Constant throttle: strange effects

[demito]

Hi all,
don't know what to think of this but since my last service (10000kms) I have had some problems with the bike.

1. Engine running "heavier": did a TBsynch with a carbtune. Slightly better, not as before. At idle: seems to miss a beat every now and then.

2. at constant throttle, lower speeds (up till 80 kmh), the bike bounces a bit. Seems like the engine is not delivering constant power. Not terrible but noticeable enough to let me first think it was a suspension problem due to heavy loads on the bike (10 kg each side, mmmh heavy?)

Read some posts on surging but don't know exactly what it feels like. Could this be it? Could it have to do with valves not properly adjusted? Mechanic said TB synch and valve adjustment were done...

I don't want to fiddle around too much with the valves if not necessary though.

Oh yes, it's a 2004 1150 GS adv

Tnx for the feedback

Demito

 

[MikeO]

Sounds like it might be surging.

I can best describe surging as being unable to keep a constant speed smoothly. On my bike it happened at around 3000rpm (30mph in 3rd, 40mph in 4th). At a fixed throttle setting, the bike would always be accelerating or decelerating - it would never 'cruise'.

Mike

Edit - just seen your edit - I don't think I've heard of any cases of twinsparks (which I assume yours is, from it's build date) surging...

 

[demito]

Sounds like it might be surging.

I can best describe surging as being unable to keep a constant speed smoothly. On my bike it happened at around 3000rpm (30mph in 3rd, 40mph in 4th). At a fixed throttle setting, the bike would always be accelerating or decelerating - it would never 'cruise'.

Mike

Edit - just seen your edit - I don't think I've heard of any cases of twinsparks (which I assume yours is, from it's build date) surging...

Indeed it's a twin spark. But it drives me crazy. It ran soooo smoothly until that 10000 km service. It is not horrible but I want my bike back as before.

By the way, it's not really noticeable at the rev display or speedo. But a bike that bounces on a perfectly flat surface at constant throttle is not normal I think. Nothing with the tyres either (checked them). Also carbtune indicates balanced at constant revs but unbalanced when revving up and down.

Any similar experiences?

I think I might check the valves anyway.
Not being a tech guy , there's always an opportunity to learn.

 

[MikeO]

No indication on the tacho - just a surging/hunting when trying to maintain a set speed. Not sure what you mean by 'bouncing' though...

Mike

 

[demito]

No indication on the tacho - just a surging/hunting when trying to maintain a set speed. Not sure what you mean by 'bouncing' though...

Mike

The lack of constant power makes the bike like jumping back and forth while riding. This has a bouncy effect. Its like riding on an uneven surface while it's perfectly flat. (No, it's not like an off road experience on the highway )

Cheers

Demito

 

[MikeO]

It's surging.

First I've heard of in a twinsparker. The first place I'd look (especially as it has just been serviced) is poorly adjusted valve settings and/or throttle body synch.

Can you take it back to the dealer and get them to re-do it?

Mike

 

[demito]

It's surging.

Can you take it back to the dealer and get them to re-do it?

Mike

Done that. They fiddled around with the air filter that was not placed correctly and stated that should solve the prob. Since I work long days it is quite difficult for me to get there so I decided to start learning to work on the bike anyway. The mechanic couldn't "reproduce" the problem. Yeah right...

Tnx for the info mate

Cheers

Demito

 

[demito]

Just another info. Valve adjustment, should that be done on a perfectly cold engine?

 

[MikeO]

Steptoe posted that he may have found the cure to surging here , although he doesn't specify what the cure might be...

Mike

 

[MikeO]

Just another info. Valve adjustment, should that be done on a perfectly cold engine?

Yes.

Mike

 

[turbine_2]

It's worth checking that all 4 spark plugs are okay. If there's one not firing properly then that will make it run like you're talking about.

 

[MikeO]

It's worth checking that all 4 spark plugs are okay. If there's one not firing properly then that will make it run like you're talking about.

Good call.

If you've not adjusted the valves before, this will guide you...

Mike

 

[demito]

Steptoe posted that he may have found the cure to surging here , although he doesn't specify what the cure might be...

Mike

Yeah, read it as well.

I have the solution how to seduce extremely beautiful women and making them extremely horny.
I have learnt that the hard way so now it's up to you guys

Steptoe: shall we exchange tricks

Cheers

Demito

 

[demito]

It's worth checking that all 4 spark plugs are okay. If there's one not firing properly then that will make it run like you're talking about.

2 questions here:

1. How to check this? By replacing them?
2. What is the torque setting for both the Spark plugs?

Tnx mate

Cheers

Demito

 

[Steptoe]

The second spark plug doesn't fire over 3K revs - it's just to clean up the emmissions -

And twin sparks can surge -


and they can be cured

 

[(RIP) Kaister]

Surging is the same as 'hunting'.

It needs richening up slightly .

 

[Fanum]

While you're checking the spark plugs, check also the leads that go onto them that contain coils.

Mine started breaking down (well, one was bulging and had rust appearing at a seam...it looked like in some very odd wway my cylinders might have become immersed in water ) and I lost power, there was rough running, hesitation etc etc.....I wouldn't have described it as bouncing but otherwise sounds similar.

That nice Mr Tippytoes lent me a pair from another Adv and I've had mine replaced under warrenty (Twin spark Adv)

Now if I could only work out where all this water's coming from

 

[turbine_2]

The second spark plug doesn't fire over 3K revs - it's just to clean up the emmissions -

It doesn't? Interesting.

 

[turbine_2]

2 questions here:

1. How to check this? By replacing them?
2. What is the torque setting for both the Spark plugs?

Tnx mate

Cheers

Demito

You may be able to tell by looking at their condition. With mine it was very obvious that there was something wrong. Substitution may not do the trick as it may be the coils or HT leads that are at fault.

I don't know the torque settings I'm afraid.