case but Im just wondering - if a gearbox input bearing was on ts way out could that affect the smoothness of the engine?

Not sure where else to go really. I spoke with BVM today and they have offered to ride it if I bring it in and let me ride another GSA to compare - might take them up on this and at least this way I will know if it is just me or not!

One thing is sure - I'm getting really down about this. ` i love the bike but at the moment I am hating riding it. After 10 miles I can't feel the controls due to the rough running. I feel like selling it I really do.

Tom

 

[Carl]

The lambda sensor is used at relatively low throttle openings, under about 2500 RPM (from memory) and when on a relatively steady throttle. If accellerating or at high revs, the sensor isn't used - does that sound about right?

Please don't rule out other causes, it could still be a coil stick or a Hall sensor.

Also... I dont think the lambda cuts in until a predetermined temperature, I may be wrong. The bike will still run with it disconnected if that helps fault find

 

[topcat2006]

Checked the lambda sensor tonight, it is cycling correctly if a little slow. Its taking up 3 seconds to do a cycle. I've tried disconnecting it but doesn't seem to make much difference.

I spoke with BVM today and they are going to have it all day on Monday and I'm going to have a 1200GSA for the day. (they don't have any 1150's) It will be interesting to compare the two and they are all going to ride mine and see what they think.

Tom

 

[davegs]

Bike loan day!

I can see another loss to the 1200 postings comming up!

 

[illustratedman]

Rough running

Do the test on the coils, remove the bottom plug leads with the bike running one at a time and see if it gets worse or cuts out.

 

[skywalker]

Get the bike up to operating tempreture and allow it to idle. Get some wd40 or brake cleaner & spray the rubber inlet manifolds where they bolt to the head.
£5 says tickover will either falter or increase depending on what you use and it'll be on the left side.
Replace the manifold as it will have become porous. Do't try and reseal it cos it won't work
Check the fuel pump snap connectors haven't worked loose

 

[Womble]

Do the test on the coils, remove the bottom plug leads with the bike running one at a time and see if it gets worse or cuts out.

But he's changed the sticks already and it hasn't (fully) fixed the problem

 

[topcat2006]

But he's changed the sticks already and it hasn't (fully) fixed the problem

It has in that it is idling smoother when you remove the l/h side - where as before the idle would slow down.

Get the bike up to operating tempreture and allow it to idle. Get some wd40 or brake cleaner & spray the rubber inlet manifolds where they bolt to the head.
£5 says tickover will either falter or increase depending on what you use and it'll be on the left side.
Replace the manifold as it will have become porous. Do't try and reseal it cos it won't work
Check the fuel pump snap connectors haven't worked loose

Done that with easy start and no change! Visually the rubber are not perished either. Can I have the £5 please - it might help pay any bill that is coming up.

I can see another loss to the 1200 postings comming up!

Only if it is a bloody good deal and a hell of a lot better than the 1150 as I love the bike and I don't really want to get rid of it but at least I will have a comparison.

It goes to BVM Moto in the morning so it will be interesting to see what is found. It's either going to be something costly or something really stupid which I have missed methinks!

Tom

 

[warmshed]

You mentioned the "wooshing" sound coming from the pump, sounds like a leak from the filter, this would cause rough running, had that, done that, day before a continental trip!!

 

[topcat2006]

I did wonder that but it has stopped now and I get just the normal pump running sound no more wooshing!

 

[topcat2006]

Well Mike at BVM had a good ride and tinker today and his verdict:

One of the smoother 1150GSA's he has had. TBH as soon as I jumped on the 1200 GSA I did think that was going to be the case.

Ah well at least I know there is nothing "wrong" with my bike and it's just me....

Thanks all for your suggestions and help.

Tom