Bonneville America Forums Forums Technical Forums Performance Mods Poor running after swapping exhausts.

Hi all, finally back on a 2015 Speedmaster. Not being one to leave things alone for long, I've started the usual mods but have run into problems. This is my first EFI bike.

Today I:

Removed the O2 sensors, using a kit that came with resistor fitted connector blanking plugs.

Removed the AI system

Swapped the standard exhausts for short 19 inch turnouts.

There are no mods to the standard airbox

I started the bike and let it run for 20 minutes without touching the throttle as advised.

Went out for a ride. OK at first but the bike is stuttering a bit. As I rev up, it stutters and then seems to clear and run normally on til I hit the next gear and then repeats for each gear.

Is this a symptom of lean running. I haven't remapped yet as I was hoping not to until I can afford the airbox removal. Or is this a problem with either the AI or O2 removal. Thanks in advance for the help

There is wisdom in the advice of only making one modification at a time and seeing the results before you move on to the next.

Yep, realise that, but the O2 sensor and AI removal, should have little or no effect on mid range. It seems to be a pretty standard mod to reduce low rev flutuations in fuel mix and reduce popping from unburnt fuel.

Looks like I might have to put the original exhausts back on until I can get the correct map. I had hoped to avoid the cost until I could afford to remove the airbox.

it's likely that now with the new exhaust, you are running lean.

I have a 14 America. and havent lost anything with new pipes wonder if its the o2 sensors

what pipes did you swap to?

Swapped to short 19 inch turnouts

Sounds like a job for the Pieman.

A twin power map from the pieman was the plan, but at £90 a time, I was hoping to hold off until I've enough money to do any airbox mods first so I only have to pay out once.

Dave is right. TORs don't even need any carb adjustment after you put them on because they are nearly as restrictive as the stock pipes.

If you have disconnected the 02 sencors, you should also uncheck the 02 sensor box with Tune ECU to see if that changes things. If you don't have the cable and program then I would suggest reinstalling the 02 sensors with the new exhaust and see if things improve. Then you know where to start from.

you need tune ecu but if it were me i would put a power commander in it. JMO

The kit for the O2 removal has blanking plugs for the wiring harness fitted with resistors which should (I believe ) make the ecu think the emissions unburnt fuel to air ratio is constant and stop the ecu from tweaking the fuel mix. Just bought ecutune but the cable hasn't arrived yet.

The odd thing is, the first ride over to a friends (about 3 miles) was brilliant. No low rev jerkyness to the throttle. Nice pull on acceleration and no stutter. Stopped off for 15 minutes, restarted the bike and started stuttering before I reached the end of his road

Update, took her out again. Stuttering only happens at about 3500 rpm if I'm accelerating aggressively (situation normal). If I'm really slow and steady on the throttle, no stutter. Checked the breather hose to make sure it wasn't kinked. Tightened everything up. Everything looks good, so it would seem to be fuel starvation from lean running. Will get the ecutune lead sorted. Struggling to find a map for any tunes that don't include airbox mods, so any suggestions or members with a map they can send me would be muck appreciated as a temporary fix till I can afford a twin tune map. Cheers All for the advice

I had to rejet for some of the early short slashcut TOR s as well. The later ones, what was/is their purpose, a different exhaust note maybe?

Things went horribly wrong today. On the way to work, it was very cold and the bike ran like a dream, no stutter. On the way home, quite warm, got half way home and the bike started Sutter in all the time. Had to nurse her home. Couldn't open the throttle at all without terrible stutter. Even with the throttle held in a steady position. Pulled up outside the house and the idle, runs for a bit, then races for a couple of seconds then drops back to normal. Any suggestions?

Unfortunately, my speedy is 2015 so fuel injected. Clearly it's running lean. I'm unable to find a tuneecu map for the turnout exhausts on such a new bike. Was hoping a member might have a hex file I can load

Unfortunately mines a 2015 Speedy. Clearly it's running lean and needs remapping. Im struggling to find a tuneecu map for the setup I've got on such a recent bike and was hoping a member might have a hex file I can use.

You're making me appreciate my carbs more and more.

Oh for a good old fashioned pair of carbs

Problem sorted, whilst yanking cables on Saturday I'd inadvertently loosened the connector to on of the coils. Must have come off on the ride home last night. Plugged in ecutune and it came up with the fault code straight away'coil 2 circuit' saved me a lot of hunting around. Fantastic bit of free software. Remapping now