Nowt serious, but some help please...

[Ozz]

So I've previously stated that my GSWC TE is my first bike in 14 years. Having now put 400+ miles on it, I have a few questions which hopefully someone may have answer to.

The bike is brilliant, with neck jerking torque if I'm not careful, but it does seem a bit buzzy. At 70mph, the bars are bit 'tingly'. I was expecting smooth. Is this normal? My last bike was a ZX-7R inline four, so I have no other experience of a twin let alone a boxer to grade it against.

The bike also is quite loud on a closed throttle. On the overrun it does pop and bang quite regularly even with a stock exhaust. Again, do they all do that?

I've a big run out on Fri to the lakes and back to get me up to the running in distance and then its off to Coopers for its service. I might have a quick run on a demonstrator to get a different view, However, does this tally with other peoples experiences of the bike?

 

[Andy_E]

You do get some vibration with boxer engines so that sounds normal - the LC engine is a lot smoother than my old oil-cooled 2008 GS but nowhere near as smooth as an IL4 - consider it added 'character'! Popping and banging on the overrun is also quite normal - enjoy it

 

[Ozz]

Cool. Thanks Andy.

 

[Deleted account 251212001]

Sounds normal to me too. You shouldn't get off still tingling through your hands like on a jap il4 though.

 

[tanneman]

Select 6th gear and ride around at 80. That usually solves the problem .

 

[paul08]

Riding back from Verdun to Cologne, I found that the sweet spot on the Autobahn on the last stretch was 6000rpm. Which was 160kph/100mph.
- the engine was purring along, the buffeting of my helmet from the wind coming over and round the screen was all but non-existent.......

 

[WindyChuffer]

I suspect you are gripping the bars / leaning on them. Use a light touch fella...

 

[Nutty]

I suspect you are gripping the bars / leaning on them. Use a light touch fella...

Yep, a lighter grip will sort the buzzy bars. As for the noise, the stock bike is FAR too quiet!

 

[stever1]

Try a set of grip puupies to sort out the vibes

 

[Usurp66]

What you are describing is quite normal for the WC, although it is smoother than previous versions I find the vibes are higher frequency and can leave the hands a bit tingly if your grip is a little tight. Relax and enjoy the noise.

So I've previously stated that my GSWC TE is my first bike in 14 years. Having now put 400+ miles on it, I have a few questions which hopefully someone may have answer to.

The bike is brilliant, with neck jerking torque if I'm not careful, but it does seem a bit buzzy. At 70mph, the bars are bit 'tingly'. I was expecting smooth. Is this normal? My last bike was a ZX-7R inline four, so I have no other experience of a twin let alone a boxer to grade it against.

The bike also is quite loud on a closed throttle. On the overrun it does pop and bang quite regularly even with a stock exhaust. Again, do they all do that?

I've a big run out on Fri to the lakes and back to get me up to the running in distance and then its off to Coopers for its service. I might have a quick run on a demonstrator to get a different view, However, does this tally with other peoples experiences of the bike?

 

[Deleted account 251212001]

Yep, a lighter grip will sort the buzzy bars. As for the noise, the stock bike is FAR too quiet!

Mine aint, its very noisy in the upper rev range wringing its neck. Sounds lovely tbh.

 

[Nick V]

The bike is brilliant, with neck jerking torque if I'm not careful, but it does seem a bit buzzy. At 70mph, the bars are bit 'tingly'. I was expecting smooth. Is this normal? My last bike was a ZX-7R inline four, so I have no other experience of a twin let alone a boxer to grade it against.

I second what everyone else has said so far.
Boxer twins have near-perfect primary balance, but there is always a bit of secondary vibration. Not much you can do.
It's odd... if I were climbing onto an inline four at this stage, I'd probably be a bit unnerved by the lack of vibes!

The bike also is quite loud on a closed throttle. On the overrun it does pop and bang quite regularly even with a stock exhaust. Again, do they all do that?

I think I'm safe in saying Yes. On a closed throttle, under some circumstances, the engine is pulling through a lot of air with no fuel. This can raise the temperature of the cat to the point where it starts being damaged. To avoid this, the ECU might occasionally dump some fuel.
As a rule of thumb: richer mixture = lower temperatures, and vice versa.

 

[Ozz]

Thanks everyone. That's put a few issues to bed. I have noticed another thread which mentions something that I've noticed - hunting. At about 20-35 I can feel the bike hunting in the revs. Its not a huge issue only mildly annoying tbh. I take it that this is a FI and ECU issue. I'll have a chat with the dealer.

 

[Roymondo]

How is drawing fresh air through with no fuel going to raise the temperature of the cat? How is the ECU going to measure this allegedly raised temperature anyway?

 

[Myke Rocks]

Not quite correct.

Boxer twins have near-perfect primary balance, but there is always a bit of secondary vibration. Not much you can do.

A flat twin has perfect primary and secondary balance. With the offset crank, it does, though, have a rocking couple.
If you wish to see a rocking couple in action, get a pushbike and take the chain off the front sprocket. Stand the bike upside down, and spin the cranks hard. The rocking couple will toss the bike about.
Now a rocking couple is very easy to cancel out completely, but it takes two balance shafts to do so. BMW's "engineers" decided they could do it with one balance shaft down the centre of the cam drive shaft. Since there is only one balance shaft, it doesn't work particaularly well. It quarters the amplitude of the vibration, and multiplies the frequency by four.
Hope this enlightens you.
Myke

 

[Nick V]

How is drawing fresh air through with no fuel going to raise the temperature of the cat? How is the ECU going to measure this allegedly raised temperature anyway?

Apologies - I wrote that while something else was on my mind.

I was mistaken in saying 'No fuel': I should have said 'The limited amount of fuel needed to prevent the engine from generating too much engine braking on a closed throttle at higher revs'. That limited amount of fuel is going to result in a much leaner mixture, and that's what raises the cat temperature.

The ECU wouldn't 'measure' cat temperature without a temperature sensor or thermocouple - which the LC doesn't have.
It would, however, be able to detect conditions under which cat temperature might rise to damaging levels (for example, where the following conditions exist):

• Engine revs above a given limit.
• Vehicle speed above a given limit.
• Closed throttle.

At which point, the engine map might dictate that the engine receive X amount of fuel above stoichometric, even though the throttle is fully closed.

A flat twin has perfect primary and secondary balance. With the offset crank, it does, though, have a rocking couple.
If you wish to see a rocking couple in action, get a pushbike and take the chain off the front sprocket. Stand the bike upside down, and spin the cranks hard. The rocking couple will toss the bike about.
Now a rocking couple is very easy to cancel out completely, but it takes two balance shafts to do so. BMW's "engineers" decided they could do it with one balance shaft down the centre of the cam drive shaft. Since there is only one balance shaft, it doesn't work particaularly well. It quarters the amplitude of the vibration, and multiplies the frequency by four.
Hope this enlightens you.
Myke

Quarters the amplitude and multiplies the frequency by four... hence what's described as the 'buzz', I'm guessing?
A better explanation than I could manage. Thanks!
There are times I regret not studying mechanical engineering... blame my terminal need to rebel as a teenager. One of my riding buddies has always been a fan of Triumphs (he currently rides a Tiger Explorer) and I had quite a time trying to explain the concept of the 'rocking' vibration that necessitates a balance shaft on an inline triple with a 120-degree crank.

 

[shortywilliam]

I thought that the main use of the cruise control was so you could take either hand off the bars and beat some life back into it after it has gone numb with the vibration's.
But I suppose that finding a sweet spot will do also.

 

[Ozz]

On a completely separate note (but not wanting to open a new thread), While giving the bike a thorough wash I noticed that whoever had painted the beak (in my case Alpine White) appears to have completely given up when it came to the underside. I get that the other panels reverse sides are hidden, as they're flush against the bike, but the beak isn't. Is it just mine or is it a standard thing for BMW to do on a 14k bike?

 

[GSMartin]

On a completely separate note (but not wanting to open a new thread), While giving the bike a thorough wash I noticed that whoever had painted the beak (in my case Alpine White) appears to have completely given up when it came to the underside. I get that the other panels reverse sides are hidden, as they're flush against the bike, but the beak isn't. Is it just mine or is it a standard thing for BMW to do on a 14k bike?

Mine is just the same