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Thinking about adding an auxiliary ECU

belrix

Well-Known Member
Gold Rider
Nov 2, 2015
381
194
158
49
SouthEast Kansas
I've been kicking around the idea of adding a RapidBike auxiliary ECU to my '17 AT and adding a few other bits to hopefully increase the HP and torque a little bit.

Full disclosure: I understand the gains will be minimal and most likely not worth the expensive, but I ran a tuner with a few performance bits on my Dodge Challenger and liked it, my 'butt-dyno' said it was worth it. :)


I am planning on adding the following:

RapidBike EVO ECU
Yoshimura RS-4 muffler
K&N air filters


Anything else I should add to the list?

Thanks!

Brian
 

Graves

Moderator
Staff member
Legendary Rider
Aug 14, 2016
1,119
349
143
So. Cal.
Try a full exhaust (exhaust less the cat), K&N's and drill the air filter cover lids, or remove the snorkels and open the holes. I'll bet this will add as much as any re-flashed PCM.

Years ago I had a VTX1800C. Everybody was using power commanders and aftermarket exhaust, those bikes were faster. I opted for a simple slip on can muffler, K&N and completely gutted the air box inlet, they were no longer able to pull away from me. The problem with the VTX, and presumably our AT's, is that with such big cylinders the intake and exhaust have to breathe, opening up both helps more than you can imagine.

I've been kicking around the idea of adding a RapidBike auxiliary ECU to my '17 AT and adding a few other bits to hopefully increase the HP and torque a little bit.

Full disclosure: I understand the gains will be minimal and most likely not worth the expensive, but I ran a tuner with a few performance bits on my Dodge Challenger and liked it, my 'butt-dyno' said it was worth it. :)


I am planning on adding the following:

RapidBike EVO ECU
Yoshimura RS-4 muffler
K&N air filters


Anything else I should add to the list?

Thanks!

Brian
 

belrix

Well-Known Member
Gold Rider
Nov 2, 2015
381
194
158
49
SouthEast Kansas
I though about a full exhaust but Yoshimura is the only aftermarket muffler that I can find that offers an USFS approved spark arrestor and they aren't offering a header pipe for the AT yet.

I'm interested in the airbox mod, more air equals more power!

Just kicking around the idea
 

Graves

Moderator
Staff member
Legendary Rider
Aug 14, 2016
1,119
349
143
So. Cal.
Black Widow has a head pipe that mates to the OE muffler (https://www.blackwidowexhausts.co.uk/downpipes-de-cat-749-c.asp), so it would stand to reason that the Yosh muffler would attach to the BW header. ???

I though about a full exhaust but Yoshimura is the only aftermarket muffler that I can find that offers an USFS approved spark arrestor and they aren't offering a header pipe for the AT yet.

I'm interested in the airbox mod, more air equals more power!

Just kicking around the idea
 

belrix

Well-Known Member
Gold Rider
Nov 2, 2015
381
194
158
49
SouthEast Kansas
Thanks for the find!

Waiting on this project until later into the Fall, just ordered a new set of tires and tubes!
 

Squily

Well-Known Member
Feb 23, 2016
180
117
133
Esperance Western Australia
Try a full exhaust (exhaust less the cat), K&N's and drill the air filter cover lids, or remove the snorkels and open the holes. I'll bet this will add as much as any re-flashed PCM.
Not the same bike I know, but did the same thing on my old AT. I wasn't happy with the result. I ended up plugging the holes in the airbox again - found there was too much water/moisture coming into the airbox when riding int he rain which would make the bike run crappy. And I noticed no increase in torque and low-down grunt. In fact we experimented on the dyno with various aftermarket exhausts and options (on the RD07) and found best high rpm results were reached with the OEM exhaust. Best lower-end torque with an open system. And the only hp gains between OEM exhaust and various open systems were 2hp (i.e. <5%).

I know every bike is slightly different and may have different results

Rule of thumb we use for carburetor bikes - you can change the filter or the pipe without rejetting, but as soon as you do both, you need to rejet to stop the bike from burning valves and running to lean.

I reckon the AT is already running too lean (for emissions), and any fiddling with the airbox, exhaust etc will exacerbate the issue and possibly nullify any gains. Or potentially cause damage to the topend over the long run. A remapped ECU might give you much more gains than you think (if not in hp, at least in rideabiity and longevity). Biggest problems with ECU remapping - its pretty useless unless you spend the money/time to have it properly adjusted/setup.
 

Graves

Moderator
Staff member
Legendary Rider
Aug 14, 2016
1,119
349
143
So. Cal.
That’s the beauty of FI bikes, if you retain the o2 sensor they adjust themselves.

I know what you mean about drilling air box covers, had a XR650R with a drilled side cover and had to duct tape in the rain, and if a strong enough cross wind the added pressure would blow the engine out like a candle. The best thing I did to that 650 was to port and polish the head, hey there’s the top end rush, had to reject after that one.

Not the same bike I know, but did the same thing on my old AT. I wasn't happy with the result. I ended up plugging the holes in the airbox again - found there was too much water/moisture coming into the airbox when riding int he rain which would make the bike run crappy. And I noticed no increase in torque and low-down grunt. In fact we experimented on the dyno with various aftermarket exhausts and options (on the RD07) and found best high rpm results were reached with the OEM exhaust. Best lower-end torque with an open system. And the only hp gains between OEM exhaust and various open systems were 2hp (i.e. <5%).

I know every bike is slightly different and may have different results

Rule of thumb we use for carburetor bikes - you can change the filter or the pipe without rejetting, but as soon as you do both, you need to rejet to stop the bike from burning valves and running to lean.

I reckon the AT is already running too lean (for emissions), and any fiddling with the airbox, exhaust etc will exacerbate the issue and possibly nullify any gains. Or potentially cause damage to the topend over the long run. A remapped ECU might give you much more gains than you think (if not in hp, at least in rideabiity and longevity). Biggest problems with ECU remapping - its pretty useless unless you spend the money/time to have it properly adjusted/setup.
 
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belrix

Well-Known Member
Gold Rider
Nov 2, 2015
381
194
158
49
SouthEast Kansas
This project has been moved to the back burner, the new helmet, comm system and tires depleted the farkle budget for now.



Sent from my SM-T713 using Tapatalk
 

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