Please humour a Newbie - advise required

[NigelM]

I have has the GSA for a month now. 1000 miles down the road and I'm loving it. Its a 2012 Hexhead.

Now I'm a bit of a geek for getting things just right. Whether it's bikes, cars, boats, guns, whatever, I like to get the best from them and I hate things that have been "detuned" to comply with some bullshit European regulations.

Reading the threads on here in a bit of detail it seems that BMW have done 3 main things to comply with emission and sound regulations.

1. Catalytic converter which is not required on a bike in the UK.
2. Detune on the engine map, especially around 4000/5000 rpm and a very lean AFR across the rev range.
3. Fitted some flappy valve thing to reduce noise at the tested 4500 rpm level. Flappy valves are also prone to seizure.

The lean running especially makes the bikes prone to issues with valves as they get older and to prolong the engines life you want to get the AFR closer to 13.5 than 15.

The established "fix" to this little lot seems to be to fit a new set of de cat headers that also bypass the flappy valve and take the bike to Hilltop for a re map. This makes the bike significantly nicer to ride and much more responsive.

Have I missed anything or do I seem to be on the right track?

Advise please.

Thanks, Nigel

 

[Norfolk Tiger]

You've got it spot on in my opinion as what you've listed is what I've done to mine

 

[Boxerfan]

And I just happen to of removed the decat headers,spacer to eliminate flappy thing, and a Remus carbon hexacone exhaust, from my 13 plate Hexhead, PM me if your interested Nigel. I'm going to put them up for sale here in the next few days anyway.
Cheers,
Steve

 

[NigelM]

You've got it spot on in my opinion as what you've listed is what I've done to mine

Are you happy with it?

Am I missing anything?

I was looking at the Keihan headers with the flappy bypass. Anything wrong with that decision?

Thanks for the help.

 

[Boxerfan]

And I just happen to of removed the decat headers,spacer to eliminate flappy thing, and a Remus carbon hexacone exhaust, from my 13 plate Hexhead, PM me if your interested Nigel. I'm going to put them up for sale here in the next few days anyway.
Cheers,
Steve

 

[Norfolk Tiger]

Are you happy with it?

Am I missing anything?

I was looking at the Keihan headers with the flappy bypass. Anything wrong with that decision?

Thanks for the help.

Very pleased with it my reasoning for going the route I did was to end up with a much smoother bike. If you haven't done so already have a read of the various hilltop threads and you'll struggle to find anyone who hasn't been pleased after a visit. I've got the akra headers on mine however the Keihan headers look good from what I've seen on a recent group buy thread.

 

[Greenman14]

Just fitted Keihan headers, removed the flappy valve and had a Hilltop remap. It's a different bike, actually feels quick, especially above 5000 revs. With the remap alone it was smoother than standard but fitting the headers has made it a little rougher from 4000 to 5000 revs. I think they're all like that, though some are worse than others. Received wisdom is that changing the end can makes no difference to the performance, same goes for a non-OEM air filter. Mine certainly sounds better with the Keihan headers.

 

[NigelM]

Just fitted Keihan headers, removed the flappy valve and had a Hilltop remap. It's a different bike, actually feels quick, especially above 5000 revs. With the remap alone it was smoother than standard but fitting the headers has made it a little rougher from 4000 to 5000 revs. I think they're all like that, though some are worse than others. Received wisdom is that changing the end can makes no difference to the performance, same goes for a non-OEM air filter. Mine certainly sounds better with the Keihan headers.

It sounds as if you had the remap first and then fitted the new headers? Would that account for the roughness or have I got it wrong?

 

[Betty Swollocks]

Flappy valve removed from my 2010 TC and over the winter I had the cat removed from the original pipework..... Bike revs a lot freer and is much more fun to ride.

Getting the remap done in 10 days time just to set everything up and I can't wait!

 

[DervMan]

Flappy valve removed from my 2010 TC and over the winter I had the cat removed from the original pipework..... Bike revs a lot freer and is much more fun to ride.

Getting the remap done in 10 days time just to set everything up and I can't wait!

How did you remove the cat innards?

 

[Bendy toy]

Cut & weld is the usual way. Take the innards to a scrap metal dealer. Unless you can weld it yourself, you can get a used header for not much more money.

 

[TimboLeMatelot]

The low down rough running may be due to having removed the flap valve. I believe it's purpose to be unrelated to noise control and more to do with exhaust back pressure with smooths out the peaks and troughs in the gas flow.

 

[sagalout]

I originally went for Akro headers and end pipe, with a power commander. Didn't like the Akro headers due to the poor fitting so switched to the keihan headers and Akro end pipe. This fuelled really well on the dyno, but found the Akro end pipe a bit loud, so have had another dyno run with standard pipe, which I will use for touring. Whilst there is only 4bhp in it between the Akro and standard end pipe, there is a noticeable dip in the torque and perceived roughness at about 4k. The tuner said its a characteristic of the pipe and header combination and can't be tuned out.

 

[NigelM]

I originally went for Akro headers and end pipe, with a power commander. Didn't like the Akro headers due to the poor fitting so switched to the keihan headers and Akro end pipe. This fuelled really well on the dyno, but found the Akro end pipe a bit loud, so have had another dyno run with standard pipe, which I will use for touring. Whilst there is only 4bhp in it between the Akro and standard end pipe, there is a noticeable dip in the torque and perceived roughness at about 4k. The tuner said its a characteristic of the pipe and header combination and can't be tuned out.

That's really interesting.

Which model is it? Single cam, Twin cam or LC?

Presume you have bypassed the flappy valve thingy as well?

The simple change from Akro can to Std can gives significantly rougher running around 4000 rpm and 4bhp less.

Could you not have added baffles to the Akro to reduce the noise?

Which tuner did you use.

Sorry for all the questions but I'm keen to get it right first time if possible.

Thanks,

Nigel

 

[sagalout]

2012 Twin Cam.

With the baffle in there's an annoying rattle so I took it out and the rattle went - just noisier. It was fine in normal use, but a bit droning on the motorway.

I used Daytuner at Killinghall, near Harrogate. He knows what he's talking about - background in race bikes including the a TT team and a garage full of racing cars and bikes! He said it was to do with the back pressure caused by the stock can. The BHP difference is negligible but the torque curve actually dips and that's what you feel, whereas with the Akro it just flattens a bit.

I have a dilemma now, as the bike definitely runs better with the Akro pipe, both on a dyno and in the real world. I may experiment with trying to rid the Akro of the baffle rattle!

If you go for the keihan header get the version with the welded link pipe - it looks much neater. I already had the nippy Normans link pipe and it's fine but not as tidy.

 

[sagalout]

I should also say it's 6 months since I've ridden the bike stock - I think that dip was there in the original setup too, I've just got used to the free flowing system and power

 

[NigelM]

2012 Twin Cam.

With the baffle in there's an annoying rattle so I took it out and the rattle went - just noisier. It was fine in normal use, but a bit droning on the motorway.

I used Daytuner at Killinghall, near Harrogate. He knows what he's talking about - background in race bikes including the a TT team and a garage full of racing cars and bikes! He said it was to do with the back pressure caused by the stock can. The BHP difference is negligible but the torque curve actually dips and that's what you feel, whereas with the Akro it just flattens a bit.

I have a dilemma now, as the bike definitely runs better with the Akro pipe, both on a dyno and in the real world. I may experiment with trying to rid the Akro of the baffle rattle!

If you go for the keihan header get the version with the welded link pipe - it looks much neater. I already had the nippy Normans link pipe and it's fine but not as tidy.

Your bike is exactly the same as mine, 2012 Twin Cam, which makes this all the more interesting.

Thanks very much for your help.

Nigel

 

[DGB]

And I just happen to of removed the decat headers,spacer to eliminate flappy thing, and a Remus carbon hexacone exhaust, from my 13 plate Hexhead, PM me if your interested Nigel. I'm going to put them up for sale here in the next few days anyway.
Cheers,
Steve

You have PM

 

[Bendy toy]

They all have a power dip around 4000rpm. The PC helps to improve this but the only sure fix is a remap.
I have an Akraprovic stacked silencer in titanium. I agree the header pipe fit isn't perfectly symmetrical but it takes an expert to see it.
It's VERY loud without baffles but definitely quicker on the bum cheek dyno than a standard can with Remus decat headers.
I've fitted straight 30mm baffles on spacers which take it to similar noise levels to the decated standard can. 47mm baffles are quiet but just bung it up and miss the point. The noise on mine is more pipey and less growly than standard.
I'd love a pair of flappy baffles to choose the noise on the fly.