Throttle Bodies and Butterfly Valves

[Moirai]

Hi guys,

Couple of quickie sanity check questions, if I may...

1) Does the synch (or mis-synch) of the butterflies (starter valves) affect the entire rev range?

2) Do the throttle cables only adjust the position of the butterflies, or is there anything else they move?

Cheers,


Mark

[Skids]

Originally Posted by Moirai

Hi guys,

Couple of quickie sanity check questions, if I may...

1) Does the synch (or mis-synch) of the butterflies (starter valves) affect the entire rev range?

2) Do the throttle cables only adjust the position of the butterflies, or is there anything else they move?

Cheers,


Mark

Hi Mark

I can positively answer 1) No, they only affect the first few mm of opening of the butterflies hence it's only low revs that you'll sense any difference, but it is a big difference, though only the Mk1 Cr needs them sync'ing every 4k miles or so, on the Mk2 they are factory set and not adjustable (so my dealer told me).

For 2) I cannot positively say whether they do any more than just open/close the butterflies, but I reckon that's all they do.

[Moirai]

Many thanks for the reply, Skids. 

I should explain that my questions were prompted by the variable level vibration issue that I still have. The reason for asking is that I've noticed a certain pattern to when the vibration level and type change, and that's on throttle changes.

For example; this morning I left home for work and headed through Watford and out to the M1. During this time the vibs were a bit buzzy through the pegs. Nothing bad, but not great either. I get on the M1 and head south for one junction and open her up a bit to around 5k revs. Again, she's a bit buzzy, but nothing more. I reach the next junction, throttle off, change down a coupe of gears as I hit the off ramp, and as I throttle up again, the vibration becomes gritty and rough as if someone has dumped some gravel in the engine. I de-clutch and blip the throttle a few times, shutting it fully each time, and the vibs drop back to their previous buzzy state.

As I say, that's just one example. I've noticed this behaviour quite a bit now, and certainly now that I'm more attuned to it, and it baffles me.

To my mind, it points the finger at some kind of de-syncing going on with the fueling which is causing an inbalance (and hence the vibs), but I'm not clear exactly what would be causing it.

The fact that, as I mentioned in my Vibrations thread, there was I point in my journey down to the New Forest over the Spring Bank Holiday where she suddenly stopped buzzing and became smooth and way more eager and responsive, tends to say to me that there's nothing major wrong. It's just something variable that is going out of wack.

Anyway, I wondered this morning when I got to work whether or not, if the butterflies sync affected the entire rev range, if one of the valve pivots was sticking slightly and causing a lag and mis-position of one valve which was causing the fueling to be out slightly on one cylinder. If it was, maybe opening and closing the throttle was reseting it and causing the change in vibs I am seeing.

Unfortunately, your answer to question one blows that theory out of the water. 

On question two, I suspect the same, and that opening the butterflies is all it does. If it is though, I still stumped over what is causing this behaviour.

HGB changed the plugs a couple of weeks back, which made no difference, and remarked that there were no error codes, current or stored. They don't think there's anything wrong (which they certainly would if they'd felt what she was like on my Bank Holiday trip), so they won't look any further from a warranty perspective.

That leaves me feeling very frustrated. After her Bank Holiday smooth and fast behaviour, I know she can be like that. But I'm struggling to diagnose and narrow down what is causing the buzzy vibs behaviour.

The really annoying thing is that I spent all this money primarily to get away from my old problematic bike and get something that I could use and enjoy, not to acquire another damn problem...

Bah... 

P.S. It's just occurred to me that I may be confusing butterflies and starter valves. Are they different or the same?  If they are different, then my original theory about the butterflies going out of sync may still hold water....

[Skids]

Originally Posted by Moirai

Many thanks for the reply, Skids. 

I should explain that my questions were prompted by the variable level vibration issue that I still have. The reason for asking is that I've noticed a certain pattern to when the vibration level and type change, and that's on throttle changes.

For example; this morning I left home for work and headed through Watford and out to the M1. During this time the vibs were a bit buzzy through the pegs. Nothing bad, but not great either. I get on the M1 and head south for one junction and open her up a bit to around 5k revs. Again, she's a bit buzzy, but nothing more. I reach the next junction, throttle off, change down a coupe of gears as I hit the off ramp, and as I throttle up again, the vibration becomes gritty and rough as if someone has dumped some gravel in the engine. I de-clutch and blip the throttle a few times, shutting it fully each time, and the vibs drop back to their previous buzzy state.

As I say, that's just one example. I've noticed this behaviour quite a bit now, and certainly now that I'm more attuned to it, and it baffles me.

To my mind, it points the finger at some kind of de-syncing going on with the fueling which is causing an inbalance (and hence the vibs), but I'm not clear exactly what would be causing it.

The fact that, as I mentioned in my Vibrations thread, there was I point in my journey down to the New Forest over the Spring Bank Holiday where she suddenly stopped buzzing and became smooth and way more eager and responsive, tends to say to me that there's nothing major wrong. It's just something variable that is going out of wack.

Anyway, I wondered this morning when I got to work whether or not, if the butterflies sync affected the entire rev range, if one of the valve pivots was sticking slightly and causing a lag and mis-position of one valve which was causing the fueling to be out slightly on one cylinder. If it was, maybe opening and closing the throttle was reseting it and causing the change in vibs I am seeing.

Unfortunately, your answer to question one blows that theory out of the water. 

On question two, I suspect the same, and that opening the butterflies is all it does. If it is though, I still stumped over what is causing this behaviour.

HGB changed the plugs a couple of weeks back, which made no difference, and remarked that there were no error codes, current or stored. They don't think there's anything wrong (which they certainly would if they'd felt what she was like on my Bank Holiday trip), so they won't look any further from a warranty perspective.

That leaves me feeling very frustrated. After her Bank Holiday smooth and fast behaviour, I know she can be like that. But I'm struggling to diagnose and narrow down what is causing the buzzy vibs behaviour.

The really annoying thing is that I spent all this money primarily to get away from my old problematic bike and get something that I could use and enjoy, not to acquire another damn problem...

Bah... 

P.S. It's just occurred to me that I may be confusing butterflies and starter valves. Are they different or the same?  If they are different, then my original theory about the butterflies going out of sync may still hold water....

The SV's are not the butterflies, they just adjust the first couple of % of their opening.

For a greater depth of technical knowledge, you might try VFRD. There's a lot of 800F owners (same engine) and a wealth of VFR800 knowledge on there.

[panagos]

I thought your problem got solved.On your previous thread you wrote "I took her into HGB at Ruislip Manor today and got Mike the service manager to take a look"  .What the hell happened there? what did they tell you?

Sorry i just read all your post..Have you ridden any other cross than yours?

[Skids]

Originally Posted by panagos

Sorry i just read all your post..Have you ridden any other cross than yours?

Happy to swap rides if you want to travel up to J10 of the A1.

[CBM]

Originally Posted by Moirai

Many thanks for the reply, Skids. 

HGB changed the plugs a couple of weeks back, which made no difference, and remarked that there were no error codes, current or stored. They don't think there's anything wrong (which they certainly would if they'd felt what she was like on my Bank Holiday trip), so they won't look any further from a warranty perspective.

That leaves me feeling very frustrated. After her Bank Holiday smooth and fast behaviour, I know she can be like that. But I'm struggling to diagnose and narrow down what is causing the buzzy vibs behaviour.

How about taking it to another Honda dealer for a 2nd opinion ?