Slightly Lumpy through Rev Range

[gsbiker]

Just fitted Keihan Headers + Ackrapovic Can and notice it's slightly lumpy through the rev range when accelerating. Even worse with baffles out . I don't take it anywhere near red line probably 7000rpm at the very, very max. I don't think I have a problem but rather a characteristic of the GSA when aftermarket exhaust products are fitted. I've heard of the fuel controllers being changed to smooth this out but I know nothing (as usual) and so would be interested to know if others have similar experience and if any have upgraded their fuel controller thingys.

 

[Deleted account LB]

Just fitted some remus headers to standard pipe and the bike is a lot smoother through the revs and far smoother and stronger pickup from lowdown. Bike has only done 1800 miles so may get smoother still. - Dont think this helps though does it

 

[Fanum]

Two inches of wire with a male spade connector on each end and a bit of trial and error with the connector block that sits in your fuse box.......you won't hurt it

Try searching on 'steptoe link' if you want to read more here

 

[Sgt Bilco]

Paul

I`ve tried to replicate your problem with my bike and it`s smooth all the way through. I`ve fitted a new Keihan end can today and it`s as smooth as a smooth thing with no problems.

The Keihan headers will do away with the slight drop at 5k (as will the Remus) so I`m thinking there must be a fuelling issue with your bike. None of our other customers have suffered this problem and I would run it in to your dealer and ask them just to check it out.

 

[Magwych]

Paul,
it's worth whole trying a throttle position sensor reset.

Disconnect your battery, then reconnect after 10 seconds or so.

Then:
Ignition On, smoothly open and close the throttle to fully open and back 3 times.
Ignition Off, within 30 seconds
Ignition On, within 30 seconds, start , and ride.

Total time : 10 minutes. Including looking for a suitabel screwdriver/ spanner to disconnect the battery.

My thought is that the Lambda sensors are adjusting the fuel maps, more in the lower rev range than the upper. Some of these adjustments are stored semi permanently; I believe it is called "adaptive fuel programming" or similar, the TPS reset erases these, returning to the "base" map.

 

[gsbiker]

Paul,
it's worth whole trying a throttle position sensor reset.

Disconnect your battery, then reconnect after 10 seconds or so.

Then:
Ignition On, smoothly open and close the throttle to fully open and back 3 times.
Ignition Off, within 30 seconds
Ignition On, within 30 seconds, start , and ride.

Total time : 10 minutes. Including looking for a suitabel screwdriver/ spanner to disconnect the battery.

My thought is that the Lambda sensors are adjusting the fuel maps, more in the lower rev range than the upper. Some of these adjustments are stored semi permanently; I believe it is called "adaptive fuel programming" or similar, the TPS reset erases these, returning to the "base" map.

I did think that the computer might be adapting to the change and maybe I need to give it more time? The only way I can explain is that I notice just before 3000rpm a slight flat spot and with the Ackrapovic no baffles it was quiet spluttery higher up in the rev range 4-5000rpm. I will try your suggestion cheers. Went on another longish rideout yesterday and find riding with the new headers and can without top box makes the bike quite brisky.

 

[Deleted account 211025001]

Two inches of wire with a male spade connector on each end and a bit of trial and error with the connector block that sits in your fuse box.......you won't hurt it

Try searching on 'steptoe link' if you want to read more here

Fuse box

What an archaic idea, we're talking cutting edge 1200's here and Canbus.................

Fuse box, I dunno, what ever next.......................

Andres

PS As has been said, the mods should make the engine smoother not rougher. I reckon you've disturbed a connection somewhere when changing over the Lamda sensors - think I'd be going over all the wires and connectors on the underside of the cylinders with a fine tooth combe for starters.

 

[Rong]

I have tried both adapted standard headers with balance pipe and headers with no balance pipe connected to my Y piece and Akra can. The adapted headers with balance pipe gives a smoother ride than headers without and there is less popping and banging on the overrun. I should add that I've also got a blue filter and PC installed.
Now I know that computers can't think, but there is definitely a settling in period over which the characteristics change, generally the noise gets louder / crisper but in both cases the power is delivered smoothly (PC?) and in both cases slow running is still a bit lumpy (PC set too rich for slow running?).
The only real way to check all of this is to put the bike on the local Dyno, which at £25 for an air / fuel run has got to be worth it.